Category 6™

The Unusually Quiet Atlantic Hurricane Season of 2013 Ends

By: JeffMasters, 3:53 PM GMT on November 29, 2013

The end of the unusually quiet Atlantic hurricane season of 2013 is at hand. The final tally of thirteen named storms was above the average of eleven for a season, but the two hurricanes (Ingrid and Humberto) and zero major hurricanes were well below the average from 1950 - 2012 of six and three, respectively. The 2013 season ranked as the sixth-least-active Atlantic hurricane season since 1950, in terms of the collective strength and duration of named storms and hurricanes (ACE index), which was just 33% of the 1981 - 2012 average. The 2013 hurricane season was the first time since 1994 no major hurricanes formed, and was only the third below-normal season since the high-activity period for Atlantic hurricanes began in 1995. NOAA and the U.S. Air Force Reserve flew 45 hurricane hunter aircraft reconnaissance missions over the Atlantic basin this season, totaling 435 hours--the fewest number of flight hours since at least 1966, said NOAA in a press release summarizing the 2013 hurricane season.



Worst storm of the season: Ingrid
Mexico took a severe beating in 2013, with eight landfalling storms: one hurricane (Ingrid) and two tropical storms (Barry and Fernand) from the Atlantic side, and two hurricanes (Manuel and Barbara), and three tropical storms from the Pacific side. The deadliest and most expensive Atlantic storm of 2013 was Hurricane Ingrid, which weakened to a tropical storm with 65 mph winds before hitting Mexico about 200 miles south of the Texas border on September 16, 2013. Ingrid's heavy rains triggered flooding that killed 23 and did $1.5 billion in damage, making the storm the 7th costliest tropical cyclone in Mexican history. Barry and Fernand, which both hit the Mexican coast in the Gulf of Mexico between Tampico and Veracruz, dumped torrential rains and triggered floods that killed five and fourteen people, respectively. The first storm of the season, Tropical Storm Andrea, was the only named storm to make landfall in the United States this year. Andrea brought tornadoes, heavy rain, and minor flooding to portions of Florida, eastern Georgia and eastern South Carolina, causing one fatality and damage less than $25 million. No other deaths were recorded from Atlantic named storms in 2013. Tropical Storm Chantal did minor damage on Dominica and Martinique in the Lesser Antilles, and Tropical Storm Gabrielle did minor damage on Bermuda.


Figure 1. The strongest Atlantic hurricane of 2013, Category 1 Hurricane Ingrid, lays siege to Mexico on September 15, 2013. Ingrid killed 23 and did $1.5 billion in damage to Mexico. On the Pacific side, we see Tropical Storm Manuel, which killed 169 people and did $4.2 billion in damage to Mexico. Image credit: NASA Earth Observatory.

A preseason forecast bust
It was a bad year to be in the seasonal hurricane forecast business. All of the pre-season forecasts called for at least 7 hurricanes, 3 major hurricanes, and an ACE index at least 30% higher than average. With the actual numbers being 2 hurricanes, 0 major hurricanes, and an ACE index of just 33% of average , these forecasts were a major bust. The only pre-season forecast that one could deem successful was issued by a team at Penn State, led by Dr. Michael Mann, who only attempted to predict the number of named storms (they said 12 - 20, with a best estimate of 16.) The preseason forecasts largely failed because many of the factors that usually lead to active seasons that we can look at months beforehand all pointed towards an active season:

1) No El Niño was present. When El Niño conditions are not present in the Eastern Pacific, wind shear tends to be low over the tropical Atlantic, favoring hurricane formation.

2) Ocean temperatures were above average.

3) Sea level pressures were lower than average.

4) Wind shear was near average.

5) The African Monsoon was active, with many strong tropical waves emerging from the coast of Africa. These disturbances form the nucleus for about 85% of all major hurricanes.

However, these factors tell only roughly 50% of the story. The other 50% is not predictable more than a week or two in advance: the large-scale atmospheric circulation. This summer and fall, an unusually strong trough of low pressure over the Central Atlantic brought large amounts of dry, sinking air to the tropical Atlantic. Large amounts of dry air also invaded from the Sahara, and from Northeast Brazil, which had suffered the most expensive drought in Brazil's history ($8 billion) earlier in the year. The combined onslaught of dry air from these multiple sources was enough to overwhelm the otherwise favorable conditions for development, leading to one of the quietest Atlantic hurricane seasons on record. According to Phil Klotzbach of the Colorado State seasonal forecast team, the relative humidity at the 700 mb level (roughly 10,000 feet) in the Main Development Region of the tropical Atlantic (7.5- 22.5°N, 20-75°W) in August was the lowest observed in the past 35 years, and was the 8th lowest during September. The strength of the sinking motion of the air in this region during August and September was the second greatest of the past 35 years. It's tough to sustain a thunderstorm updraft when there is so much dry, sinking air at middle levels of the atmosphere.



Special Characteristics of the 2013 Hurricane Season
The 2013 hurricane season had the following special characteristics, as summarized by Phil Klotzbach of the Colorado State seasonal forecast team:

• Thirteen named storms occurred during 2013. This is the most named storms to occur in a year with two or fewer hurricanes in the historical record. The 1931 hurricane season had thirteen named storms but only three hurricanes.

• 35.75 named storm days (NSD) occurred during 2013. This is the fewest NSD since 2009 (30 NSD).

• Two hurricanes formed in 2013. This is the fewest hurricanes since 1982, when two hurricanes also formed.

• No major hurricanes formed in 2013. The last year with no major hurricane formations was 1994.

• ACE in 2013 was only 30 units. This is the lowest ACE for an Atlantic hurricane season since 1983 (17 ACE units.)

• No major hurricanes made U.S. landfall in 2013. The last major hurricane to make U.S. landfall was Wilma (2005), so the U.S. has now gone eight years without a major hurricane landfall. Since 1878 when relatively reliable landfall data became available, the U.S. has never had an eight-year period without a major hurricane landfall.

• The maximum intensity reached by any hurricane this year was 85 mph (Humberto and Ingrid). This is the weakest maximum intensity achieved by the most intense hurricane of a season since 1968 (Gladys, 85 mph.)

• Humberto reached hurricane strength early on September 11. It became the second latest forming first hurricane of the year, developing into a hurricane just hours before the previous record latest forming first hurricane of the year (Gustav, 2002.)

• Two tropical cyclones (TCs) formed in the Main Development Region (south of 23.5°N, east of 75°W) prior to 1 August. The last year with two TCs forming in this region prior to 1 August was all-time busiest hurricane season on record, 2005. The median ACE of the 10 years with two TCs in the MDR prior to 1 August was 174 ACE units. The 2013 season clearly defied many of the typical pre-season climate signals.


Video 1. Wunderground member CycloneOz put together this animation of all the named storms of the 2013 Atlantic hurricane season.

Have a great weekend, everyone, and I'll be back Monday with a new post.

Jeff Masters

Hurricane

Major Winter Storm Delaying Travel in Eastern U.S.; Lehar Weakens to a Tropical Storm

By: JeffMasters, 3:04 PM GMT on November 27, 2013

The busiest travel day of the year in the U.S. is at hand this Wednesday, and Winter Storm Boreas continues to slow travel over much of the Eastern U.S. with a nasty mix of snow, sleet, freezing rain, heavy rain, and high winds. Dangerous snowy and icy travel will continue to cause trouble in many of the high elevation areas from the Smoky Mountains to Maine Wednesday. The greatest snows of 6+ inches will fall in the Adirondack Mountains of New York, and strong northwest winds will bring lake effects of 2 - 4" to Rochester, NY and much of the south shore of Lake Ontario.


Figure 1. Winter Storm Boreas heads up the Eastern U.S. on Tuesday, November 26, 2013. Image credit: NASA Earth Observatory.

A very wet and windy storm for the U.S.
Boreas has tapped into an "Atmospheric River" of very moist air from the Gulf of Mexico, and the amount of water vapor available to make rain (the "Precipitable Water") was near record highs (for November) along the East Coast Tuesday night and Wednesday morning. The high elevation areas of South Carolina, North Carolina, and Virginia received more than 3" of rain in a 24-hour period ending at 8 am EST Wednesday, and both New York City and Philadelphia got more than 2". The heavy rains, combined with cloud ceilings as low as 500 feet and wind gusts as high as 40 mph, have slowed air traffic landing at New York's La Guardia airport and in Philadelphia. The FAA web site warned of 1 hour delays for flights arriving in Philadelphia, and 2 hours at La Guardia, on Wednesday morning. However, none of the other 38 major airports in the U.S. was reporting delays in excess of over 15 minutes Wednesday morning, and Winter Storm Boreas has been more of a nuisance than a travel disaster.

Accompanying Boreas' heavy rains along the coast have been high winds; a Wind Advisory for sustained winds of 20 - 30 mph, with gusts up to 60 mph, is in place along much of the coast from New Jersey to Maine. While the rains will be gone on Thursday in time for the Macy's Thanksgiving Day Parade in New York City, winds will still be strong, making conditions potentially too dangerous for the balloons used in the parade. These balloons are not allowed to fly if the city experiences sustained winds of 23 mph with gusts of 34 mph. The forecast calls for sustained winds of 15 - 25 mph gusting to 40 mph on Thursday.


Figure 2. Observed precipitation for the 24-hour period ending Wednesday, November 27, 2013. Image credit: NOAA.

Lehar weakens to a tropical storm; threat to India lessens
Cyclone Lehar has met up with dry air and strong upper level winds that have torn into the storm, reducing it to a tropical storm with 65 mph winds at it heads west-northwest at 17 mph towards India's Bay of Bengal coast. Satellite images show that Lehar is much less organized than before, with a much diminished area of heavy thunderstorms. Cooler waters near shore and continued dry air and wind shear as the storm nears landfall will keep Lehar below hurricane strength until landfall. Landfall is expected to occur between 06 - 12 UTC Thursday, November 28, in the Andhra Pradesh state of India.

Have a great Thanksgiving, everyone, and I'll be back Friday with a new post.

Jeff Masters

Winter Weather Hurricane

Snow, Freezing Rain, Heavy Rain, and High Winds Hit Eastern U.S.; India Watches Lehar

By: JeffMasters, 3:31 PM GMT on November 26, 2013

The weather gods are interfering mightily with the busiest travel period of the year in the U.S., as powerful Winter Storm Boreas plows up the Eastern seaboard, bringing a nasty mix of snow, sleet, freezing rain, heavy rain, high winds, and severe thunderstorms. Woe to ye who attempt to traverse the Pennsylvania Turnpike through Western Pennsylvania; my award for worst weather of the day goes to Somerset, PA. Tuesday's forecast calls for freezing rain of up to 1/10" ice accumulation, accompanied by 1 - 3" of snow, followed by rain and freeing rain Tuesday night, followed by another 2 - 4" of snow on Wednesday. Dangerous snowy and icy travel will dominate all the high elevation areas from the Smoky Mountains to Maine. The worst freezing rain will be in the mountains of Western North Carolina, where up to 1/4" of ice accumulation is expected. The greatest snows of 6+ inches will fall in Western New York and Northwest Pennsylvania. Rochester, NY is expected to get up to a foot of snow, due to strong northwest winds off of Lake Ontario that will add a extra lake effect boost. Six plus inches of snow are also a good bet in Pittsburgh and Buffalo.


Figure 1. Crews spray deicing solution onto an American Airlines 737 before departure at Dallas-Fort Worth International airport, Nov. 25, 2013. (AP Photo/Brandon Wade)

A very wet and windy storm for the coast
Boreas has tapped into an "Atmospheric River" of very moist air from the Gulf of Mexico, and the amount of water vapor available to make rain (the "Precipitable Water") will be near record highs (for November) along the East Coast. For example, in New York City, the Precipitable Water is expected to be near 1.7" on Wednesday morning; there has been only one higher value of Precipitable Water recorded there in November since 1948 (2.02" on November 11, 2003.) All this moisture will generate heavy rains for coastal New England and the Mid-Atlantic, with rain amounts of 3 - 4" commonplace. The low clouds and strong winds accompanying these rains will slow air travel throughout the Mid-Atlantic and Northeast. Fortunately, river levels are low due to moderate drought in much of the Northeast, and only minor flooding is expected from the heavy rains.

Accompanying the heavy rains along the coast will be high winds; a Wind Advisory for sustained winds of 20 - 30 mph, with gusts up to 50 mph, is in place along much of the coast from Delaware to Maine. While the rains will be gone on Thursday in time for the Macy's Thanksgiving Day Parade in New York City, winds will still be strong, making conditions potentially too dangerous for the balloons used in the parade. These balloons are not allowed to fly if the city experiences sustained winds of 23 mph with gusts of 34 mph. The forecast calls for sustained winds of 15 - 20 mph gusting to 40 mph on Thursday.


Figure 2. Predicted precipitation for the 3-day period ending Friday, November 29, 2013. This week's storm is expected to dump heavy rains of 3 - 4 inches along a long swath from North Carolina to Maine. Image credit: NOAA.

Category 1 Cyclone Lehar headed towards India
Dangerous Category 1 Cyclone Lehar is slowly intensifying as it heads west-northwest at 10 mph towards India's Bay of Bengal coast. Satellite images show that Lehar--which is the Hindustani word for "wave"--continues to have a large Central Dense Overcast (CDO) of high cirrus clouds over its center, which is characteristic of intensifying tropical cyclones near Category 1 hurricane strength. Lehar has not been able to form a prominent eye, and is likely having problems getting organized in the face of moderate wind shear of 10 - 20 knots. Ocean temperatures are a very warm 28 - 29°C, and Lehar should be able to attain Category 2 strength before landfall. Cooler waters near shore and an increase in wind shear as the storm nears landfall will likely mean that Lehar will be weakening as it comes ashore. Landfall is expected to occur near 06 UTC Thursday, November 28, in the Andhra Pradesh state of India. This is the same portion of the coast that Cyclone Helen hit on Friday as a tropical storm with 40 mph winds. Helen's heavy rains killed eleven people, caused widespread severe agricultural damage, and left the soils saturated, which will make the rains from Lehar doubly dangerous. Also of concern is the storm surge, which will impact a portion of the coast that is heavily populated and low-lying. The India Meteorological Agency (IMD) is predicting a storm surge of up to 2 - 3 meters (7 - 10 feet) to the right of where the eye makes landfall.


Figure 3. Cyclone Lehar over the Bay of Bengal at approximately 04:30 UTC November 26, 2013. At the time, Lehar was at Category 1 strength with top winds of 85 mph. Image credit: NASA.

An unusually active tropical cyclone season for India
In addition to Cyclone Helen, India's Bay of Bengal coast also was hit this year by Tropical Cyclone Phailin, a Category 4 storm with 140 mph winds, which killed 44 people and did $1.1 billion in damage on October 12, 2013. It's unusual for India to get hit by so many named storms in one year; the last time three or more named storms did so was in 1996, when six storms of at least tropical storm intensity hit. Only four Bay of Bengal tropical cyclones have hit India at hurricane strength since 2000, if we include Cyclone Phailin from 2013. The others were:

Category 1 Cyclone Aila of May 25, 2009, which hit near Kolkata, killing 96, causing $553 million in damage.
Category 1 Cyclone Thane, of December 30, 2011, which hit Southeast India, killing 48, causing $376 million in damage.
Category 1 Cyclone 05B, which hit Southern India on November 29, 2000, killing six.

The last major tropical cyclone to hit the portion of the coast that Lehar is threatening occurred on June 14 1996, when Category 4 Tropical Cyclone 07B struck, killing 731 people. Wunderground's weather historian Christopher C. Burt has a detailed post on India's tropical cyclone history. During the past two centuries, 42 percent of Earth's tropical cyclone-associated deaths have occurred in Bangladesh, and 27 percent have occurred in India (Nicholls, R.J.N., N. Mimura, J.C. Topping, 1995, "Climate change in south and south-east Asia: some implications for coastal areas," J Glob Environ Eng 1995;1:137–54.)

Jeff Masters

Winter Weather Hurricane

Dangerous Category 1 Lehar Headed for India; Wet Winter Storm for U.S. East Coast

By: JeffMasters, 3:52 PM GMT on November 25, 2013

Dangerous Category 1 Cyclone Lehar is intensifying as it heads west-northwest at 8 mph towards India's Bay of Bengal coast. Satellite images show that Lehar--which is the Hindustani word for "wave"--has developed a large Central Dense Overcast (CDO) of high cirrus clouds over its center, which is characteristic of intensifying tropical cyclones approaching hurricane strength. With wind shear a moderate 10 - 20 knots and ocean temperatures a very warm 28 - 29°C, Lehar is expected to continue to intensify to a major Category 3 storm until just before landfall, which is expected to occur near 03 UTC Thursday, November 28 in the Andhra Pradesh state of India. This is the same portion of the coast that Cyclone Helen hit on Friday as a tropical storm with 40 mph winds. Helen's heavy rains killed eleven people, caused widespread severe agricultural damage, and left the soils saturated, which will make the rains from Lehar doubly dangerous. Also of concern is the storm surge, which will impact a portion of the coast that is heavily populated and low-lying. The India Meteorological Agency (IMD) is predicting that Lehar will generate a storm surge of up to 1.6 - 2.9 meters (5.2 - 9.5 feet) to the right of where the eye makes landfall.


Figure 1. Cyclone Lehar over the Andaman Islands in the Bay of Bengal at 04:25 UTC November 25, 2013. At the time, Lehar was at Category 1 strength with top winds of 75 mph. Image credit: NASA.

