Dr. Jeff Masters' WunderBlog

Extreme storms and extreme heat hit the U.S.

By: JeffMasters, 5:50 PM GMT on June 30, 2012

A violent line of organized severe thunderstorms called a derecho swept across the U.S. from Illinois to Virginia on Friday, damaging houses, toppling trees, bringing down power lines. The storms killed six people in Virginia, two in New Jersey, and one in Maryland, and left at least 3.4 million people without power. The thunderstorms in a derecho (from the Spanish phrase for "straight ahead") create violent winds that blow in a straight line. The traditional definition of a derecho is a thunderstorm complex that produces a damaging wind swath of at least 240 miles (about 400 km), featuring a concentrated area of thunderstorm wind gusts exceeding 58 mph (93 km/hr.) A warm weather phenomenon, derechos occur mostly in summer, especially June and July in the Northern Hemisphere. They can occur at any time of the year and occur as frequently at night as in the daylight hours. As seen on our wundermap with the "go back in time" feature turned on, Friday's derecho began near Chicago in the early afternoon, then marched east-southeast, peaking in intensity over Virginia and Washington D.C. on Friday evening. The derecho was unusually intense due to the extreme heat, which helped create an unstable atmosphere with plenty of energy to fuel severe thunderstorms.


Figure 1. Radar image from our wundermap with the "go back in time" feature turned on for 11 pm EDT Friday June 29, 2012, showing the derecho over Washington D.C. and Baltimore. Click on the "hour" button above the wundermap to advance the time by one hour to watch the progress of the derecho across the country.


Figure 2. NOAA's Storm Prediction Center (SPC) logged 871 reports of damaging winds on Friday. Twenty one of these reports were for winds over 80 mph. The highest wind gust was in Oswego, Illinois: 92 mph.



Figure 3. A dramatic change in the weather in Buckeye land: the temperature at Ohio State University in Columbus, Ohio dropped from 97°F to 68° after passage of Friday's derecho. The storm brought a wind gust of 82 mph to campus, and 0.86" of rain.

Historic heat wave topples Dust Bowl-era extreme heat records
A historic heat wave on a scale and intensity not seen in the U.S. since the great heat waves of the 1930s Dust Bowl era set new all-time heat records for at least ten major cities Friday. According to wunderground's weather historian Christopher C. Burt, fifteen of the 303 major cities he maintains records for on the wunderground extremes page have set all-time heat records in the past four days. The only year with more all-time heat records is 1936, when 61 cities set all-time heat records. In 2011, which had the 2nd warmest summer in U.S. history, only ten of the 303 cities set all-time heat records during the entire summer. With the the hottest month of the year (July) still to come, 2012 threatens to rival the great Dust Bowl summer of 1936 for extreme heat.

All-time records for any date tied or broken on Friday:

109° Nashville, TN (old record 107° 7/28/1952
109° Columbia, SC (old record 107° on two previous occasions)
109° Cairo, IL (old record 106° on 8/9/1930)
108° Paducah, KY (ties same on 7/17/1942
106° Chattanooga, TN (ties same on 7/28/1952)
105° Raleigh, NC (ties same on 8/21/2007 and 8/18/1988)
105° Greenville, SC (old record 104° 8/10/2007 although 106° was recorded by the Signal Service in July 1887)
104° Charlotte, NC (ties same on 8/9 and 10/2007 and 9/6/1954)
102° Bristol, TN (ties same on 7/28/1952-this site now known as `Tri-State Airport')
109° Athens, GA. This is just 1° shy of the Georgia state record for June of 110° set at Warrenton in 1959.

All-time state June heat records set Friday:

113° Smyrna, TN (old record 110° in Etowah in June 1936)
109° Cairo, IL (old record 108° in Palestine in June 1954)

Also of note: Atlanta, GA hit 104° (its all-time June record), and just 1° shy of its all-time record of 105° set on 7/17/1980. The forecast for Atlanta on Saturday calls for a high of 105°F, which would tie for the hottest day in the city's history.

Wunderground's weather historian Christopher C. Burt has a new post called The Amazing June Heat Wave of 2012 Part 1: The West and Plains June 23 - 27 summarizing the early portion of this week's historic heat wave. He plans to make a follow-up post on Sunday summarizing the records set on Friday and Saturday.

Relatively quiet in the Atlantic
An area of heavy thunderstorms, associated with an upper level low pressure system, has developed in the Gulf of Mexico along the Texas coast. This disturbance will probably move ashore over Texas before development into a tropical depression can occur, and NHC is giving it a 0% chance of development. The tropical wave approaching the Lesser Antilles (Invest 97L) has dissipated due to dry air, and is no longer a threat. None of the reliable computer models are developing anything during the next seven days.