An unusually active tropical cyclone season for India
In addition to Cyclone Helen, India's Bay of Bengal coast also was hit this year by Tropical Cyclone Phailin, a Category 4 storm with 140 mph winds, which killed 44 people and did $1.1 billion in damage on October 12, 2013. It's unusual for India to get hit by so many named storms in one year; the last time three or more named storms did so was in 1996, when six storms of at least tropical storm intensity hit. Only four Bay of Bengal tropical cyclones have hit India at hurricane strength since 2000, if we include Cyclone Phailin from 2013. The others were:

Category 1 Cyclone Aila of May 25, 2009, which hit near Kolkata, killing 96, causing $553 million in damage.
Category 1 Cyclone Thane, of December 30, 2011, which hit Southeast India, killing 48, causing $376 million in damage.
Category 1 Cyclone 05B, which hit Southern India on November 29, 2000, killing six.

The last major tropical cyclone to hit the portion of the coast that Lehar is threatening occurred on June 14 1996, when Category 4 Tropical Cyclone 07B struck, killing 731 people. Wunderground's weather historian Christopher C. Burt has a detailed post on India's tropical cyclone history. During the past two centuries, 42 percent of Earth's tropical cyclone-associated deaths have occurred in Bangladesh, and 27 percent have occurred in India (Nicholls, R.J.N., N. Mimura, J.C. Topping, 1995, "Climate change in south and south-east Asia: some implications for coastal areas," J Glob Environ Eng 1995;1:137–54.)


Figure 2. Predicted precipitation for the 7-day period ending Monday, December 2, 2013. This week's storm is expected to dump heavy rains of 2+ inches along a long swath of the U.S., from Louisiana to Maine. Image credit: NOAA.

Winter Storm Boreas a heavy rain event for the coast
A powerful and very wet winter storm will slog across the Southeast U.S. Monday and Tuesday and up the Mid-Atlantic coast on Wednesday. The models have come into fair agreement that the storm, dubbed "Boreas", will be a heavy rain event for coastal New England and the Mid-Atlantic, with snow falling inland at higher elevations. The greatest snows of 6+ inches will likely fall on Tuesday through Wednesday in Southwest New York and Northwest Pennsylvania. Pittsburgh and Buffalo are under Winter Storm Watches, and could see 3 - 5" of snow, snarling travel on the busiest travel day of the year.

Jeff Masters

Hurricane

October 2013: Earth's 7th Warmest October; Thanksgiving Eve Nor'easter Coming

By: JeffMasters, 4:04 PM GMT on November 22, 2013

October 2013 was the globe's 7th warmest October since records began in 1880, according to NOAA's National Climatic Data Center (NCDC). NASA rated it the 8th warmest October on record. The year-to-date period of January - October has been the 7th warmest such period on record. October 2013 global land temperatures were the 8th warmest on record, and global ocean temperatures were also the 8th warmest on record. October 2013 was the 344th consecutive month with global temperatures warmer than the 20th century average. Global satellite-measured temperatures in October 2013 for the lowest 8 km of the atmosphere were 11th or 6th warmest in the 35-year record, according to Remote Sensing Systems and the University of Alabama Huntsville (UAH), respectively. Northern Hemisphere October snow cover was the 7th greatest in the 46-year record. Wunderground's weather historian, Christopher C. Burt, has a comprehensive post on the notable weather events of October 2013 in his October 2013 Global Weather Extremes Summary.


Figure 1. Departure of temperature from average for October 2013, the 7th warmest October for the globe since record keeping began in 1880. Record October warmth was observed across parts of Alaska, northwestern Canada, northwestern Africa, and southern Australia. The western U.S., Turkey, and northeastern Siberia were cooler than average. Image credit: National Climatic Data Center (NCDC) .

The three billion-dollar weather disasters of October 2013
Three billion-dollar weather-related disasters hit the Earth during October 2013, bringing the world-wide tally of these disasters through October 2013 to 35, according to the October 2013 Catastrophe Report from insurance broker Aon Benfield. If we add November's Super Typhoon Haiyan, the total reaches 36. This is the second highest yearly total of billion-dollar weather disasters for the globe since accurate disaster records began in 2000, though the total cost of weather-related disasters so far in 2013 is below the average for the past ten years, according to Senior Scientist Steve Bowen of Aon Benfield. The record highest number of billion-dollar weather disasters was 40, set in 2010. For comparison, during all of 2012, there were 27 billion-dollar weather disasters; the tally in 2011 was 35 (adjusted for inflation.) The U.S. total through October 2013 is seven.




Disaster 1. Category 2 Typhoon Fitow hit the southern Japanese Islands on October 4, killing two people. Fitow weakened to a tropical storm and made landfall in China just north of Taiwan on October 7, dumping torrential rains that caused $6.7 billion in damage and killed six. In this MODIS image from 02:15 UTC October 5, 2013, Category 2 Typhoon Fitow is approaching China. Image credit: NASA.


Disaster 2. Tropical Cyclone Phailin hit the northeast coast of India on October 12, 2013 as a weakening Category 4 storm with 140 mph winds. Due to strong preparedness efforts by India, the storm killed only 44 people, in a location where 10,000 people had been killed by a similar-strength cyclone in 1999. Damage from Phailin was estimated at $1.1 billion, which would make it the 6th most expensive tropical cyclone in India's history (adjusted for inflation.) In this image taken at approximately 04:30 UTC on October 11, 2013, Phailin fills the Bay of Bengal as a top-end Category 4 storm with winds of 155 mph. Image credit: NASA.


Disaster 3. Extratropical storm "Christian" hit the United Kingdom, France, Belgium, the Netherlands, and Scandinavia on October 28, killing 18 and causing at least $2 billion in damage. A new all-time wind speed record in Denmark of 192.6 kph (120 mph) was measured that day at Kegnæs on the Baltic Sea, close to the German border. In this image, large waves break against the dyke at the entrance of the port of Boulogne, northern France, on October 28, 2013. Image credit: PHILIPPE HUGUEN/AFP/Getty Images)

Neutral El Niño conditions continue in the equatorial Pacific
For the 19th month in row, October 2013 featured neutral El Niño conditions in the equatorial Eastern Pacific. NOAA's Climate Prediction Center (CPC) expects neutral El Niño conditions to last into the Northern Hemisphere spring of 2014, as do the large majority of the El Niño models. Temperatures in the equatorial Eastern Pacific need to be 0.5°C below average or cooler for three consecutive months for a La Niña episode to be declared; sea surface temperatures were 0.0°C from average as of November 18, and have been +0.1 to -0.4°C from average since April 1, 2013.

Arctic sea ice falls to 6th lowest October extent on record
Arctic sea ice extent during October was 6th lowest in the 35-year satellite record, and had the largest October extent since 2008, according to the National Snow and Ice Data Center (NSIDC).

Winter Storm Boreas likely to become season's first Nor'easter on Thanksgiving Eve
A potent winter storm (Boreas) is bringing snow and difficult travel conditions to Arizona, and will spread a variety of dangerous winter weather across Texas, New Mexico, Oklahoma, Kansas, Colorado, and Utah over the weekend. On Monday and Tuesday, the storm will dump heavy rains over the Southeast U.S., before emerging over the coastal waters of the Mid-Atlantic on Wednesday morning. The models are in fair agreement that Boreas will then intensify into the season's first significant Nor'easter on Wednesday afternoon, bringing heavy rain to coastal New England and the Mid-Atlantic, snow farther inland at higher elevations, and minor coastal flooding due to strong winds. The potential for 6+ inches of snow in Upstate New York and the northern portions of New Hampshire, Vermont, and Maine looks good, and there is the possibility that Washington D.C. and Philadelphia could get 2 - 4" of snow Wednesday afternoon and evening, after a period of heavy rain. With the storm still five days away, confidence in the timing of the storm and the potential location and amount of snow is low, and we will have to see how the models evolve in their handling of this potential Thanksgiving Eve Nor'easter.


Figure 2. "Tipping Points" host Bernice Notenboom in Nepal.

"India Water Crisis" and "Stonados" air Saturday at 9 pm EDT
“Tipping Points”, the landmark 6-part climate change TV series that began airing in October on The Weather Channel, airs for the final time on Saturday night, November 23, at 9 pm EDT. The new episode, "India Water Crisis", goes to the top of the world--the Himalayas--and all the way down across the plains of India, following one of the most famous river systems in the world--the Ganges. Fresh water sources from the Himalayas that provide water to over one billion people are under threat, but just what is happening here--and if the region is approaching a tipping point--are what polar explorer and climate journalist Bernice Notenboom seeks to find out.

For those of you more into watching a show about a preposterous imaginary weather threat instead of a worrisome real one, SyFy Channel's "Stonados" is airing at the same time as "Tipping Points." That's right--a killer tornado hurls giant stones that "explode like bombs" in Boston. "Stonados" was originally set to air before the equally ridiculous "Sharknado" movie. However, the Boston Marathon bombings occurred the week before, and the producers wisely pulled "Stonado" in favor of "Sharknado." One can imagine all sorts of possible sequels--Lobsterbado! Spidernado! Snakenado! After watching the "Stonado" trailer, my wife asked me, "why are the rocks exploding? What's the science behind that?" I told her that you don't have to have any science in a movie made by Asylum studios, you just make things explode.

Have a great weekend everyone!

Jeff Masters

Climate Summaries Boreas

NOAA's Winter Forecast: Drought and Warmth in the South

By: JeffMasters, 4:49 PM GMT on November 21, 2013

Expect increased chances of a warmer than average winter across much of the Southern U.S. and New England, and a cooler than average winter across portions of the Northern Plains near the Canadian border, said NOAA in their annual Winter Outlook, released on November 21. The forecast also calls for drought to persist and intensify over much of the Southwest U.S., and to develop over the Southeast U.S. This year's forecast was more difficult than usual to make, said Mike Halpert, deputy director of NOAA’s Climate Prediction Center, due to the lack of an El Niño or La Niña event. When these patterns of above average or below average ocean temperatures in the Eastern Pacific are present, they strongly impact winter weather patterns by altering the path of the jet stream and the associated winter storms that travel along the axis of the jet stream. We currently have neutral El Niño conditions over the tropical Pacific Ocean, which means that ocean temperatures are near average along the Equator from the coast of South America to the Date Line, putting more subtle, harder-to-predict factors in control of this year's winter weather. NOAA relied heavily on climate trends over the past fifteen years and long-range computer models such as their CFS forecast model to predict this year's winter weather.


Figure 1. Forecast temperature and precipitation for the U.S. for the upcoming winter, as predicted in the NOAA Winter Outlook, released on November 21, 2013.


Figure 2. NOAA's seasonal drought outlook, issued on November 21, 2013, calls for drought to persist and intensify over much of the Southwest U.S. this winter, and to develop over the Southeast U.S.

What will the Arctic Oscillation and North Atlantic Oscillation do?
While El Niño is usually a key factor controlling winter weather patterns, it is often overshadowed by the North Atlantic Oscillation (NAO)--a climate pattern in the North Atlantic Ocean of fluctuations in the difference of sea-level pressure between the Icelandic Low and the Azores High. The NAO controls the strength and direction of westerly winds and storm tracks across the North Atlantic. A large difference in the pressure between Iceland and the Azores (positive NAO) leads to increased westerly winds and mild and wet winters in Europe. Positive NAO conditions also cause the Icelandic Low to draw a stronger south-westerly flow of air over eastern North America, preventing Arctic air from plunging southward. In contrast, if the difference in sea-level pressure between Iceland and the Azores is small (negative NAO), westerly winds are suppressed, allowing Arctic air to spill southwards into eastern North America and Europe more readily. This pattern is kind of like leaving the refrigerator door ajar--the Arctic refrigerator warms up, but all the cold air spills out into the house where people live. The NAO is a close cousin of the Arctic Oscillation (AO), and can be thought of as the North Atlantic component of the larger-scale Arctic Oscillation. Since the AO is a larger-scale pattern, scientists refer to the AO instead of the NAO when discussing large-scale winter circulation patterns. The winter of 2009 - 2010 had the most extremely negative NAO pattern (and AO pattern) since record keeping began in 1950. Vicious "Snowmageddon" winter storms occurred in both the U.K. and the United States that winter, as both Europe and North America suffered though an unusually cold and snowy winter. Thus, the phase and strength of the AO/NAO pattern is a key factor controlling winter weather. Unfortunately, this pattern is not predictable more than about two weeks in advance, and thus was not considered by NOAA in their forecast for the upcoming winter.

In my April 2, 2012 blog post, Arctic sea ice loss tied to unusual jet stream patterns, I discuss research that argues that Arctic sea ice loss may cause an increase in the probability of cold, negative-AO winters in the U.S. and Northern Europe. The warm phase of the decades-long pattern of warming and cooling of Atlantic Ocean waters known as the Atlantic Multidecadal Oscillation (AMO), which we've been stuck in since 1995, may also increase the odds of negative-AO winters. Both of these factors may act to increase the odds of a cold winter this year. Climate change wunderblogger Ricky Rood notes in the just-posted final installment of his 7-part series on Climate Change and the Arctic Ocsillation that the AO has shown an increasing trend since 1960 towards getting stuck in the same phase for multiple years in row. Since last year was dominated by negative AO conditions, we might expect increased chances of another predominantly negative-AO winter this year, with increased odds of colder than average conditions in the Eastern U.S. and Northern Europe. Note, though, that last winter was a bit of an oddball. The AO was predominately negative, and we saw cold and snowy weather in Northern Europe, as expected. However, the AO and NAO were out of phase, which only happens about 10% of the time, and the U.S. had a much warmer than average winter (19th warmest on record.)


Figure 3. Last year's NOAA forecast for the winter of 2012 - 2013 (top two panels), made in October 2012, called for increased chances of warm weather over the Western U.S. and cool weather over Florida. The contiguous U.S. ended up having its 19th warmest winter in the 118-year record. Florida recorded a top-ten warmest winter, and most of the Western U.S. ended up near average or cooler than average (bottom left panel.) Last year's winter precipitation forecast fared well for the Southeast U.S., which had a top-ten wettest winter on record (see bottom right panel for what actually happened.) The predicted dry winter for the Pacific Northwest also materialized. However, the Upper Midwest was unusually wet, in contradiction to predictions for above-average chances of a dry winter.

Winter weather and the sunspot cycle
Another major influence on the AO and winter circulation patterns may be the 11-year solar cycle. Recent satellite measurements of ultraviolet light changes due to the 11-year sunspot cycle show that these variations are larger than previously thought, and may have major impacts on winter circulation patterns. A climate model study published in Nature Geosciences by Ineson et al. (2011) concluded that during the minimum of the 11-year sunspot cycle, the sharp drop in UV light can drive a strongly negative AO pattern, resulting in "cold winters in northern Europe and the United States, and mild winters over southern Europe and Canada, with little direct change in globally averaged temperature." The winters of 2009 - 2010 and 2010 - 2011 both occurred during a minimum in the 11-year sunspot cycle and fit this pattern, with strongly negative AO conditions leading to cold and snowy weather in the Eastern U.S. (15th coldest and 37th coldest winters in U.S. history, respectively.) There was more solar activity during the winters of 2011 - 2012 and 2012 - 2013, which had more positive AO conditions than the previous two winters. The coming winter of 2013 - 2014 will have about the same level of solar activity as last winter (Figure 3).


Figure 4. The number of sunspots from 2000 - 2013 shows that solar minimum occurred during the winter of 2008 - 2009, and that solar activity is now near a peak. Image credit: NOAA Space Weather Prediction Center.

Summary: flip a coin or catch a woolly worm
I'm often asked by friends and neighbors what my forecast for the coming winter is, but I tell them to flip a coin, or catch some woolly bear caterpillars for me so I can count their stripes and make a woolly bear winter forecast. I never make seasonal winter forecasts for the same reason I never make seasonal hurricane forecasts--why make a forecast that will be wrong nearly half of the time? Seasonal forecasts have some skill, and you'll come out ahead if you bet on their accuracy year after year. But forecast busts are common, and you'll often be remembered for your most recent terrible seasonal forecast. Making an accurate winter forecast is very difficult, as the interplay between El Niño, the AO/NAO, the AMO, Arctic sea ice loss, and the 11-year sunspot cycle is complex and poorly understood. I've learned to expect the unexpected and unprecedented from our weather over the past few winters; perhaps the most unexpected thing would be a very average winter during 2013 - 2014. Note that this year's Woolley Worm Festival held in October in Banner Elk, North Carolina crowned as champion a woolley bear caterpillar named "Fuzz" with no black bands on it. Local folklore has it that the woolly worm’s 13 body segments, which are brown or black in color, represent the 13 weeks of winter. More black segments mean a harsher winter; a majority of brown segments represent a milder winter. Fuzz's lack of black bands implies an unusually warm winter for U.S. East Coast, and this winter's official woolly worm forecast, beginning December 21, looks like this:

Week 1: Average Cold Wet Snow and Rain
Week 2: Average Cold Wet Snow and Rain
Week 3: Average Cold Wet Snow and Rain
Week 4: Above Average Temperatures
Week 5: Above Average Temperatures
Week 6: Above Average Temperatures
Week 7: Above Average Temperatures
Week 8: Above Average Temperatures
Week 9: Warm Weather
Week 10: Warm Weather
Week 11: Warm Weather
Week 12: Warm Weather
Week 13: Warm Weather

Jeff Masters

Winter Weather

Floods From Mediterranean Storm 'Ruven' Kill 18 in Sardinia, Italy

By: JeffMasters, 3:56 PM GMT on November 20, 2013

Slow-moving and powerful Extratropical Storm Cleopatra (called Ruven by the Free University of Berlin) dumped prodigious rains over the Mediterranean island of Sardinia on Monday, triggering floods that have killed at least eighteen people. According to weather records researcher Maximiliano Herrera, the highest 24-hour rainfall recorded at an official station was 467 mm (18.39") measured at Orgosolo (Nuoro province.) Note that media reports on Tuesday incorrectly reported the deluge as occurring in less than two hours. Monday's deluge was at most the 3rd greatest 24-hour rainfall event for Sardinia. An October 16, 1951 storm brought 544 mm (21.42") in 24 hours to Sicca d' Erba, causing the greatest 20th Century flood in Sardinia history. Second place goes to Villagrande Strisaili on December 6, 2004, when 517mm (20.35") fell.


Figure 1. Extratropical Storm Cleopatra/Ruven over the Mediterranean at night, taken at approximately 6 UTC (1:30 am EST) November 19, 2013. Image credit: Navy Research Lab, Monterrey.

Slow moving hybrid storm to blame
Monday's extreme rainfall event was caused by a slow-moving extratropical low pressure system that lingered over relatively warm 19 - 20°C waters Mediterranean waters long enough to develop a shallow warm core, according to cyclone phase space diagrams from the GFS and UKMET models available from Florida State University, and an analysis from the European Storm Forecast Experiment. As the low deepened to a central pressure near 990 mb, bands of heavy thunderstorms developed over the mountainous terrain of Sardinia and dumped torrential rains. Ocean temperatures were about 0.5°C (1°F) above average, which helped intensify the storm's rains. While the storm's shallow warm core meant that Cleopatra/Ruven had a hybrid nature and was able to pull heat energy out of the ocean like a hurricane does, this was not the primary cause of the heavy rain, which would have occurred without the storm having a shallow warm core. Hybrid storms that bring extreme weather to the Mediterranean happen regularly; I blogged in November 2011 about a hybrid storm (Rolf) that brought heavy rains and 95 mph wind gusts to Southern France.

The jet stream set-up for this extreme event was very much like the ones that spawned this year's destructive floods in Calgary, Canada, Boulder, Colorado, and Central Europe--a slow-moving upper low trapped to the south of a blocking ridge of high pressure. A NOAA chart showing the amount of "blocking"--where on the planet ridges of high pressure are getting "stuck"--shows pronounced blocking near 0°E (over the UK). The plot also shows a major block over Alaska, which has brought some remarkable warmth there (see Chris Burt's post on this, More Crazy Weather in Alaska). Slow-moving lows stay in place longer, allowing greater rains to fall over a localized area, increasing the risk of catastrophic flooding. A big question is how climate change may affect the incidence of blocking. The latest 2013 IPCC report has this to say about the subject: "Increased ability in simulating blocking in models and higher agreement on projections indicate that there is medium confidence that the frequency of Northern and Southern Hemisphere blocking will not increase, while trends in blocking intensity and persistence remain uncertain." It seems like we've been getting more than our fair share of these slow-moving "blocked" storms that generate extreme rainfall events, though; I discussed the possibility that climate change may be at work in this regard in a post on the $22 billion flood that hit Central Europe this summer.


Video 1. The BBC report, "Cyclone Cleopatra traumatises people of Sardinia." Thanks go to wunderground member barbamz for posting this link in my blog comments.

Jeff Masters

Extreme Weather Flood

Midwest Cleans up 2013's Biggest Severe Weather Outbreak; Floods Kill 17 in Sardinia

By: JeffMasters, 3:59 PM GMT on November 19, 2013

Damage surveys continue in the Midwest U.S. after a stunning and violent late-season severe weather outbreak swept through on Sunday, killing at least eight people and leaving widespread significant damage. Two violent EF-4 tornadoes and one strong EF-3 tornado hit Illinois, killing six, making Sunday Illinois' deadliest November day for tornadoes in its history. The most widespread damage from Sunday's outbreak occurred in the town of Washington (population 16,000), about 140 miles southwest of Chicago, where a violent EF-4 tornado destroyed or heavily damaged 250 - 500 homes and an apartment complex. NOAA's Storm Prediction Center logged 85 preliminary tornado reports from Sunday, along with 455 reports of high wind gusts and 32 reports of hail. Seventeen of the wind gusts were in excess of 74 mph (hurricane strength.) The grand total of 572 severe weather reports (filtered to remove duplicates) for the day were the most of any day of 2013, surpassing the 538 total reports from June 13. The 85 preliminary tornado reports is also the highest for any day of 2013, surpassing the 62 reports from January 29.


Figure 1. An aerial view of Washington, Illinois on Sunday, Nov. 17, 2013, after a tornado tore through the area. (Photo by Tasos Katopodis/Getty Images)


Video 1. View from a tugboat on the Ohio River of the EF-3 tornado that hit Brookport, Illinois, killing three people. It is difficult to see as it was shot through the windshield of the tugboat, but you can see evidence of the circulation in the distance. The most impressive part of the video is watching the rain finally reach the boat at around 3:00, as a rain-wrapped circulation crosses the river in front, heading towards the town of Brookport. Looking at the orientation of the town along the river, these guys were looking directly into the circulation, and the rain curtains overtaking their boat is likely the Rear Flank Downdraft (RFD) moving over them.  Thanks go to TWC's Sarah Dillingham for the link and the commentary.

Sunday's November tornado outbreak: how rare?
Sunday's outbreak will probably rank as the second to fourth most prolific November tornado outbreak since 1950. But what was really remarkable about the outbreak was how far north it extended. With three confirmed tornadoes on Sunday, Michigan has increased its total number November tornadoes observed since 1950 by 50%, from six to nine. Prior to Sunday, Indiana had recorded 57 November tornadoes. That total increased by 26 on Sunday, which was the 3rd busiest day for tornadoes in Indiana history (the record: 37 tornadoes on June 2, 1990.) Seven confirmed tornadoes occurred in the 23-county region of Northeast Illinois and Northwest Indiana serviced by the Chicago NWS. Prior to Sunday’s tornado outbreak, there had been just twelve November tornadoes in this region since accurate tornado records began in 1950. The 101 tornado warnings issued in Illinois on Sunday represented 52% of all November tornado warnings issued in the state since 1986. The two EF-4 tornadoes that struck Illinois were the 2nd and 4th most northerly EF-4s ever recorded in the U.S. during the month of November, according to data from the Tornado History Project. Prior to Sunday, only twenty EF-4s had occurred in the U.S. in November dating back to 1950. Also notable is the fact that the intensity and areal extent of this severe weather outbreak resulted in widespread damage over a huge area, making it possible that this will be the first November severe weather outbreak in history to exceed $1 billion in damages. November severe weather outbreaks are rare enough and our database poor enough that we cannot make any definitive statements on how climate change may be affecting them, but one would expect to see cold-season severe weather events become increasingly common farther to the north in a warming climate.

Here is a list of the largest November tornado outbreaks since 1950:

95 tornadoes: November 21–23, 1992, Texas to Mississippi and into the Ohio Valley. The most intense and largest November outbreak on record in U.S. history. Produced violent tornadoes from Texas to Mississippi and into the Ohio Valley, including six F4s and two extremely long-track tornadoes, 160 miles and 128 miles.
75 tornadoes: November 9–11, 2002, Southeast U.S. and Ohio Valley. Very large and deadly outbreak produced multiple killer tornadoes across the Ohio Valley and Southeastern United States. A violent F4 hit Van Wert, Ohio, killing four people. Deadly F3 also hit Mossy Grove, Tennessee, killing seven.
67 tornadoes: November 23–24, 2001, Southeast U.S. Thirteen people killed.
50 tornadoes: November 15, 2005, Central and Southeast U.S. One person killed.
50 tornadoes: November 15 - 16, 1987, Oklahoma, Texas, and Mississippi.

Wunderground weather historian Christopher C. Burt has more detail on November tornado history in his latest post.


Figure 2. MODIS image of Extratropical Storm Cleopatra/Ruven off the coast of Sardinia, taken at approximately 15:30 UTC (10:30 am EST) November 19, 2013. Image credit: NASA.

Extreme flooding kills 17 in Sardinia, Italy
Slow-moving and powerful Extratropical Storm Cleopatra (called Ruven by the Free University of Berlin) dumped prodigious rains over the Mediterranean island of Sardinia on Monday, triggering floods that have killed at least seventeen people. According to media reports, the storm dumped as much as 450 mm (17.72") of rain in just 24 hours on the Italian island. The storm brought sustained winds of 38 mph, gusting to 56 mph, to Cagliari, Sardinia, on Monday.


Figure 3. MODIS image of Subtropical Storm Melissa, taken at approximately 13:30 UTC (8:30 am EST) November 19, 2013. Image credit: NASA.

Subtropical Storm Melissa no threat to land
Subtropical Storm Melissa, the 13th Atlantic named storm of 2013, is slowly transitioning to a tropical storm as it heads north over the Central North Atlantic, far from land. Ocean temperatures are near 25°C, which is barely warm enough to support a tropical storm, but wind shear is a moderate 10 - 20 knots, which may allow Melissa to become fully tropical by Wednesday morning. Wind shear is expected to rise to the high range on Wednesday as ocean temperatures plummet to 20°C (68°F) and dry air sharply increases. These conditions should cause Melissa to rapidly deteriorate on Wednesday. Satellite loops show that Melissa has a large circulation, but only limited heavy thunderstorm activity near the center. Melissa will not be a threat to any land areas.

Jeff Masters

Severe Weather Tornado Flood

Rare November Tornado Outbreak Kills 6; Subtropical Storm Melissa Forms

By: JeffMasters, 3:23 PM GMT on November 18, 2013

A rare and deadly late-season tornado and severe weather outbreak blitzed the Midwest U.S. on Sunday, killing at least six people and leaving widespread significant damage. A tornado preliminarily rated as a violent EF-4 touched down in New Minden, Illinois, east of St. Louis, carving a path of destruction three miles long, killing two people, and blowing semi trucks off of I-64. The twister was one of only twenty EF-4s to occur in the U.S. in November dating back to 1950, and was the third most northerly November EF-4 ever observed, according to data from the Tornado History Project. The most widespread damage from Sunday's outbreak occurred in the town of Washington (population 16,000), about 140 miles southwest of Chicago, where another powerful EF-4 tornado destroyed or heavily damaged 250 - 500 homes and an apartment complex. A northern Illinois man says he discovered mail belonging to Washington residents on his property in Channahon, about 80 miles northeast Washington, according to the (Peoria) Journal-Star. Three other tornado deaths occurred in Massac County in the far southern part of Illinois, making Sunday the deadliest November tornado outbreak in Illinois history. NOAA's Storm Prediction Center logged 68 preliminary tornado reports, along with 412 reports of high wind gusts and 32 reports of hail. Sixteen of the wind gusts were in excess of 74 mph (hurricane strength.)


Figure 1. A view of part of Washington, Illinois from Mackenzie Street on Sunday, Nov. 17, 2013 after a tornado tore through the area. (AP Photo/Alex Kareotes)


Figure 2. Radar reflectivity image of the supercell thunderstorm that spawned the Washington, Illinois tornado of November 17, 2013.

A strange 2013 tornado season
Sunday's tornado outbreak is yet another anomaly in what has been a very unusual 2013 tornado season. The top three tornado outbreaks have occurred in November, January, and October--well outside the usual spring/summer peak of tornado season:

Top Five Tornado Days of 2013
------------------------------------------
01/29/13: 62 tornadoes
11/17/13: 68 (filtered) tornadoes, but likely to decrease once damage surveys completed
10/31/13: 42 tornadoes
05/20/13: 32 tornadoes
05/31/13: 30 tornadoes

It's been an unusually slow severe weather season, with the 2013 preliminary tally of 818 tornadoes before Sunday the lowest year-to-date count since the extreme drought year of 1988. However, when severe weather outbreaks have come, they have been unusually destructive. According to Aon Benfield, there have been five severe weather outbreaks topping $1 billion in damages this year. This is the third highest number of such disasters on record, going back to 1980. The record is shared by 2011 and 2012, with seven billion-dollar-plus severe weather outbreaks, according to NOAA's National Climatic Data Center. According to Aon Benfield, "prior to Sunday’s outbreak, both economic and insured losses attributed to severe weather were slightly below the 10-year average in 2013. Thus far, economic losses from convective storm events were roughly USD15.7 billion and approximately USD9.2 billion of those losses were covered by insurance. The 2003-2012 averages are USD17 billion and USD11 billion, respectively. It remains too early to project losses from Sunday’s event." The most expensive and deadliest severe weather outbreak of 2013 hit on May 20, when Moore, Oklahoma was devastated by an EF-5 tornado that killed 23 people and did $2 billion in damage. Yesterday's damage was severe and widespread, and there is a good chance the outbreak will become the first-ever billion-dollar severe weather outbreak to hit in November.


Figure 3. Prior to Sunday's severe weather outbreak, there were seven billion-dollar weather disasters in the U.S. in 2013. Five of these disasters were severe weather outbreaks--the third highest such total in history.

November tornado outbreaks: how rare?
Since 1950, there have been 2211 November tornadoes, killing 251 and injuring 5060.

Deadliest: 24 killed, 11/06/2005, F-3 tornado near Evansville, Indiana
Longest path: 160 miles, 11/23/1992, F-3 tornado in North Carolina
Most November tornadoes: 154 in 2004 (both 2005 and 1992 had 153)

Here is a list of the largest November tornado outbreaks since 1950:

95 tornadoes: November 21–23, 1992, Texas to Mississippi and into the Ohio Valley. The most intense and largest November outbreak on record in U.S. history. Produced violent tornadoes from Texas to Mississippi and into the Ohio Valley, including six F4s and two extremely long-track tornadoes, 160 miles and 128 miles.
75 tornadoes: November 9–11, 2002, Southeast U.S. and Ohio Valley. Very large and deadly outbreak produced multiple killer tornadoes across the Ohio Valley and Southeastern United States. A violent F4 hit Van Wert, Ohio, killing four people. Deadly F3 also hit Mossy Grove, Tennessee, killing seven.
67 tornadoes: November 23–24, 2001, Southeast U.S. Thirteen people killed.
50 tornadoes: November 15, 2005, Central and Southeast U.S. One person killed.
50 tornadoes: November 15 - 16, 1987, Oklahoma, Texas, and Mississippi
46 tornadoes: November 27–28, 2005, Central and Southeast U.S. One person killed.
44 tornadoes: November 15, 1988, Central and Eastern U.S.
40 tornadoes: November 15 - 16, 1989, Produced a deadly F4 that struck Huntsville, Alabama, at rush hour. Strong tornadoes touched down as far north as Quebec.

Sunday's outbreak will probably rank as the fourth most prolific November tornado outbreak since 1950. But what was really remarkable about the outbreak was how far north it extended, with severe thunderstorms and tornado warnings issued in Wisconsin and Michigan. NWS Gaylord has confirmed an EF-0 at I-75 near Waters yesterday, which closed the highway. This is the farthest north there's been a tornado in Michigan in November or this late in the year in the period of modern tornado records (1950-present), and only the seventh November tornado recorded in Michigan. In Southeast Lower Michigan where I live, I've never seen such a powerful and long-lasting high wind event during the 40 years I've lived here. As I sawed up the downed tree blocking my street last night, accompanied by wild winds, flashing lightning, and the eerie orange glow of a nearby electrical transformer blowing, I reflected once again how the severe weather season has become increasingly noticeable in cold season months here. These events are rare enough and our database is so poor that we can't make any definitive statements on how climate change may be affecting them, but one would expect to see cold-season severe weather events become increasingly common farther to the north in a warming climate. According to the Chicago NWS, prior to Sunday’s tornado outbreak, there had been just twelve November tornadoes since 1950 in the 23-county region of Northeast Illinois and Northwest Indiana that they service (six of these twisters touched down on November 12, 1965.) Preliminary tornado reports indicate that as many as six tornadoes may touched down Sunday in the region (four in Will County, one in Grundy County, and one in Newton County.) November tornadoes tend to be strong and destructive, and any shift to a climate with more of these beasts will be unwelcome. The Chicago NWS wrote: "Eight of the twelve previous November tornadoes were EF-2 or stronger, showing that when tornadoes do occur in November, there is a decent likelihood they will be significant (EF-2 or stronger). The primary reason for this is strong dynamics and wind field that tend to be present in the cool season (late autumn and winter), which add to a greater amount of wind shear.  This is a key component to tornadoes, and the greater the wind shear the more likelihood for significant tornadoes."


Figure 4. MODIS image of Subtropical Storm Melissa, taken at 13:30 UTC (8:30 am EST) November 18, 2013. Image credit: NASA.

Subtropical Storm Melissa forms
A large low pressure system centered about 740 miles east-southeast of Bermuda acquired enough organization to become Subtropical Storm Melissa, the 13th Atlantic named storm of 2013. The storm is generating sustained winds in excess of tropical storm force, as seen on the latest ASCAT satellite wind map. Ocean temperatures are near 27°C, which is about 1°C above average, and plenty warm enough to support tropical storm formation. While wind shear is currently a high 30 - 40 knots, it is expected to drop to the moderate range on Tuesday before increasing again on Wednesday. Satellite loops show that Melissa has a large band of heavy thunderstorms displaced more than 100 miles from the center of circulation, which is characteristic of a subtropical storm. Heavy thunderstorm activity near the center is beginning to build, so it is possible that NHC would classify this system as Tropical Storm Melissa on Tuesday. Melissa will not be a threat to any land areas.

Jeff Masters

Tornado Hurricane Severe Weather

Dangerous 'High Risk' Midwest U.S. Tornado Outbreak Underway

By: JeffMasters, 4:30 PM GMT on November 17, 2013

A rare and very dangerous late-season severe weather outbreak is underway over the Midwest U.S., where NOAA's Storm Prediction Center is predicting a "High Risk" of severe weather--their highest level of alert--over most of Indiana and Illinois, plus portions of Southern Lower Michigan and Western Ohio. This is just the second "High Risk" forecast for 2013, and the area at risk of severe weather is unusually large. According to a list of all "High Risk" forecasts issued since 1984 maintained at Wikipedia, today's High Risk area is the farthest north such a forecast has been issued so late in the year. A 992 mb low pressure system that was over Northern Illinois on Sunday morning will move northeast and rapidly intensify to 965 mb by Monday morning, dragging a strong cold front across the "High Risk" area on Sunday afternoon. Isolated supercell thunderstorms--the kind most likely to produce strong and violent tornadoes--are expected to form ahead of the front, and the SPC is expecting multiple long-track strong tornadoes to form during the early afternoon. Any tornadoes that form will be moving at highway speed--50 to 60 mph--and will be under low cloud bases around 2,000 feet, making these storms difficult to see and react to, particularly in wooded or hilly areas. If the sirens sound, seek shelter!


Figure 1. Severe weather outlook for Sunday, November 17, 2013.

A dangerous day in Chicago
Most of Illinois, including Chicago, has been placed under a special "PDS" Tornado Watch: a "Particularly Dangerous Situation." Severe thunderstorms spawning tornado warnings have already erupted over Southern Wisconsin and Western Illinois as of 10:15 am CST. Severe thunderstorms are likely to sweep through Chicago in the early afternoon during today's Ravens - Bears game, which starts at noon CST. According to NBC 5 in Chicago, loose objects are being removed from the stadium in anticipation of high winds, and officials are prepared to evacuate fans, if necessary. An NFL game will stop if there is lightning, and cannot continue until 30 minutes afterwards.


Figure 2. Prior to Sunday's severe weather outbreak, there were seven billion-dollar weather disasters in the U.S. in 2013. Five of these disasters were severe weather outbreaks--the third highest such total in history.

A slow but very expensive tornado season
It's been an unusually slow severe weather season, with the 2013 preliminary tally of 818 tornadoes the lowest year-to-date count since the extreme drought year of 1988. However, when severe weather outbreaks have come, they have been unusually destructive. According to Aon Benfield, there have been five severe weather outbreaks topping $1 billion in damages this year. This is the third highest number of such disasters on record, going back to 1980. The record is shared by 2011 and 2012, with seven billion-dollar-plus severe weather outbreaks, according to NOAA's National Climatic Data Center. The total damage from 2013's five billion-dollar severe weather outbreaks is $14 billion, which is the third highest on record, behind 2011 ($29.6 billion) and 2010 ($16.3 billion.) The most expensive and deadliest severe weather outbreak of 2013 hit on May 20, when Moore, Oklahoma was devastated by an Ef-5 tornado that killed 23 people and did $2 billion in damage.

Stay Safe!
November is a highly unusual time to be getting a dangerous severe weather outbreak, but people need to take this event seriously. The four previous November "High Risk" events (1989, 1994, 2002, and 2005) have resulted in a total of 148 tornadoes and 62 fatalities (thanks go to wunderground member Neapolitan for this stat). Stay Safe!

Jeff Masters

Tornado

Haiyan's True Intensity and Death Toll Still Unknown

By: JeffMasters, 5:10 PM GMT on November 15, 2013

A full week after one of the strongest tropical cyclones in world history devastated the Philippines, the full extent of the death and destruction wrought by Super Typhoon Haiyan is still not fully known, nor do we have actual ground measurements of the storm's peak winds and lowest pressure. The Philippines ‪National Disaster Risk Reduction and Management Council‬ estimates 3432 people were killed, and the U.N. puts this number at 4,460. This makes Haiyan the 2nd deadliest Philippines tropical cyclone in history, behind Tropical Storm Thelma of 1991, which killed 5081 - 8165 people. Damage is estimated at $12 - $15 billion, or about 5% of the Philippines' GDP.


Figure 1. Infrared VIIRS image of the eye of Haiyan taken at 16:19 UTC November 7, 2013. At the time, Haiyan was at peak strength with 195 mph sustained winds. Image credit: NOAA/CIRA.

What was Haiyan's lowest pressure?
The Japan Meteorological Agency (JMA) estimated that Haiyan's central pressure was 895 mb at landfall, which would make it the 12th strongest tropical cyclone in world history (by pressure.) We now have pressure measurements from Haiyan's second landfall in Tacloban, where a group of storm chasers deployed two high-quality Kestrel pressure instruments in the Hotel Alejandro, in the heart of the Downtown district (11.2414N 125.0036E.) This location was about eighteen miles north of the center of the eye, and did not receive the typhoon's strongest winds, which probably occurred about two miles to the south, judging by the zoomed-in radar image from landfall (Figure 3.) Josh Morgerman of iCyclone.com was kind enough to send me plots of the data recorded from their instruments. Device 1 measured a minimum pressure of 960.8 mb at 7:12 am, and their Device 2 measured 960.3 mb at 7:20 am. Josh talked to a source at the Tacloban Airport, located about 1 mile farther to the south, who said that the airport measured 955.6 mb at 7:15 am, before power was lost. These readings suggest that Haiyan had a pressure gradient of about 4 mb per mile. If we assume the airport was 17 miles north of the center of the eye, and there was a 4 mb/mile pressure gradient, Haiyan could have had an 888 mb central pressure. An email I received from NHC hurricane specialist Dr. Jack Beven documented several cases of Category 5 tropical cyclones with extreme pressure gradients:

Hurricane Andrew, 1992 (South Florida): 60 mb in 14 miles (4.3 mb/mile)
Hurricane Wilma, 2005 (in Caribbean): 94 mb in 14 miles (6.7 mb/mile)
Super Typhoon Megi, 2010 (east of Philippines): 60 mb in 14 miles (4.6 mb/mile)
September 1933 hurricane (ship measurement): 45 mb in 6 miles (7.5 mb/mile)
Hurricane Felix, 2007 (in Caribbean): 63 mb in 14 miles (4.5 mb/mile)

So, it is certainly possible that Haiyan had a pressure below 900 mb, but we will probably never know for certain.


Figure 2. Pressure observed in downtown Tacloban during the passage of Super Typhoon Haiyan on November 8, 2013 by Josh Morgerman of iCyclone.com. This sensor bottomed out at 960.3 mb at 7:20 am, at a location a few miles north of the northern edge of the eye. If we look at the Tacloban airport pressure readings in the last 3 hours they sent data on November 8, the readings were 1001.1 mb, 1000.9 mb, and 997.3 mb at 12 am, 1 am, and 2 am, respectively. The iCyclone instrument recorded 1002 mb, 1000 mb, and 998 mb at those times, so the two instruments agreed to within 1 mb.


Figure 3. Radar image of Super Typhoon Haiyan over Tacloban, on November 8, 2013. Tacloban was in the north (strongest) portion of Haiyan's eyewall, at a time when the typhoon's top sustained winds over water were estimated at 185 mph. Image credit: http://climatex.ph.

How strong were Haiyan's winds at initial landfall in Guiuan?
Haiyan's strongest winds occurred on the south shore of Samar Island and the city of Guiuan (population 47,000), where the super typhoon initially made landfall with 1-minute average winds estimated at 195 mph. This estimate came from the Joint Typhoon Warning Center (JTWC), and was based on satellite measurements. We have no ground level or hurricane hunter measurements to verify this estimate. The Japan Meteorological Agency (JMA), which uses their own techniques to estimate typhoon strength via satellite imagery, put Haiyan's peak strength at 125 knots (145 mph), using a 10-minute averaging time for wind speeds. The averaging time used by JTWC and NHC is 1-minute, resulting in a higher wind estimate than the 10-minute average winds used by JMA and PAGASA in their advisories. To convert from 10-minute averaged winds to 1-minute average, one conversion factor that is commonly used is to multiply by 1.14--though lower conversion factors are sometimes used. JMA satellite strength estimates are consistently much lower than those from JTWC for high-end Category 5 strength typhoons; JTWC estimates are the ones most commonly used by the hurricane research community. A searchable database going back to 1976 of the JMA typhoon information available at Digital Typhoon reveals that Haiyan is tied for second place as the strongest typhoon that JMA has rated, and was the strongest landfalling typhoon, when measured by wind speed. The only typhoon they rated as stronger was Super Typhoon Tip of 1979, but that storm weakened to Category 1 strength before making landfall in Japan.


Figure 4. The 400-year-old Church of the Immaculate Conception (left) collapsed in Guiuan, Philippines, during Super Typhoon Haiyan. Image credit: J.B. Baylon and http://chuvaness.com/.

Typhoon and hurricane maximum wind speed estimates are only valid for over water exposure, and winds over land are typically reduced by about 15%, due to friction. This would put Haiyan's winds at 165 mph over land areas on the south shore of Samar Island. This is equivalent to a high end EF-3 tornado. Forty minutes before landfall, the airport in Guiuan reported sustained 10-minute average winds of 96 mph, with a pressure of 977 mb, before contact was lost. damage photos of Guiuan show at least EF-2 scale damage (111 - 135 mph winds): Roofs torn off well-constructed houses; foundations of frame homes shifted; mobile homes completely destroyed; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground. The mayor of the city had his car lifted off the ground and slammed into a building, which is consistent with at least EF-2 damage. There is possible EF-3 damage (136-165 mph winds) in the Guiuan damage photos, with the 400-year-old stone Church of the Immaculate Conception collapsed, and a bus toppled. EF-3 damage is defined as: Entire stories of well-constructed houses destroyed; severe damage to large buildings such as shopping malls; trains overturned; trees debarked; heavy cars lifted off the ground and thrown; structures with weak foundations blown away some distance. A detailed damage survey would be need to determine if EF-3 winds really did occur in Guiuan.

Haiyan Links
Wunderblogger Lee Grenci discusses mesovorticies in the eye of Haiyan in his latest post.
Wunderground's weather historian Christopher C. Burt reviews the Philippine's typhoon history.
The University of Wisconsin CIMSS Satellite Blog has a great collection of satellite images of Haiyan.
NOAA's Michael Folmer has a post showing the unusual burst of lightning that occurred at landfall in Haiyan.
Hurricanes and Climate Change: Huge Dangers, Huge Unknowns, my August 2013 blog post.
Storm Chaser James Reynolds on Twitter, from Tacloban, Leyte.
Storm Chaser Jim Edds on Twitter, from Tacloban, Leyte.
Storm Chaser Josh Morgerman (iCyclone) on Facebook

The Philippine Red Cross is appealing for donations.

Portlight disaster relief charity is reaching out to disability organizations in the Philippines to provide durable medical equipment. and welcomes donations.


Figure 5. "Tipping Points" host Bernice Notenboom goes on a sled adventure in Greenland.

New "Tipping Points" episode, "Greenland Ice-sheet Melt", airs Saturday at 9 pm EDT/8 pm CDT
“Tipping Points”, the landmark 6-part climate change TV series that began airing in October on The Weather Channel, airs for the fifth time on Saturday night, November 16, at 9 pm EDT. The new episode, "The Greenland Ice-sheet Melt", goes on an expedition to the remote Inuit village of Qaanaaq to explore the rate Greenland Ice sheet melt and its effects on global ocean circulation. I make a short appearance 8 minutes into the episode to report on how much ice Greenland has lost in the past decade. The series is hosted by polar explorer and climate journalist Bernice Notenboom, the first woman to perform the remarkable triple feat of climbing Mt. Everest and walking to the North and South Poles. In each episode, Notenboom heads off to a far corner of the world to find scientists in the field undertaking vital climate research to try to understand how the climate system is changing and how long we have to make significant changes before we reach a tipping point--a point of no return when our climate system will be changed irreversibly.

Have a great weekend, everyone, and I'll be back Monday with a new post.

Jeff Masters

Hurricane

Super Typhoon Haiyan's Intensification and Unusually Warm Sub-Surface Waters

By: JeffMasters, 6:25 PM GMT on November 13, 2013

A remarkable warming of the sub-surface Pacific waters east of the Philippines in recent decades, due to a shift in atmospheric circulation patterns and ocean currents that began in the early 1990s, could be responsible for the rapid intensification of Super Typhoon Haiyan. Hurricanes are heat engines, which means they take heat energy out of the ocean, and convert it to kinetic energy in the form of wind. It's well-known that tropical cyclones need surface water temperatures of at least 26.5°C (80°F) to maintain themselves, and that the warmer the water, and the deeper the warm water is, the stronger the storm can get. Deep warm water is important, since as a tropical cyclone tracks over the ocean, it stirs up cooler water from the depths, potentially reducing the intensity of the storm. When both Hurricane Katrina and Hurricane Rita exploded into Category 5 hurricanes as they crossed over a warm eddy in the Gulf of Mexico with a lot of deep, warm water, the concept of the total heat energy available to fuel a hurricane--the Tropical Cyclone Heat Potential (TCHP)--became one that gained wide recognition. The Pacific Ocean east of the Philippines has the largest area of deep, warm water of anywhere on Earth, and these waters have historically fueled the highest incidence of Category 5 storms of anywhere on the planet. Super Typhoon Haiyan tracked over surface waters that were of near-average warmth, 29.5 - 30.5°C (85 - 87°F.) However, the waters at a depth of 100 meters (328 feet) beneath Haiyan during its rapid intensification phase were a huge 3°C above average, according to Professor I-I Lin of the Department of Atmospheric Science at the National Taiwan University. An analysis by the Japan Meteorological Agency for October showed ocean temperatures 4 - 5°C (7 - 9°F) above average during October (Figure 1). This analysis was from a model. When looking at actual measurements made by the Argo float data in early November, the temperatures in the layer 100 meters below the surface under Haiyan were about 3°C above average, not 4 - 5°C, according to Dr. Lin. As the typhoon stirred this unusually warm water to the surface, the storm was likely able to feed off the heat, allowing Haiyan to intensify into one of the strongest tropical cyclones ever observed.


Figure 1. Modeled departure of temperature from average at a depth of 100 meters in the West Pacific Ocean during October 2013, compared to a 1986 - 2008 average. The track and intensity of Super Typhoon Haiyan are overlaid. Haiyan passed directly over large areas of sub-surface water that were much above average in temperature, which likely contributed to the storm's explosive deepening. While this model showed 4 - 5°C departures from average in October, the actual values were closer to 3°C in early November, according to Argo float data. Image credit: Japan Meteorological Agency.

Why was there such unusually warm sub-surface water?
The sub-surface waters east of the Philippines have warmed dramatically over the past twenty years. According to Pun et al. (2013), "Recent increase in high tropical cyclone heat potential area in the Western North Pacific Ocean", the depth to where ocean temperatures of at least 26°C (79°F) penetrates has increased by 17% since the early 1990s, and the Tropical Cyclone Heat Potential has increased by 13%. The warm-up is due to an increase in the surface winds blowing across the region--the trade winds--which have caused a southward migration and strengthening of the North Equatorial Current (NEC) and the North Equatorial Counter Current (NECC). The strong trade winds have pushed a large amount of water up against the east coast of the Philippines in the past twenty years, resulting in a rate of sea level rise of 10 mm per year--more than triple the global average of 3.1 mm/yr (Figure 2.) This extra sea level rise contributed to the storm surge damage from Super Typhoon Haiyan. Sea level rise data from Legaspi in the Eastern Philippines shows a rise of about 305 mm (12 inches) since 1949. For comparison, global average sea level rose 7.5" (190 mm) since 1901. Part of the rise along the eastern Philippine coast is from tectonic processes--the subsidence of the Philippine plate under the Eurasian plate--but most of it is due to the stronger trade winds piling up warm water along the coast, and the fact that warmer waters expand, raising sea level.


Figure 2. Trend in sea level from satellite altimeter measurements in 1993 - 2010. Black lines are the Sea Surface Height (SSH) in cm from Rio et al. (2009.) Image credit: Qiu, B., and S. Chen, 2012, "Multidecadal sea level and gyre circulation variability in the northwestern tropical Pacific Ocean", Journal of Physical Oceanography 42.1 (2012): 193-206.

Why have the trade winds sped up?
The surface trade winds in the equatorial Pacific are part of the Walker Circulation--a pattern of rising and sinking air along the Equator that the El Nino/La Nina cycle influences. A strong Walker circulation means there is lower pressure over Indonesia, which pulls in more air at the surface along the Equator from the east, increasing the easterly trade winds. As these trade winds strengthen, they pull surface ocean waters away from South America, allowing cold water to upwell to the surface. This is a La Niña-like situation, which takes heat energy out of the atmosphere, putting it into the ocean, keeping global surface temperatures cooler than they would otherwise be. A weakened Walker circulation is the reverse, resulting in weaker trade winds, and a more El Niño-like situation with higher global surface temperatures. As long as the stronger Walker circulation that has been in place since the early 1990s holds, global surface temperatures should stay cooler than they otherwise would be, prolonging the slow-down in global surface warming that has received much attention this year. There may also be a greater chance of super typhoons and higher storm surges affecting the Philippines, due to the warmer sub-surface waters and re-arranged ocean currents. A 2013 paper by L’Heureux et al. notes that the climate models predict that the Walker circulation should weaken (a more El Niño-like situation)--the reverse of what has been observed the past twenty years. The researchers took the observed pressure patterns over the Pacific in recent decades and removed the atmospheric response to the El Niño/La Niña cycle. The resulting pattern they found showed a steady strengthening of the Walker circulation, in concert with global rising temperatures. So, are we seeing a failure of the climate models? Or is the recent speed-up of the Walker circulation a decades-long temporary "speed bump" in the climate system? Time will tell. It is worth pointing out that a just-released paper by British and Canadian researchers shows that the global surface temperature rise of the past 15 years has been greatly underestimated. As discussed at realclimate.org, "The reason is the data gaps in the weather station network, especially in the Arctic. If you fill these data gaps using satellite measurements, the warming trend is more than doubled in the widely-used HadCRUT4 data, and the much-discussed “warming pause” has virtually disappeared."

I appeared on PBS Newshour last night to discuss the linkages between stronger tropical cyclones and climate change, video here.

References
L’Heureux, Michelle L., Sukyoung Lee, and Bradfield Lyon, 2013, "Recent multidecadal strengthening of the Walker circulation across the tropical Pacific", Nature Climate Change 3.6 (2013): 571-576.

Pun, Iam‐Fei, I‐I. Lin, and Min‐Hui Lo, 2013, "Recent increase in high tropical cyclone heat potential area in the Western North Pacific Ocean", Geophysical Research Letters (2013).

Qiu, B., and S. Chen, 2012, "Multidecadal sea level and gyre circulation variability in the northwestern tropical Pacific Ocean", Journal of Physical Oceanography 42.1 (2012): 193-206.

Jeff Masters

Hurricane Climate Change

Haiyan is Dead, Better Weather Ahead for the Philippines; 'We Can Stop This Madness'

By: JeffMasters, 3:44 PM GMT on November 12, 2013

Super Typhoon Haiyan is gone, but not before adding China to its list of ravaged nations in Asia. Haiyan made landfall on the northern Vietnam coast near the Chinese border as a Category 1 storm with 75 mph winds on Sunday, and spread torrential rains into southern China of up to 38 centimeters (15 inches) over some parts of Guangxi province, which caused up to $700 million in damage to agricultural, forestry, poultry and fishing industries there, said China National Radio. Seven people were killed in China on hard-hit Hainan Island, with three others missing. At least 13 people died and 81 were injured in Vietnam from the storm, said the Voice of Vietnam, the country's national radio broadcaster. Huge 26-foot waves from Haiyan swept 16 people out to sea in Taiwan on Sunday, killing 8 of them, the Chinese news agency Xinhua reported. The devastation wrought by Haiyan in the Philippines is among the most severe punishments ever inflicted by a tropical cyclone in modern history. With an official death toll of 1,774, Haiyan already ranks as the 3rd deadliest typhoon in Philippine history. The deadliest typhoon in Philippine history was Typhoon Thelma of 1991, which killed between 5101 - 8000 people, reports wunderground's weather historian Christopher C. Burt in his latest post on Philippines typhoon history.


Figure 1. Col John Sanchez, Central Command, AFP took these photos from a PAF Nomad aircracft over Guiuan, E. Samar, on November 10, 2013: "Guiuan bore the brunt of Super Typhoon Yolanda at its first landfall Friday. One hundred percent of the structures either had their roofs blown away or sustained major damage. Nearly all coconut trees fell. We saw people in the streets, seemingly dazed. Trucks and cars were left in the streets where they were stopped in their tracks as Yolanda struck. We were probably the first outsiders to fly over the area since Friday and obviously, no relief goods have arrived there yet. It was almost lunchtime but there was no smoke from cooking fires. The 2.4 km runway is clear of debris and could still be used by C130 aircraft." Image credit: Col John Sanchez , Central Command, AFP.

Tropical disturbance 90W leaving the Philippines; better weather ahead
A tropical disturbance that passed over the Philippines Island of Mindanao (Invest 90W), brought heavy rains of 82 mm (3.2 inches) of rain in the 24 hours ending 8am Philippines time Tuesday (7pm Monday EST) to Davao City on Mindanao. Heavy rains fell over the disaster area in the Central Philippines, as well, hampering relief efforts. However, the storm is now leaving the islands, and water vapor satellite loops show a large area of dry air to the east of the Philippines. This will bring several days of dryer weather, with only scattered afternoon thunderstorms, to the disaster zone. The GFS model is not predicting any new tropical cyclones forming in the Western Pacific over the coming seven days. The Japan Meteorological Agency is still classifying 90W as a tropical depression, but the Philippines Atmospheric Geophysical and Astronomical Services Administration (PAGASA) has downgraded the depression (which they called Zoraida) to a remnant low, as of 3:30pm their time (2:30am EST.) The disturbance still has a high chance of development into a tropical depression, according to Tuesday's 06 UTC Western Pacific Tropical Weather Discussion by the Joint Typhoon Warning Center (JTWC).

Haiyan's place in history
Haiyan hit Guiuan, on the Philippine island of Samar, at 4:40 am local time November 8, 2013 (20:40 UTC November 7.) Three hours before landfall, the Joint Typhoon Warning Center (JTWC) assessed Haiyan’s sustained winds at 195 mph, gusting to 235 mph, making it the 4th strongest tropical cyclone in world history. Satellite loops show that Haiyan weakened only slightly, if at all, in the two hours after JTWC’s advisory, so the super typhoon likely made landfall with winds near 195 mph. The next JTWC intensity estimate, for 00Z UTC November 8, about three hours after landfall, put the top winds at 185 mph. Averaging together these estimates gives a strength of 190 mph an hour after landfall. Thus, Haiyan had winds of 190 - 195 mph at landfall, making it the strongest tropical cyclone on record to make landfall in world history. The previous record was held by the Atlantic's Hurricane Camille of 1969, which made landfall in Mississippi with 190 mph winds.

With Angela Fritz' help, I've put together a list of most intense world tropical cyclones at landfall, using the advisories taken from the National Hurricane Center in the Atlantic and the Joint Typhoon Warning Center in the rest of the world's oceans. Both agencies use 1-minute averaging times for their advisories, as opposed to the 10-minute averaging time used to report wind speeds by most international weather agencies and at most international airports. The list is unofficial and may have omissions; email me at jmasters@wunderground.com if you have suggestions for improvement:



"We can stop this madness"
At the annual United Nations talks on developing a global climate treaty, currently underway in Warsaw, Poland, Naderev Saño, the chief representative of the Philippines at the conference, said on Monday: “What my country is going through as a result of this extreme climate event is madness; the climate crisis is madness. We can stop this madness right here in Warsaw.” Saño promised to undergo a hunger strike in solidarity with the storm victims until “a meaningful outcome is in sight.”

I've blogged extensively about the links between hurricanes, typhoons, and climate change, most recently in my August 2013 post, Hurricanes and Climate Change: Huge Dangers, Huge Unknowns. Since hurricanes are heat engines that take heat energy from the oceans and convert it to the energy of their winds, rising ocean temperatures due to global warming should make the strongest storms stronger, though the poor quality and relatively short length of the global database of hurricanes and typhoons make it difficult to tell if this has already begun to occur. Hurricane scientists expect to see a 2% - 11% increase in the intensity of hurricanes and typhoons (aka tropical cyclones) by 2100. Later this week, I'll have a more detailed look at the conditions that helped fuel the incredible strength of Super Typhoon Haiyan, and discuss possible linkages to climate change.


Video 1. After Super Typhoon Haiyan ravaged the Philippines, climate change representative Yeb Sano pleaded with the world to take immediate, drastic action to reduce climate change-causing carbon dioxide emissions in an emotional speech at the UN's climate meeting in Warsaw, Poland.

The Philippine Red Cross is appealing for donations.

Portlight disaster relief charity is reaching out to disability organizations in the Philippines to provide durable medical equipment. and welcomes donations.

Jeff Masters

Hurricane

Haiyan Finally Dying; Somalia's Deadliest Tropical Storm on Record Kills 100

By: JeffMasters, 5:07 PM GMT on November 11, 2013

Typhoon Haiyan made landfall on the northern Vietnam coast near the Chinese border as a Category 1 storm with 75 mph winds near 21 UTC Sunday. At least 13 people died and 81 were injured in Vietnam from the storm, said the Voice of Vietnam, the country's national radio broadcaster. Satellite loops show that Haiyan has now pushed into Southeastern China, where 4 - 8" of rain will likely cause moderate flooding. Huge 26-foot waves from Haiyan swept 16 people out to sea in Taiwan on Sunday, killing 8 of them, the Chinese news agency Xinhua reported. Haiyan has been downgraded to a tropical depression and will dissipate later today, finally bringing to an end its catastrophic march through Asia.


Figure 1. Tropical Storm Haiyan over China, as seen by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua satellite at 05:45 UTC on November 11, 2013. Image credit: NASA.

Third deadliest typhoon in Philippines history
With an official death toll of 1,774, Haiyan already ranks as the 3rd deadliest typhoon in Philippine history. The deadliest typhoon in Philippine history was Typhoon Thelma of 1991, which killed between 5101 - 8000 people, reports wunderground's weather historian Christopher C. Burt in his latest post on Philippines typhoon history. The greatest death toll from Haiyan is likely to be in the capital of Leyte, Tacloban (population 221,000), which received a direct hit from Haiyan's northern eyewall.


Figure 2. In this handout from the Malacanang Photo Bureau, an aerial view of buildings destroyed in the aftermath of Typhoon Haiyan on November 10, 2013 over the Leyte province. (Getty/Malacanang Photo Bureau)

Tropical disturbance 90W bringing heavy rain to the Philippines
A tropical disturbance centered about 200 miles east of the Philippines Island of Mindanao (Invest 90W), is bringing heavy rains to Mindanao, and has the potential to become a tropical depression by Tuesday. The disturbance has developed an elongated surface circulation and a respectable amount of heavy thunderstorm activity. Wind shear is low, but the disturbance is too close to the Equator intensify quickly, since the storm will not be able to leverage Earth's spin to get itself spinning. The disturbance has a high chance of development, according to Monday's 06 UTC Western Pacific Tropical Weather Discussion by the Joint Typhoon Warning Center (JTWC). The heaviest rains of 3 - 6" from 90W will stay to the south of the typhoon-devastated areas of the Central Philippines, but 2 - 4" of rain could fall in the disaster zone on Tuesday and Wednesday, hampering relief efforts. I give a 70% chance that 90W will be classified as a tropical depression by JTWC by Tuesday. The Japan Meteorological Agency is already classifying 90W as a tropical depression, and the system is being referred to as Tropical Depression Zoraida by the Philippines Atmospheric Geophysical and Astronomical Services Administration (PAGASA.)

How strong were Haiyan's winds?
Haiyan's strongest winds occurred on the south shore of Samar Island and the city of Guiuan (population 47,000), where the super typhoon initially made landfall with 1-minute average winds estimated at 195 mph. This estimate came from the Joint Typhoon Warning Center, and was based on satellite measurements. We have no ground level or hurricane hunter measurements to verify this estimate. Typhoon and hurricane maximum wind speed estimates are only valid for over water exposure, and winds over land are typically reduced by about 15%, due to friction. This would put Haiyan's winds at 165 mph over land areas on the south shore of Samar Island. This is equivalent to a high end EF-3 tornado, and damage photos from the town do appear to show EF-3 damage--though much of the worst damage appears to be due to the storm surge. A new Doppler radar that was scheduled to go into operation in 2014 was blown off the tower it was installed on in Guiuan, and was not operational during the storm, unfortunately.

The Japan Meteorological Agency (JMA), which uses their own techniques to estimate typhoon strength via satellite imagery, put Haiyan's peak strength at 125 knots (145 mph), using a 10-minute averaging time for wind speeds. The Philippines weather agency (PAGASA) also uses a 10-minute averaging time for their typhoon wind advisories, and also had a lower estimate of Haiyan's winds. Winds estimated by either JMA or PAGASA for Haiyan have appeared in the media, resulting in some confusion about what the typhoon's winds were at landfall. The averaging time used by JTWC and NHC is 1-minute, resulting in a higher wind estimate than the 10-minute average winds used by JMA and PAGASA in their advisories. To convert from 10-minute averaged winds to 1-minute average, one conversion factor that is commonly used is to multiply by 1.14--though lower conversion factors are sometimes used.

JMA satellite strength estimates are consistently much lower than those from JTWC for high-end Category 5 strength typhoons, and JTWC estimates are the ones most commonly used by the hurricane research community. The JMA began issuing typhoon advisories in 1976, and a searchable database of their typhoon database at digitaltyphoon.com reveals that Haiyan is tied for second place as the strongest typhoon in history, when measured by wind speed. Haiyan was the strongest landfalling typhoon they have rated.

I asked Stormchaser Jim Edds, who rode out the storm at a hotel in Tacloban, what the lowest pressure reading he took was from his hand-held pressure sensor. You can watch his remarkable eyewall video, available here. At one point during the ordeal, he was forced to jump into the hotel pool to escape wind-blown debris. Via email, he told me, "My barometer stopped after I jumped in the pool.  It wasn't waterproof but I recall it was 972 mb but the storm got a whole lot worse and I had a chance to get out of the pool and make a run for it." He just posted a new video showing the aftermath of the devastating storm. A second group of storm chasers in Tacloban, James Reynolds, Josh Morgerman and Mark Thomas, did record pressure data, and will make graphs of the data available on Tuesday.


Video 1. Storm chasers James Reynolds, Josh Morgerman and Mark Thomas were in the capital of Leyte Province, Tacloban, which received a direct hit from Super Typhoon Haiyan. This video shows some of the extreme winds of the eyewall, as filmed by James Reynolds. You can read an account of their escape from Tacloban on CNN.


Video 2. Aftermath of Haiyan in Tacloban, as filmed by James Reynolds.

The Philippine Red Cross is appealing for donations.

Portlight disaster relief charity is reaching out to disability organizations in the Philippines to provide durable medical equipment. and welcomes donations.

Google Person Finder: Typhoon Yolanda - Google.org

Haiyan Links
Wunderblogger Lee Grenci discusses mesovorticies in the eye of Haiyan in his latest post.
Wunderground's weather historian Christopher C. Burt reviews the Philippine's typhoon history.
The University of Wisconsin CIMSS Satellite Blog has a great collection of satellite images of Haiyan.
NOAA's Michael Folmer has a post showing the unusual burst of lightning that occurred at landfall in Haiyan.
Hurricanes and Climate Change: Huge Dangers, Huge Unknowns, my August 2013 blog post.
Storm Chaser James Reynolds on Twitter, from Tacloban, Leyte.
Storm Chaser Jim Edds on Twitter, from Tacloban, Leyte.


Figure 3. Tropical Cyclone 3A over Somalia, as seen by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra satellite at 07:35 UTC on November 11, 2013. Image credit: NASA.

Rare tropical storm kills 100 in Somalia
Tropical Storm Three in the Arabian Sea made landfall in Somalia, Africa on Sunday, bringing sustained winds of 45 mph to the coast and heavy rains inland. The rains triggered flash floods that killed about 100 people, said President Abdirahman Mohamud Farole. According to the International Disaster Database, EM-DAT, this is the deadliest tropical cyclone in Somalia's history, tied with Tropical Cyclone ARB04 of 1994. According to the International Best Track Archive of storm tracks, only four other tropical storms have hit Somalia since accurate satellite measurements began in 1966: Tropical Cyclone Murjan of 2012, Tropical Cyclone ARB04 of 1994, Tropical Cyclone 12A of 1994, and Tropical Cyclone 4B of 1984.

Jeff Masters

Hurricane

Category 1 Typhoon Haiyan Hitting Vietnam; Extreme Damage in the Philippines

By: JeffMasters, 7:09 PM GMT on November 10, 2013

Typhoon Haiyan is closing in on the northern Vietnam coast near the Chinese border as a much-weakened Category 1 storm with 85 mph winds, after devastating the Philippines on Thursday and Friday as an extreme Category 5 storm with top winds of 195 mph. Satellite loops show that Haiyan no longer has a well-defined eye, but the typhoon still has a large area of intense thunderstorms which are bringing heavy rains of up to 1.5 inches per hour to Vietnam and Southeastern China. Haiyan will weaken and dissipate by Monday as it pushes inland over southern China, but the 8+ inches of rain that the storm will dump on Vietnam and Southeastern China will cause major flooding problems.

Haiyan is the third significant storm to hit Vietnam in the past six weeks. According to reliefweb.int, in the first two weeks of October, Central Vietnam was hit by two Category 1 storms, Typhoons Wutip and Nari, leaving behind significant damages in nine provinces. The total economic loss due to Nari was $71 million. Typhoon Wutip's damages were estimated at $663 million. According to EM-DAT, this makes Wutip the second most expensive natural disaster in Vietnamese history, behind the $785 million in damages caused by 2009's Typhoon Ketsana.


Figure 1. MODIS satellite image of Typhoon Haiyan taken at approximately 4:25 UTC November 10, 2013. At the time, Haiyan was a Category 1 storm with top winds of 90 mph. Image credit: NASA.

Extreme damage in the Philippines
With a preliminary death toll of 1,200, Haiyan already ranks as the 8th deadliest typhoon in Philippines history. The deadliest typhoon in Philippines history was Typhoon Thelma of 1991, which killed between 5101 - 8000 people, reports wunderground's weather historian Christopher C. Burt in his latest post on Philippines typhoon history. Haiyan will become the deadest typhoon in Philippines history if the estimates today of 10,000 dead hold up. Bloomberg Industries is estimating insured damages of $2 billion and total economic damages of $14 billion, making Haiyan the most expensive natural disaster in Philippines history. This is the third time in the past 12 months the Philippines have set a new record for their most expensive natural disaster in history. The record was initially set by Typhoon Bopha of December 2012, with $1.7 billion in damage; that record was beaten by the $2.2 billion in damage done by the August 2013 floods on Luzon caused by moisture associated with Typhoon Trami.


Figure 2. A Filipino boy carries bottled water amongst the damaged houses where a ship was washed ashore in Tacloban city, Leyte province, central Philippines on Sunday, Nov. 10, 2013. (AP Photo/Aaron Favila)

The greatest death toll from Haiyan is likely to be in the capital of Leyte, Tacloban (population 221,000), which received a direct hit from Haiyan's northern eyewall. A stark eyewitness account posted to Facebook of what Tacloban endured, by storm chaser Josh Morgerman of iCyclone.com:

"First off, Tacloban City is devastated. The city is a horrid landscape of smashed buildings and completely defoliated trees, with widespread looting and unclaimed bodies decaying in the open air. The typhoon moved fast and didn't last long--only a few hours--but it struck the city with absolutely terrifying ferocity. At the height of the storm, as the wind rose to a scream, as windows exploded and as our solid-concrete downtown hotel trembled from the impact of flying debris, as pictures blew off the walls and as children became hysterical, a tremendous storm surge swept the entire downtown. Waterfront blocks were reduced to heaps of rubble. In our hotel, trapped first-floor guests smashed the windows of their rooms to keep from drowning and screamed for help, and we had to drop our cameras and pull them out on mattresses and physically carry the elderly and disabled to the second floor. Mark's leg was ripped open by a piece of debris and he'll require surgery. The city has no communication with the outside world. The hospitals are overflowing with the critically injured. The surrounding communities are mowed down. After a bleak night in a hot, pitch-black, trashed hotel, James, Mark, and I managed to get out of the city on a military chopper and get to Cebu via a C-130--sitting next to corpses in body bags. Meteorologically, Super Typhoon HAIYAN was fascinating; from a human-interest standpoint, it was utterly ghastly. It's been difficult to process."


Video 1. Storm chasers James Reynolds, Josh Morgerman and Mark Thomas of iCyclone.com were in the capital of Leyte Province, Tacloban, which received a direct hit from Super Typhoon Haiyan. Video includes the remarkable winds and storm surge of Haiyan, and the rescue of injured people from flood waters.

Extreme damage near the initial landfall location
Rescuers have finally reached the south shore of Samar Island and the city of Guiuan (population 47,000), where Haiyan initially made landfall with winds estimated at 195 mph. Typhoon and hurricane maximum wind speed estimates are only valid for over water exposure, and winds over land are typically reduced by about 15%, due to friction. This would put Haiyan's winds at 165 mph over land areas on the south shore of Guiuan Island. This is equivalent to a high end EF-3 tornado, and damage photos from the town do show tornado-like damage--though much of the worst damage appears to be due to the storm surge. A new Doppler radar that was scheduled to go into operation in 2014 was blown off the tower it was installed on.


Figure 3. Col John Sanchez, Central Command, AFP took these photos from a PAF Nomad aircracft over Guiuan, E. Samar, Sunday morning from 1030H to 1045H: "Guiuan bore the brunt of Super Typhoon Yolanda at its first landfall Friday. One hundred percent of the structures either had their roofs blown away or sustained major damage. Nearly all coconut trees fell. We saw people in the streets, seemingly dazed. Trucks and cars were left in the streets where they were stopped in their tracks as Yolanda struck. We were probably the first outsiders to fly over the area since Friday and obviously, no relief goods have arrived there yet. It was almost lunchtime but there was no smoke from cooking fires. The 2.4 km runway is clear of debris and could still be used by C130 aircraft. Yolanda is probably worse than Pablo and the only reason why we have no reports of casualties up to now is that communications systems in Region 8 are down." Image credit: Col John Sanchez , Central Command, AFP.

Haiyan's place in history
Haiyan hit Guiuan, on the Philippine island of Samar, at 4:40 am local time November 8, 2013 (20:40 UTC November 7.) Three hours before landfall, the Joint Typhoon Warning Center (JTWC) assessed Haiyan’s sustained winds at 195 mph, gusting to 235 mph, making it the 4th strongest tropical cyclone in world history. Satellite loops show that Haiyan weakened only slightly, if at all, in the two hours after JTWC’s advisory, so the super typhoon likely made landfall with winds near 195 mph. The next JTWC intensity estimate, for 00Z UTC November 8, about three hours after landfall, put the top winds at 185 mph. Averaging together these estimates gives a strength of 190 mph an hour after landfall. Thus, Haiyan had winds of 190 - 195 mph at landfall, making it the strongest tropical cyclone on record to make landfall in world history. The previous record was held by the Atlantic's Hurricane Camille of 1969, which made landfall in Mississippi with 190 mph winds.

The Japan Meteorological Agency (JMA), which uses their own techniques to estimate typhoon strength via satellite imagery, put Haiyan's peak strength at 125 knots (145 mph), using a 10-minute averaging time for wind speeds. The Philippines weather agency (PAGASA) also uses a 10-minute averaging time for their typhoon wind advisories, and winds estimated by either JMA or PAGASA for Haiyan have appeared in the media, resulting in some confusion about what the typhoon's winds were at landfall. The averaging time used by JTWC and NHC is 1-minute, resulting in a higher wind estimate. To convert from 10-minute averaged winds to 1-minute average, one conversion factor that is commonly used is to multiply by 1.14--though lower conversion factors are sometimes used. Note that even after correcting for the difference between using 1-minute and 10-minute wind averaging times, the JMA wind estimates are well below what JTWC estimated; JMA consistently estimates weaker winds for high-end typhoons than JTWC. Since we have no actual measurements of the winds or pressure from Haiyan at landfall, we don't know which agency made a more accurate wind estimate.

With Angela Fritz' help, I've put together a list of most intense world tropical cyclones at landfall, using 1-minute averaging times. The list is unofficial and may have omissions; email me at jmasters@wunderground.com if you have suggestions for improvement:



Tropical disturbance 90W will bring more heavy rain to the Philippines
A tropical disturbance located east of the Philippines near 5°N 136°E, (Invest 90W), is steadily organizing, and has the potential to become a tropical depression by Monday. The disturbance has developed an elongated surface circulation and a respectable amount of heavy thunderstorm activity. Wind shear is low, but the disturbance is too close to the Equator intensify quickly, since the storm will not be able to leverage Earth's spin to get itself spinning. The disturbance has a high chance of development, according to Sunday's 17:30 UTC Western Pacific Tropical Weather Discussion by the Joint Typhoon Warning Center. A number of recent runs by the GFS model have predicted that the disturbance will organize into a tropical depression or weak tropical storm by Tuesday, when it will pass through the southern or central Philippines. I expect 90W will be organized enough to bring heavy rains of 2 - 4" to the area devastated by Super Typhoon Haiyan on Tuesday and Wednesday, and give a 70% chance it will be a tropical depression or weak tropical storm by Tuesday. The Japan Meteorological Agency is already classifying 90W as a tropical depression.

The Red Cross is appealing for donations.

Portlight disaster relief charity is reaching out to disability organizations in the Philippines to provide durable medical equipment. and welcomes donations.

Google Person Finder: Typhoon Yolanda - Google.org

Links
Wunderblogger Lee Grenci discusses mesovorticies in the eye of Haiyan in his latest post.
Wunderground's weather historian Christopher C. Burt reviews the Philippine's typhoon history.
The University of Wisconsin CIMSS Satellite Blog has a great collection of satellite images of Haiyan.
NOAA's Michael Folmer has a post showing the unusual burst of lightning that occurred at landfall in Haiyan.
Hurricanes and Climate Change: Huge Dangers, Huge Unknows, my August 2013 blog post.
Storm Chaser James Reynolds on Twitter, from Tacloban, Leyte.
Storm Chaser Jim Edds on Twitter, from Tacloban, Leyte.

Jeff Masters

Hurricane

Typhoon Haiyan Kills 1,200 in the Philippines, Heads for Vietnam

By: JeffMasters, 6:46 PM GMT on November 09, 2013

Typhoon Haiyan is headed across the South China Sea towards Vietnam as a much-weakened Category 3 storm with 115 mph winds after devastating the Philippines on Thursday and Friday as an extreme Category 5 storm with winds of 195 mph. With a preliminary death toll of 1,200, Haiyan already ranks as the 8th deadliest typhoon in Philippines history. Bloomberg Industries is estimating insured damages of $2 billion and total economic damages of $14 billion, making Haiyan the most expensive natural disaster in Philippines history. This is the third time in the past 12 months the Philippines have set a new record for their most expensive natural disaster in history. The record was initially set by Typhoon Bopha of December 2012, with $1.7 billion in damage; that record was beaten by the $2.2 billion in damage done by the August 2013 floods on Luzon caused by moisture associated with Typhoon Trami.


Figure 1. Typhoon Haiyan leaving the Philippines on November 9, 2013, as photographed by astronaut Karen Nyberg on the International Space Station.

Massive damage in the Philippines
It is still early in the rescue and recovery effort, and the death toll will undoubtedly rise significantly. Rescuers have not yet reached the south shore of Samar Island and the city of Guiuan (population 47,000), where Haiyan initially made landfall with winds estimated at 195 mph. Typhoon and hurricane maximum wind speed estimates are only valid for over water exposure, and winds over land are typically reduced by about 15%, due to friction. This would put Haiyan's winds at 165 mph over land areas on the south shore of Guiuan Island. This is equivalent to a high end EF-3 or low end EF-4 tornado, so the wind damage there must have been catastrophic--perhaps the greatest wind damage any place on Earth has endured from a tropical cyclone in the past century.


Figure 2. Damage from Super Typhoon Haiyan in Tacloban, Philippines on November 9, 2013. Image credit: NOEL CELIS/AFP/Getty Images.


Figure 3. Radar image of Super Typhoon Haiyan over Tacloban, on November 8, 2013. Tacloban was in the north (strongest) portion of Haiyan's eyewall, at a time when the typhoon's top sustained winds over water were estimated at 185 mph. Image credit: http://climatex.ph.

Haiyan's place in history
Haiyan hit Guiuan, on the Philippine island of Samar, at 4:40 am local time (20:40 UTC) November 8, 2013. Three hours before landfall, the Joint Typhoon Warning Center (JTWC) assessed Haiyan’s sustained winds at 195 mph, gusting to 235 mph, making it the 4th strongest tropical cyclone in world history. Satellite loops show that Haiyan weakened only slightly, if at all, in the two hours after JTWC’s advisory, so the super typhoon likely made landfall with winds near 195 mph. The next JTWC intensity estimate, for 00Z UTC November 8, about three hours after landfall, put the top winds at 185 mph. Averaging together these estimates gives a strength of 190 mph an hour after landfall. Thus, Haiyan had winds of 190 - 195 mph at landfall, making it the strongest tropical cyclone on record to make landfall in world history. The previous record was held by the Atlantic's Hurricane Camille of 1969, which made landfall in Mississippi with 190 mph winds.


Figure 4. Predicted rainfall from the 06Z November 9, 2013 run of the HWRF model, for the 66-hour period ending at 00Z November 12, 2013. A 100-mile wide swath of 8 - 16 inches of rain (medium dark red colors) is predicted to affect northern Vietnam. Rains of this magnitude are likely to cause a top-five most expensive natural disaster in Vietnamese history. Image credit: NOAA/NCEP/EMC.

Haiyan an extremely dangerous storm for Vietnam
Satellite loops show that Haiyan no longer has a well-defined eye, but the typhoon still has a huge area of intense thunderstorms which are already bringing heavy rains to Vietnam. Haiyan will continue to weaken until landfall, due to colder waters and higher wind shear, and will likely be a large and very wet tropical storm when it makes landfall in Vietnam on Sunday. Haiyan is expected to begin recurving to the northwest as it makes landfall, which means that a long 100+ mile stretch of the Vietnam coast will be receiving the punishing winds and peak storm surge of the strong northern portion of the storm. With part of its circulation still over water, Haiyan will be able to pull in a huge amount of moisture that will create prodigious rains over Vietnam. With the latest forecast track now expected take Haiyan farther north before landfall than previously expected, the extreme rainfall danger for Laos has diminished, but I expect that the 8+ inches of rain that the storm will dump on Vietnam will make it a top-five most expensive natural disaster in their history.

According to reliefweb.int, in the first two weeks of October, Central Vietnam was hit by two Category 1 storms, Typhoons Wutip and Nari, leaving behind significant damages in nine provinces. The total economic loss due to Nari was $71 million. Typhoon Wutip's damages were estimated at $663 million. According to EM-DAT, this makes Wutip the second most expensive natural disaster in Vietnamese history, behind the $785 million in damages caused by 2009's Typhoon Ketsana, which also killed 192 people in Vietnam.


Video 1. Storm chasers James Reynolds, Josh Morgerman and Mark Thomas of iCyclone.com were in the capital of Leyte Province, Tacloban, which received a direct hit from Super Typhoon Haiyan. Video includes the remarkable winds and storm surge of Haiyan, and the rescue of injured people from flood waters.

More heavy rain coming to the Philippines
A tropical disturbance located east of the Philippines near 3°N 141°E, (Invest 90W), has developed a modest amount of spin and heavy thunderstorm activity as it heads west towards the Philippines. With moderate wind shear and a location too close to the Equator to leverage Earth's spin, the disturbance will be slow to develop, according to the latest Western Pacific Tropical Weather Discussion by the Joint Typhoon Warning Center. The GFS model has been predicting for several days now that this disturbance will organize into a tropical depression by Monday and pass through the southern or central Philippines on Tuesday as a tropical storm. However, the latest 12Z run of the model no longer shows development, and keeps 90W as a tropical disturbance as it passes through the Philippines on Tuesday and Wednesday. I expect 90W will be organized enough to bring heavy rains of 2 - 4" to the area devastated by Super Typhoon Haiyan.

The Red Cross is appealing for donations.

Portlight disaster relief charity is reaching out to disability organizations in the Philippines to provide durable medical equipment. and welcomes donations.

New "Tipping Points" episode, "Africa Alarmed", airs Saturday at 9 pm EDT/8 pm CDT
“Tipping Points”, a landmark 6-part climate change TV series that began airing in October on The Weather Channel, airs for the fourth time on Saturday night, November 9, at 9 pm EDT. The new episode, "Africa Alarmed", goes on an expedition from the far north of the Sahara to the far south of the continent, in Cape Town, to explore the climate changes affecting Africa’s vital weather systems. The series is hosted by polar explorer and climate journalist Bernice Notenboom, the first woman to perform the remarkable triple feat of climbing Mt. Everest and walking to the North and South Poles. In each episode, Notenboom heads off to a far corner of the world to find scientists in the field undertaking vital climate research to try to understand how the climate system is changing and how long we have to make significant changes before we reach a tipping point--a point of no return when our climate system will be changed irreversibly.


Figure 5. "Tipping Points" host Bernice Notenboom visits the Gobabeb Research and Training Center in Africa's Namib Desert.

Jeff Masters

Hurricane

Super Typhoon Haiyan Finishes Pounding the Philippines, Headed for Vietnam

By: JeffMasters, 3:50 PM GMT on November 08, 2013

After spending 48 hours at Category 5 strength, the strongest landfalling tropical cyclone in world history, Super Typhoon Haiyan, has finally weakened to a Category 4 storm. With top sustained winds of 155 mph, Haiyan is still an incredibly powerful super typhoon, but has now finished its rampage through the Central Philippine Islands, and is headed across the South China Sea towards Vietnam. Satellite loops show that Haiyan no longer has a well-defined eye, but the typhoon still has a huge area of intense thunderstorms which are bringing heavy rains to the Central Philippines. I've never witnessed a Category 5 storm that made landfall and stayed at Category 5 strength after spending so many hours over land, and there are very few storms that have stayed at Category 5 strength for so long.


Figure 1. Super Typhoon Haiyan approaching the Philippines, as seen by the Japan Meteorological Agency's MTSAT at 0630Z on November 7, 2013. At the time, Haiyan had maximum sustained winds of 175 mph. Image credit: NOAA Environmental Visualization Laboratory.

Haiyan's place in history
Haiyan hit Guiuan, on the Philippine island of Samar, at 4:40 am local time (20:40 UTC) November 8, 2013. Three hours before landfall, the Joint Typhoon Warning Center (JTWC) assessed Haiyan’s sustained winds at 195 mph, gusting to 235 mph, making it the 4th strongest tropical cyclone in world history. Satellite loops show that Haiyan weakened only slightly, if at all, in the two hours after JTWC’s advisory, so the super typhoon likely made landfall with winds near 195 mph. The next JTWC intensity estimate, for 00Z UTC November 8, about three hours after landfall, put the top winds at 185 mph. Averaging together these estimates gives a strength of 190 mph an hour after landfall. Thus, Haiyan had winds of 190 - 195 mph at landfall, making it the strongest tropical cyclone on record to make landfall in world history. The previous record was held by the Atlantic's Hurricane Camille of 1969, which made landfall in Mississippi with 190 mph winds.

According to the official "best track" records from the Joint Typhoon Warning Center, here are the strongest tropical cyclones in world history:

Super Typhoon Nancy (1961), 215 mph winds, 882 mb. Made landfall as a Cat 2 in Japan, killing 191 people.
Super Typhoon Violet (1961), 205 mph winds, 886 mb pressure. Made landfall in Japan as a tropical storm, killing 2 people.
Super Typhoon Ida (1958), 200 mph winds, 877 mb pressure. Made landfall as a Cat 1 in Japan, killing 1269 people.
Super Typhoon Haiyan (2013), 195 mph winds, 895 mb pressure. Made landfall in the Philippines at peak strength.
Super Typhoon Kit (1966), 195 mph winds, 880 mb. Did not make landfall.
Super Typhoon Sally (1964), 195 mph winds, 895 mb. Made landfall as a Cat 4 in the Philippines.

However, it is now recognized (Black 1992) that the maximum sustained winds estimated for typhoons during the 1940s to 1960s were too strong. The strongest reliably measured tropical cyclones were all 5 mph weaker than Haiyan, with 190 mph winds—the Western Pacific's Super Typhoon Tip of 1979, the Atlantic's Hurricane Camille of 1969, and the Atlantic's Hurricane Allen of 1980. All three of these storms had a hurricane hunter aircraft inside of them to measure their top winds. Haiyan's winds were estimated using only satellite images, making its intensity estimate of lower confidence. We don't have any measurements of Haiyan's central pressure, but it may be close to the all-time record of 870 mb set by Super Typhoon Tip. The Japan Meteorological Agency estimated Haiyan's central pressure at 895 mb at 18 UTC (1 pm EST) November 7, 2013. This would make Haiyan the 12th strongest tropical cyclone on record globally, as far as lowest pressure goes.


Figure 2. Damage from Super Typhoon Haiyan in Legazpi city, Albay province, Nov. 8, 2013, about 325 miles south of Manila, Philippines. (Twitter/Ritchel M. Deleon)

Massive damage in the Philippines
Wind damage on the south shore of Samar Island in Guiuan (population 47,000) must have been catastrophic, perhaps the greatest wind damage any place on Earth has endured from a tropical cyclone in the past century. A massive storm surge must have also caused great destruction along a 20-mile swath to the north of where the eye hit, where Project NOAH was predicting a 17’ (5.3 meter) storm tide. Wind and storm surge damage were heavy in Tacloban, population 221,000, the capital of the province of Leyte, according to preliminary media reports. Much of Tacloban is at elevations less than ten feet, and several videos posted on YouTube showed a storm surge of at least ten feet moving through the city. The northern (strong) part of Haiyan’s eyewall made a direct hit on the city. Storm Chaser Jim Edds was in Tacloban, and reported that at least ten crewed boats were in the harbor, attempting to ride out the storm. Haiyan’s winds, rains, and storm surge have caused widespread devastation throughout the Central Philippines, though we do not yet have reports from the worst-hit portions of the disaster zone, including the south shore of Samar Island. Fortunately, the storm’s fast forward speed of 25 mph cut down the amount of rain the storm dumped, compared to typical typhoons that affect the Philippines. Hopefully, this will keep the death toll due to flash flooding relatively low. Flash floods are usually the biggest killer in Philippine typhoons.


Figure 3. Predicted rainfall from the 06Z November 8, 2013 run of the HWRF model, for the 96-hour period ending at 06Z November 12, 2013. A 100-mile wide swath of 8 - 16 inches of rain (medium dark red colors) as well as a 30-mile wide swath of 16 - 24" (dark red colors) is predicted to affect Vietnam and Laos. Rains of this magnitude are likely to cause a top-five most expensive natural disaster in both nations. Image credit: NOAA/NCEP/EMC.

Haiyan an extremely dangerous storm for Vietnam and Laos
Haiyan will steadily decay over the next two days, due to colder waters and higher wind shear. However, it will still likely be a formidable Category 1 or 2 typhoon when it makes landfall in Vietnam near 06 UTC Sunday. Haiyan is expected to begin recurving to the northwest as it makes landfall, which means that a long 100+ mile stretch of the Vietnam coast will receiving the punishing winds and peak storm surge of the strong northern portion of the typhoon. With part of its circulation still over water, Haiyan will be able to pull in a huge amount of moisture that will create prodigious rains over Vietnam and Laos. I expect that the 12+ inches of rain that the storm will dump on those nations will make it a top-five most expensive natural disaster in their history.

Links
Visible satellite landfall loop from the Korean COMS-1 satellite, courtesy of Scott Bachmeier of the University of Wisconsin CIMSS group.
Damage videos from Tacloban from Marcjan Maloon
Twitter updates from Japan meteorologist Robert Speta.


Video 1. Damaging winds and a potent storm surge from Super Typhoon Haiyan are captured in this video from the capital of Leyte Province, Tacloban, which received a direct hit from Haiyan. Thanks to wunderground member GatorWX for posting this in my blog comments.

Jeff Masters

Hurricane

Super Typhoon Haiyan: Strongest Landfalling Tropical Cyclone on Record

By: JeffMasters, 10:58 PM GMT on November 07, 2013

Super Typhoon Haiyan has made landfall. According to PAGASA, Haiyan came ashore at 4:40 am local time (20:40 UTC) November 7, 2013 near Guiuan, on the Philippine island of Samar. Fourty minutes before landfall, Guiuan reported sustained 10-minute average winds of 96 mph, with a pressure of 977 mb. Contact has since been lost with the city. Three hours before landfall, the Joint Typhoon Warning Center (JTWC) assessed Haiyan’s sustained winds at 195 mph, gusting to 235 mph, making it the 4th strongest tropical cyclone in world history. Satellite loops show that Haiyan weakened only slightly, if at all, in the two hours after JTWC’s advisory, so the super typhoon likely made landfall with winds near 195 mph. The next JTWC intensity estimate, for 00Z UTC November 8, about three hours after landfall, put the top winds at 185 mph. Averaging together these estimates gives a strength of 190 mph an hour after landfall. Thus, Haiyan had winds of 190 - 195 mph at landfall, making it the strongest tropical cyclone on record to make landfall in world history. The previous record was held by the Atlantic's Hurricane Camille of 1969, which made landfall in Mississippi with 190 mph winds.


Figure 3. Radar image of Super Typhoon Haiyan shortly after landfall, at 6:14 am local time on November 8, 2013. Image credit: http://climatex.ph.

Officially, here are the strongest tropical cyclones in world history:

Super Typhoon Nancy (1961), 215 mph winds, 882 mb. Made landfall as a Cat 2 in Japan, killing 191 people.
Super Typhoon Violet (1961), 205 mph winds, 886 mb pressure. Made landfall in Japan as a tropical storm, killing 2 people.
Super Typhoon Ida (1958), 200 mph winds, 877 mb pressure. Made landfall as a Cat 1 in Japan, killing 1269 people.
Super Typhoon Haiyan (2013), 195 mph winds, 895 mb pressure. Made landfall in the Philippines at peak strength.
Super Typhoon Kit (1966), 195 mph winds, 880 mb. Did not make landfall.
Super Typhoon Sally (1964), 195 mph winds, 895 mb. Made landfall as a Cat 4 in the Philippines.

However, it is now recognized (Black 1992) that the maximum sustained winds estimated for typhoons during the 1940s to 1960s were too strong. The strongest reliably measured tropical cyclones were all 5 mph weaker than Haiyan, with 190 mph winds—the Western Pacific's Super Typhoon Tip of 1979, the Atlantic's Hurricane Camille of 1969, and the Atlantic's Hurricane Allen of 1980. All three of these storms had a hurricane hunter aircraft inside of them to measure their top winds. Haiyan's winds were estimated using only satellite images, making its intensity estimate of lower confidence. We don't have any measurements of Haiyan's central pressure, but it may be close to the all-time record of 870 mb set by Super Typhoon Tip. The Japan Meteorological Agency estimated Haiyan's central pressure at 895 mb at 18 UTC (1 pm EST) November 7, 2013. This would make Haiyan the 12th strongest tropical cyclone on record globally, as far as lowest pressure goes.


Extreme damage likely in the Philippines
Wind damage in Guiuan (population 47,000) must have been catastrophic, perhaps the greatest wind damage any city on Earth has endured from a tropical cyclone in the past century. A massive storm surge must have also caused great destruction along a 20-mile swath to the north of where the eye hit, where Project NOAH was predicting a 17’ (5.3 meter) storm tide. Wind damage will also be extreme in Tacloban, population 221,000, the capital of the province of Leyte. Much of Tacloban is at elevations less than ten feet, and the most recent storm surge forecast made by the Philippines' Project NOAH calls for a storm tide (the combined height of the surge plus the tide) of 12’ (3.6 meters) in Tacloban. The northern (strong) part of Haiyan’s eyewall is now battering the southern part of the city. Haiyan’s winds, rains, and storm surge will cause widespread devastation throughout the Central Philippines during the day, though the storm’s fast forward speed of 25 mph will cut down on the total rainfall amounts, compared to typical typhoons that affect the Philippines. Hopefully, this will substantially recede the death toll due to flash flooding, which is usually the biggest killer in Philippine typhoons. Once Haiyan exits into the South China Sea, it will steadily decay, due to colder waters and higher wind shear. However, it will still be a formidable Category 1 or 2 typhoon when it hits Vietnam and Laos, and I expect that the 12+ inches of rain that the storm will dump on those nations will make it a top-five most expensive natural disaster in their history. Early on Thursday, Haiyan hit the island of Kayangel, 24 kilometres north of Palau's capital, Koror. Damage was heavy, with many homes damaged or destroyed, but there were no injuries among the island’s 69 inhabitants.

Links
Visible satellite landfall loop from the Korean COMS-1 satellite, courtesy of Scott Bachmeier of the University of Wisconsin CIMSS group.
Impressive videos from Tacloban from Marcjan Maloon
Twitter updates from Japan meteorologist Robert Speta.
Storm Chaser James Reynolds on Twitter, from Tacloban, Leyte.
Storm Chaser Jim Edds on Twitter, from Tacloban, Leyte.
Webcam in Malay, Philippines
Webcam in Boracay, Philippines

Jeff Masters

Hurricane

Super Typhoon Haiyan Closes in on the Philippines With 190 mph Sustained Winds

By: JeffMasters, 4:41 PM GMT on November 07, 2013

Super Typhoon Haiyan is one of the most intense tropical cyclones in world history, with sustained winds an incredible 190 mph, gusting to 230 mph, said the Joint Typhoon Warning Center in their 15 UTC (10 am EST) November 7, 2013 advisory. Officially, the strongest tropical cyclone in world history was Super Typhoon Nancy of 1961, with sustained winds of 215 mph. However, it is now recognized (Black 1992) that the maximum sustained winds estimated for typhoons during the 1940s to 1960s were too strong. Since 1969, only three tropical cyclones have equaled Haiyan's 190 mph sustained winds--the Western Pacific's Super Typhoon Tip of 1979, the Atlantic's Hurricane Camille of 1969, and the Atlantic's Hurricane Allen of 1980. All three of these storms had a hurricane hunter aircraft inside of them to measure their top winds, but Haiyan's winds were estimated using only satellite images, making its intensity estimate of lower confidence. Some interpretations of satellite intensity estimates suggest that there may have been two super typhoons stronger than Tip--Super Typhoon Gay of 1992, and Super Typhoon Angela of 1995. We don't have any measurements of Haiyan's central pressure, but it may be close to the all-time record of 870 mb set by Super Typhoon Tip. The Japan Meteorological Agency estimated Haiyan's central pressure at 895 mb at 12 UTC (7 am EST) November 7, 2013. Haiyan has the most spectacular appearance I've ever seen on satellite loops, with a prominent eye surrounded by a huge, impenetrable-looking mass of intense eyewall thunderstorms with tops that reach into the lower stratosphere. With landfall expected to occur by 21 UTC (4 pm EST) on Thursday, Haiyan doesn't have time to weaken much before landfall, and will likely hit the Philippines at Category 5 strength.


Figure 1. MODIS satellite image of Super Typhoon Haiyan taken at 4:25 UTC November 7, 2013. At the time, Haiyan was a Category 5 storm with top winds of 175 mph. The Philippines are visible at the left of the image, and the Caroline Islands at the lower right. Image credit: NASA.

Haiyan will be the third Category 5 typhoon to make landfall in the Philippines since 2010. In 2010, Super Typhoon Megi peaked at 180 mph winds just east of Luzon Island in the Philippines, and made landfall in the Philippines as a Category 5 storm. Megi's landfall was proof that the Philippines can withstand a strike by a Category 5 storm without a catastrophe resulting, as Megi killed only 35 people, and did $276 million in damage. However, the last Category 5 storm to hit the Philippines--Super Typhoon Bopha, which hit the southern Philippine island of Mindanao on December 3, 2012--did cause a catastrophe. The typhoon left 1901 people dead, mostly on the island of Mindanao, making Bopha the 2nd deadliest typhoon in Philippine history. With damages estimated at $1.7 billion, Bopha was the costliest natural disaster in Philippines history at the time.


Figure 2. Super Typhoon Megi as seen by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite at 10:35 a.m. Philippine Time (02:35 UTC) on October 18, 2010. Megi was bearing down on Luzon Island in the Philippines as a Category 5 storm with 170 mph winds. Megi killed 35 and did $276 million in damage, making it the 6th most expensive typhoon in Philippines history. Image credit: NASA Earth Observatory.

Haiyan's deadliest danger: heavy rains, high winds
The deadliest threat from Philippine typhoons is usually heavy rains, since the islands are very mountainous, leading to very high rainfall amounts capable of causing dangerous flash floods and mudslides. Deforestation of the mountainous slopes has contributed to this problem in recent decades. The latest rainfall forecast from the 06Z November 7, 2013 run of the HWRF model is not encouraging. A 50-mile wide swath of 8+ inches of rain is predicted to cross the Central Philippines. The soils are already very wet from the heavy rains that Tropical Depression 30 dumped over the region on Monday, so the rains from Haiyan will runoff quickly and create life-threatening flooding. Haiyan's winds are also a huge concern, particularly in Tacloban, population 221,000, the capital of the province of Leyte. Tacloban will likely receive a direct hit, and I expect the sustained winds from Haiyan will be at Category 4 strength in the city.


Figure 3. Predicted rainfall from the 06Z November 7, 2013 run of the HWRF model, for the 108-hour period ending at 18Z November 11, 2013. A 50-mile wide swath of 8+ inches of rain (medium dark red colors) is predicted to cross the Central Philippines and Northern Vietnam. This is likely an underestimate of the rains, since Haiyan is now stronger than what the HWRF model was predicting at 06Z. Image credit: NOAA/NCEP/EMC.

Haiyan a serious storm surge threat
Haiyan will cause much higher storm surge damage than is typical for a Philippines typhoon. A worst-case scenario now appears unlikely, as the current forecast track will keep the storm surge from building into the funnel-shaped Leyte Gulf, which comes to a point in Tacloban, population 221,000, the capital of the province of Leyte. Much of Tacloban is at elevations less than ten feet, and storm surge forecasts made earlier today by the Philippines' Project NOAH were calling for a storm tide (the combined height of the surge plus the tide) of 15' (4.5 meters) in Tacloban. With Haiyan now expected to push the waters out of Leyte Gulf upon approach, the storm tide will likely not get that high in Tacloban. The greatest storm tide will occur to the east of Tacloban on the east shore of Samar Island, where a massive 17' (5.3 meter) storm tide was predicted by Project NOAH. Many locations in the Central Philippines are expected to see storm tides in excess of 8' (2.5 meters), after Haiyan crosses Leyte and Samar Islands. To give you some idea of the size and power of Haiyan, a storm tide of 4.5' (1.4 meters) is predicted in the capital of Manila, even though the typhoon is expected to pass 180 miles to the south of the city. An experimental storm surge forecast from the European Commission's Joint Research Centre HyFlux2 model calls for a peak storm surge of 7.5 feet (2.3 meters) from Haiyan. This model has not been verified for the Philippines, and I expect the storm surges from a 190 mph Category 5 typhoon will be more in line with what Project NOAH is predicting. Here are the storm tide forecasts, which are updated every six hours on the the Philippines' Project NOAH website:




Figure 4. Elevation map of Leyte Island (left) and Samar Island (top) in the Philippines. Much of the capital of Leyte, Tacloban, is at an elevation less than 4 meters (13'), red to dark red colors. The predicted path of Haiyan’s eye in the 15 UTC November 7, 2013 Joint Typhoon Warning Center advisory is shown. Image credit: Globalwarmingart.com.

Haiyan the fifth named storm to hit the Philippines in 2013
Haiyan will be the fourth typhoon and fifth named storm to hit the Philippines this year. The others were:

Tropical Storm Rumbia, which hit the island of Samar on June 29 as a tropical storm, killing six.
Typhoon Nari, which hit Luzon on October 11 as a Category 3 typhoon with 115 mph winds, killing five.
Typhoon Utor, which hit Luzon on August 12 as a Category 4 typhoon with 140 mph winds, killing fourteen and causing $25 million in damage.
Typhoon Krosa, which hit northern Luzon on October 31 as a Category 2 typhoon with 105 mph winds, killing five and doing $5 million in damage.

Links
Storm Chaser James Reynolds on Twitter, from Tacloban, Leyte.
Storm Chaser Jim Edds on Twitter, from Tacloban, Leyte.
Webcam in Malay, Philippines
Webcam in Boracay, Philippines

Jeff Masters

Hurricane

Category 5 Super Typhoon Haiyan Headed Towards the Philippines

By: JeffMasters, 3:05 PM GMT on November 06, 2013

Evacuations are underway in the Philippines Islands as extremely dangerous Category 5 Super Typhoon Haiyan heads west-northwest at 20 mph towards the islands. Haiyan, which is the Chinese word for a petrel seabird, is referred to as "Yolanda" in the Philippines, and became a Category 5 storm with 160 mph winds at 12 UTC (7 am EDT) Wednesday. Haiyan became a Cat 5 at an unusually low latitude (7.9°N), but this is not a record. The most southerly Cat 5 on record was Super Typhoon Louise of 1964 (7.3°N), followed by 2012's Super Typhoon Bopha (7.4°N.) Haiyan is the fourth Category 5 storm in the Western Pacific and fifth on Earth so far in 2013. This is the highest number of Cat 5s since 2009, which had four Cat 5s in the Western Pacific and one in the Eastern Pacific. Since 2000, Earth has averaged 4.4 of these mightiest of tropical cyclones per year. The record for Cat 5s in a year is twelve, set in 1997, when an astonishing ten Cat 5s occurred in the Western Pacific. The Atlantic has not had a Category 5 storm since Hurricane Felix of 2007, making the past six years the longest stretch without a Cat 5 since 1981 - 1987.


Figure 1. Visible satellite image of Haiyan taken at 1:57 UTC November 6, 2013. The islands at the left are part of the Caroline Islands, which recorded sustained winds of 37 mph, gusting to 47 mph, at 15 UTC November 7, 2013. Image credit: University of Wisconsin CIMSS.

Satellite loops show that Haiyan is a spectacular typhoon with a tiny pinhole eye just 9 miles in diameter. A buoy (station 52087) reported a pressure of 956 mb and sustained WNW winds of 67 mph at 1000 UTC (5 am EDT) Tuesday morning in the southern eyewall of Haiyan. With warm waters that extend to great depth, low wind shear, and excellent upper-level outflow, Haiyan will likely stay at Category 4 or 5 strength until landfall occurs between 03 - 06 UTC Friday in the central Philippine islands of Samar or Leyte. The only brake on Haiyan's strength over the next day might be an eyewall replacement cycle, which will be capable of causing a temporary weakening of perhaps 20 mph in the storm's winds.


Figure 2. Predicted rainfall from the 06Z November 6, 2013 run of the HWRF model, for the 126-hour period ending at 12Z November 11, 2013. A 100-mile wide swath of 8+ inches of rain (medium dark red colors) is predicted to cross the Central Philippines and Northern Vietnam. Image credit: NOAA/NCEP/EMC.

Haiyan a major storm surge threat
The storm surge potential for Haiyan is very concerning, if the typhoon maintains its current forecast track and makes landfall on Leyte Island. This track would push a dangerous storm surge into the funnel-shaped Leyte Gulf, which comes to a point in Tacloban, population 221,000, the capital of the province of Leyte. Much of Tacloban is at elevations less than ten feet, and the experimental storm surge forecasts from the European Commission's Joint Research Centre HyFlux2 model made on November 5 and November 6 have called for a storm surge of 5 - 10 feet (1.6 - 2.9 meters) to hit Tacloban. This model has not been verified for the Philippines, and it is not unreasonable to speculate that the storm surge could be higher along a 20-mile swath of the coast to the north of where the eye hits, if it indeed comes ashore in Leyte. If the eye strikes farther north on Samar Island, this would not generate as high of a storm surge, since there is no triangular-shaped bay there to funnel the waters to a peak. Storm surge forecasts made by the Philippines' Project NOAH at 00 UTC November 6, 2013, are calling for no more than 2 meters (6.6 feet) of surge throughout the Philippines from Haiyan.


Figure 3. Elevation map of Leyte Island (left) and Samar Island (top) in the Philippines. Much of the capital of Leyte, Tacloban, is at an elevation less than 4 meters (13'), red to dark red colors. The predicted path of Haiyan’s eye in the 21 UTC November 6, 2013 Joint Typhoon Warning Center advisory is shown. Image credit: Globalwarmingart.com.

Haiyan the fifth named storm to hit the Philippines in 2013
Haiyan will be the fourth typhoon and fifth named storm to hit the Philippines this year. The others were:

Tropical Storm Rumbia, which hit the island of Samar on June 29 as a tropical storm, killing six.
Typhoon Nari, which hit Luzon on October 11 as a Category 3 typhoon with 115 mph winds, killing five.
Typhoon Utor, which hit Luzon on August 12 as a Category 4 typhoon with 140 mph winds, killing fourteen and causing $25 million in damage.
Typhoon Krosa, which hit northern Luzon on October 31 as a Category 2 typhoon with 105 mph winds, killing five and doing $5 million in damage.

The Philippines lie in the most tropical cyclone-prone waters on Earth, and rarely escape a year without experiencing a devastating typhoon. Usually, these storms impact the northern Philippine island of Luzon, but last year, Earth's deadliest weather disaster of 2012 occurred on the southern Philippine island of Mindanao, where Super Typhoon Bopha struck as a Category 5 super typhoon with winds of 160 mph (260 km/h), on December 3. Bopha made two additional landfalls in the Philippines, on central Visayas and on Palawan, on December 4. The typhoon left 1901 people dead, mostly on the island of Mindanao, making Bopha the 2nd deadliest typhoon in Philippine history. With damages estimated at $1.7 billion, Bopha was the costliest natural disaster in Philippines history. However, that mark was eclipsed just over four months ago, when torrential rains in the wake of Typhoon Trami inundated the capital of Manila and large areas of Luzon, killing 27 people and causing damages estimated at $2.2 billion by Aon Benfield.


Figure 4. Torrential rains, due, in part, to moisture from Typhoon Trami, fell in the Philippines August 18 - 21, 2013, causing massive flooding on Luzon Island that cost $2.2 billion. Twenty-seven people were killed, and 60% of metro Manila was under water at the peak of the flood. According to EM-DAT, the International Disaster Database, this flood would be the most expensive natural disaster in Philippine history. In this photo, pedicabs and makeshift rafts ferry office workers and pedestrians through flood waters that submerged parts of the financial district of Makati on August 20, 2013 in Makati City south of Manila, Philippines. Image credit: Dondi Tawatao/Getty Images)


Figure 5. Super Typhoon Bopha as seen from the International Space Station on December 2, 2012. At the time, Bopha had top sustained winds of 150 - 155 mph. Image credit: NASA.

Tropical Depression 30 a heavy rainfall threat for Southeast Asia
Tropical Depression 30 is making landfall over southern Vietnam, and will bring heavy rains of 8+ inches to portions of Vietnam, Cambodia, Laos, and Thailand over the next few days. The storm is expected to dissipate over Southeast Asia by Thursday.

Jeff Masters

Hurricane

Dangerous Category 2 Typhoon Haiyan Headed For the Philippines

By: JeffMasters, 3:14 PM GMT on November 05, 2013

Category 2 Typhoon Haiyan is rapidly intensifying as it steams west-northwest at 17 mph towards the Philippine Islands. Satellite loops show that Haiyan is a large and steadily organizing typhoon, with plenty of intense thunderstorms that are developing very cold cloud tops as they push high into the atmosphere. With warm waters that extend to great depth, low wind shear, and excellent upper-level outflow, there is nothing to keep Haiyan from growing into a 150 mph super typhoon by Thursday, and it may have a chance at becoming Earth's fifth Category 5 storm of 2013. Both the GFS and European models predict that Haiyan will hit the central Philippines between 3 - 6 UTC on Friday, and Haiyan will likely be the most dangerous tropical cyclone to affect the Philippines this year. This is particularly true since Tropical Depression Thirty dumped heavy rains over the central Philippines Monday, which helped saturate the soils. This morning's 06Z run of the HWRF model (Figure 2) predicted that Haiyan would hit the Philippines as a Category 3 storm, bringing a 200-mile wide swath of 4 - 8 inches of rain.


Figure 1. Visible satellite image of Haiyan taken just before sunset at 6:57 UTC November 5, 2013. Image credit: NOAA.


Figure 2. Predicted rainfall from the 06Z November 5, 2013 run of the HWRF model, for the 126-hour period ending at 12Z November 10, 2013. A 30-mile wide swath of 8+ inches of rain (medium dark red colors) is predicted to cross the Central Philippines, with a 200-mile wide swath of the islands receiving 4 - 8" (red colors.) Image credit: NOAA/NCEP/EMC.

Tropical Storm 30 a heavy rainfall threat for Southeast Asia
Tropical Storm 30 will hit southern Vietnam near 12 UTC on Wednesday, and bring heavy rains of 8+ inches to portions of Vietnam, Cambodia, Laos, and Thailand over the next few days. By Friday, the storm will emerge in the North Indian Ocean, where it will likely regenerate and potentially threaten Myanmar, India, or Bangladesh early next week.

Jeff Masters

Hurricane

Tropical Storm Sonia Hits Mexico; Eastern Pacific Hurricane Season Likely Over

By: JeffMasters, 2:50 PM GMT on November 04, 2013

In the Eastern Pacific, Tropical Storm Sonia, the eighteenth named storm of the 2013 Eastern Pacific hurricane season, made landfall near midnight EST on Sunday near El Dorado, Mexico, as a minimal tropical storm with 40 mph winds. Heavy rains of 3 - 6 inches are expected in Mainland Mexico along the path of Sonia on Monday, potentially triggering flash floods and mudslides. Moisture from Sonia is being drawn to the northeast, where it will contribute to rains over the Central U.S. later in the week. There are currently no threat areas to discuss in the Eastern Pacific, and the GFS and European models are not predicting development of anything over the coming seven days. The last named storm of the Eastern Pacific hurricane season typically forms on November 5, so there is a good chance that Sonia will be the last storm of the year. There were no November Eastern Pacific named storms in 2012, but 2011 featured the 2nd strongest storm of the entire Eastern Pacific hurricane season in November, Category 4 Hurricane Kenneth (145 mph winds.)


Figure 1. MODIS satellite image of Tropical Storm Sonia, taken at 18:10 UTC on November 3, 2013. At the time, Sonia had top winds of about 45 mph. Image credit: NASA.

The 2013 Eastern Pacific hurricane season in perspective
Sonia's formation brings the 2013 Eastern Pacific hurricane season numbers to 18 named storms, 7 hurricanes, and 1 major hurricane. The 1981 - 2010 averages for the Eastern Pacific hurricane season are 15 named storms, 8 hurricanes, and 4 major hurricanes. Due to the lack of major hurricanes, the Accumulated Cyclone Energy (ACE) has been just 51% of average so far in 2013. NOAA's pre-season prediction for the Eastern Pacific hurricane season, issued on May 23, was not far from the mark. It called for a below-average season, with 11 - 16 named storms, 5 - 8 hurricanes, 1 - 4 major hurricanes, and an ACE index 60% - 105% of the median. The mid-point of these ranges gives us a forecast for 13.5 named storms, 6.5 hurricanes, and 2.5 major hurricanes, with an ACE index 82% of average.

While the raw numbers show a quiet Eastern Pacific hurricane season, one bad storm--Hurricane Manuel--made the 2013 season one of the worst in Mexico's history. Manuel made landfall on September 15 near Manzanillo as a tropical storm with 70 mph winds, and brought devastating flooding to the coast near Acapulco. Manuel was the most expensive Eastern Pacific tropical cyclone in history, with damage estimated at $4.2 billion. The 169 people it killed made it the 7th deadliest Eastern Pacific tropical cyclone on record. Only three Eastern Pacific hurricanes have had their names retired--Hurricane Ismael of 1995, Hurricane Pauline of 1997, and Hurricane Kenna of 2002. Manuel is likely to become the fourth retired name on the list.

More trouble in the Western Pacific
Tropical cyclone activity in the Western Pacific over the past month has been very high, with seven typhoons in the month of October alone. According to records at the Joint Typhoon Warning Center (JTWC), this would appear to be a new record for the number of typhoons in any October, breaking the previous record of six typhoons during October 1989 (thanks go to typhoon expert Mark Lander for this stat.) The latest system of concern is Tropical Storm Haiyan, which is gathering strength over the warm tropical waters east of the Philippines. Haiyan's formation brings the tally of named storms in the Western Pacific in 2013 to 28, making it the busiest season in that ocean basin since the 32 named storms of 2004. Satellite loops show that Haiyan is a large tropical storm with plenty of intense thunderstorms that are steadily growing more organized. Haiyan is expected to take advantage of warm waters and low wind shear and intensify into a major Category 4 typhoon by Thursday. Both the GFS and European models predict that Haiyan will pass through the central Philippines near 6 UTC on Friday. If this prediction holds true, Haiyan could be the most dangerous tropical cyclone to affect the Philippines this year--particularly since Tropical Depression Thirty is dumping heavy rains of up to one inch per hour over the central Philippines today, which will saturate the soil and make extreme flooding more likely late this week when Haiyan arrives.

Quiet in the Atlantic
An area of low pressure over the Central Caribbean is bringing disorganized heavy rain showers to the region. Wind shear is a high 20 - 30 knots, and none of the reliable models for tropical cyclone formation is predicting development during the coming five days. In their 8 am EST Tropical Weather Outlook, NHC gave the disturbance 5-day formation odds of 10%.

Jeff Masters

Hurricane

Atlantic November Hurricane Outlook

By: JeffMasters, 3:01 PM GMT on November 01, 2013

The tropical Atlantic is quiet, with no threat areas to discuss, and no reliable models predicting development of a tropical cyclone during the coming five days. So, are we all done for 2013? Or will this unusually quiet hurricane season spawn a Tropical Storm Melissa? The large-scale circulation pattern over the first half of November favors upward-moving air and an increased chance of tropical storm development over the Atlantic, due to the current positioning of the Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days. By mid-November, this pattern will favor sinking air over the tropical Atlantic, making a late-November tropical storm an unlikely proposition. Wind shear has risen to high levels prohibitive for tropical storm formation over the Gulf of Mexico and the waters near the Bahama Islands, and is expected to remain very high through mid-November, according to the latest run of the GFS model. However, wind shear over the Caribbean is likely to be average to below average for the next two weeks, making tropical storm formation possible there. The oceans are certainly warm enough to support development, with Sea Surface Temperatures (SSTs) in the Caribbean 0.2°C (0.37°F) above average, and well above the 26°C (79°F) threshold typically needed to support tropical storm formation (Figure 1.) Dry air--which has dominated the tropical Atlantic during the 2013 hurricane season--will continue to make its presence felt over the Caribbean during portions of the coming two weeks, though, reducing the odds of development. The African Monsoon is quiet this time of year, and we no longer have African waves coming off the coast of Africa that can act as the seeds for formation of a tropical storm in the Caribbean. If we do get a tropical storm, it will probably be in the Western Caribbean, where the tail end of a cold front lingers long enough over warm waters to generate some heavy thunderstorms and acquire a spin. A cold front capable of triggering such a disturbance will arrive over the Western Caribbean November 8 - 9, but the GFS and ECMWF models are not suggesting any development from this front. Taking all these factors into account, I predict that the Atlantic hurricane season of 2013 is over, with just a 20% chance of another named storm this season.


Figure 1. Sea surface temperatures in the Atlantic on November 1, 2013. The black line marks the 26°C (79°F) isotherm, which is the boundary where tropical storm formation can typically occur. A large portion of the Atlantic is still capable of supporting tropical storm formation, but the Gulf of Mexico is getting marginal.

Climatology of November Atlantic tropical cyclones
Since the active hurricane period we are in began in 1995, eleven of the eighteen years (61%) have seen one or more Atlantic named storms form after November 1, for a total of sixteen November/December storms:

2011: Tropical Storm Sean on November 8
2009: Hurricane Ida on November 4
2008: Hurricane Paloma on November 6
2007: Tropical Storm Olga on December 11
2005: the "Greek" storms Gamma, Delta, Epsilon, and Zeta
2004: Tropical Storm Otto on November 29
2003: Odette and Peter in December
2001: Hurricane Noel on November 5 and Hurricane Olga on November 24
1999: Hurricane Lenny on November 14
1998: Hurricane Nicole on November 24
1996: Hurricane Marco on November 19

Only three of these storms (19%) caused loss of life: Hurricane Ida of 2009, which killed one boater on the Mississippi River; Tropical Storm Odette of 2007, whose floods killed eight people in the Dominican Republic; and Hurricane Lenny of 1999, which killed fifteen people in the Lesser Antilles. "Wrong-way Lenny" was both the deadliest and the strongest November hurricane on record (Category 4, 155 mph winds). There have been only seven major Category 3 or stronger hurricanes in the Atlantic after November 1. Part of the reason for the relatively low loss of life for November storms is that they tend to form from extratropical low pressure systems that get cut off from the jet stream and linger over the warm waters of the subtropical Atlantic. These type of systems typically get their start in the middle Atlantic, far from land, and end up recurving northeastwards out to sea. The most recent November named storm, Tropical Storm Sean of 2011, was an example of this type of storm. However, as I noted in the wake of Hurricane Tomas of November 2010 in my blog post, Deadly late-season Atlantic hurricanes growing more frequent, "It used to be that late-season hurricanes were a relative rarity--in the 140-year period from 1851 - 1990, only 30 hurricanes existed in the Atlantic on or after November 1, an average of one late-season hurricane every five years. Only four major Category 3 or stronger late-season hurricanes occurred in those 140 years, and only three Caribbean hurricanes. But in the past twenty years, late-season hurricanes have become 3.5 times more frequent--there have been fifteen late-season hurricanes, and five of those occurred in the Caribbean. Three of these were major hurricanes, and were the three strongest late-season hurricanes on record". Dr. Jim Kossin of the University of Wisconsin published a 2008 paper in Geophysical Research Letters titled, "Is the North Atlantic hurricane season getting longer?" He concluded that yes, there is an "apparent tendency toward more common early- and late-season storms that correlates with warming Sea Surface Temperature but the uncertainty in these relationships is high". The recent increase in powerful and deadly November hurricanes would seem to support this conclusion.


Figure 2. The strongest hurricane on record in the Atlantic in November, Hurricane Lenny, takes aim at the Lesser Antilles on November 17, 1999. Image credit: NOAA.

Typhoon Krosa takes aim at China
Category 2 Typhoon Krosa is headed towards China's Hainan Island after battering the northern end of Luzon, the main Philippines Island, on Thursday. Krosa hit extreme northeast Luzon near 06 UTC (2 am EDT) on October 31, as a Category 2 storm with 105 mph winds. No injuries or major damage have been reported so far from the storm. Satellite loops show an impressive system with a large eye and plenty of intense thunderstorms. The typhoon will slowly weaken over the weekend as it encounters higher wind shear and cooler waters, before brushing China's Hainan Island as a tropical storm on Sunday.

The GFS and European models predict that the Philippines will see a new tropical storm or typhoon hit the islands on Friday, November 8.


Figure 3. MODIS satellite image of Typhoon Krosa taken at 05:05 UTC on November 1, 2013. At the time, Krosa was a Category 1 storm with winds of 85 mph. Image credit: NASA.

TD 18-E in Eastern Pacific will bring heavy rains to Mexico
In the Eastern Pacific, Tropical Depression 18-E has spun up south of Baja, Mexico. Satellite loops show that the depression is poorly organized, but has plenty of intense thunderstorms. Heavy rains from TD 18-E will begin affecting the southern Baja Peninsula and portions of Mainland Mexico to its east on Sunday. The 06Z Friday run of the HWRF model predicted that Mainland Mexico near Manzanillo could see 4 - 8 inches of rain from the system. Moisture from the storm will spread northeastwards into Southwest Texas by Tuesday.

New "Tipping Points" episode, "Arctic Permafrost Peril", airs Saturday at 9 pm EDT/8 pm CDT
“Tipping Points”, a landmark 6-part TV series that began last Saturday on The Weather Channel, airs for the third time on Saturday night, November 2, at 9 pm EDT. The new episode, "Arctic Permafrost Peril", goes on an expedition across Alaska to the North Pole to explore the ticking time bomb of the permafrost melt and the release of tons of carbon dioxide and methane. The series is hosted by polar explorer and climate journalist Bernice Notenboom, the first woman to perform the remarkable triple feat of climbing Mt. Everest and walking to the North and South Poles. In each episode, Notenboom heads off to a far corner of the world to find scientists in the field undertaking vital climate research to try to understand how the climate system is changing and how long we have to make significant changes before we reach a tipping point--a point of no return when our climate system will be changed irreversibly.


Figure 4. "Tipping Points" host Bernice Notenboom watches as scientists take permafrost measurements near the Alaska Pipeline.

I'll have a new post by Monday at the latest.

Jeff Masters

Hurricane


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Category 6™

About

Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather

Ad Blocker Enabled