Jeff Masters

Extreme Weather Heat

Updated: 8:31 PM GMT on June 30, 2012

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Air quality degrades as heat spreads east

By: angelafritz , 6:53 PM GMT on June 29, 2012

For the seventh day in a row we're talking about heat as it spreads into the Mid-Atlantic and East Coast. The hottest temperatures in the country will be from Missouri southeast to Georgia and north to the Washington D.C. area. Why not Florida? Moisture tends to keep the temperature regulated; the worst heat waves this country has seen have also coincided with widespread drought. Given the extreme to exceptional drought that many states can't get rid of, this heat wave isn't all that surprising. Air quality is becoming more of an issue the longer the heat sticks around. Air quality alerts have been issued for many major cities from Kansas City to New York, including Chicago, Detroit, and Atlanta. Chicago is seeing some relief from the heat today in the form of thunderstorms—northeast Illinois and northwest Indiana are under a severe thunderstorm watch. Washington D.C. is pushing its all-time record high of 106°, which is the high that BestForecast is going with. You can see the all-time record highs for almost all major cities here.


Figure 1. BestForecast high temperature for Friday.

Our Weather Historian, Christopher C. Burt, will likely post two blogs today and tomorrow this week's heat, but for now, he wraps up Thursday's significant temperature records:

• 109° in Chesterfiled, Missouri (well short of state monthly record of 112°)
• 108° in Lawrenceville, Illinois (ties all-time state June monthly record of 108° at Palestine in June 1954)
• 108° in Huntingsburg, Indiana (well short of state monthly record of 111°)
• 107° in Defiance, Ohio (1° short of all-time state June record-108° in Germantown in 1934)
• 111° in Evening Shade, Arkansas (short of state June record of 113° in 1936)
• 108° in Smyrna, Tennessee (short of 110° state record in 1936)
• 107° in Little Rock, Arkansas (all-time June monthly record)

Waldo Canyon Fire now 15% contained

The Denver Post is reporting that 346 homes have been lost to the Waldo Canyon Fire, which is burning northwest of Colorado Springs. They also report that one person has died and another is missing in the area of the blaze. The fire has been 15% contained since Thursday night, and the acreage is down to 16,750, welcome news to a terrified city.


Figure 2. Satellite imagery of Invest 97L, which is expected to drift west into the Caribbean over the next few days.

Invest 97L

A tropical wave in the central main development region of the North Atlantic is still producing thunderstorm activity as it moves west, and the National Hurricane Center has increased its chance of development to 20%. 97L's circulation continues to be moderate and in the past day has realigned with the thunderstorm activity, which is likely why NHC gave the go to invest the wave and begin running models on it. This wave continues to be in some moderate wind shear, 10-15 knots, and sea surface temperature is around average, 28° C (82° F), which is warm enough to support tropical development. Many of the track models are forecasting 97L to continue trekking west into the Caribbean, crossing the Lesser Antilles around July 1.

Angela

Hurricane Heat Air and Water Pollution Fire

Updated: 7:02 PM GMT on June 29, 2012

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Heat wave shifts to the Midwest; Waldo Canyon Fire still 5% contained

By: angelafritz , 8:17 PM GMT on June 28, 2012

The ridge of high pressure causing this week's record-setting heat wave continues to drift east today, and will inflict extreme June heat across most of the central U.S. and Midwest on Thursday. Triple-digit heat (and heat indices) will be widespread from the Midwest (Chicago, Detroit, Cleveland) to the Mississippi and Ohio River Valleys (St. Louis, Louisville, Memphis). Ann Arbor, Michigan has reached 100° as of 4pm EDT. Heat advisories spread from Kansas north to Michigan, and as far southeast as North and South Carolina.

On Wednesday, 16 all-time record highs were broken or tied from Wyoming to Kansas, and 47 month-of-June records were either broken or tied. 66 warm overnight low records were also tied, 8 of which were all-time records for the month of June. The temperature did not get below 81° in Lamar, Colorado Tuesday night. The overnight low temperature is an important barometer for public health and safety in extreme heat waves; if the mercury does not drop significantly, our bodies (the sick and elderly, in particular) cannot recuperate.


Figure 1. Heat advisories (pink) from Kansas north to Michigan, and as far southeast as North and South Carolina on Thursday, where heat indices are expected to reach 105, as much as 110 in some places.

Our Weather Historian, Christopher C. Burt, wraps up yesterday's significant temperature records:

• Lamar, Colorado hit 112°, which is the city's hottest ever reading, beating 111° measured a few days ago and also on July 13, 1934.

• Dodge City, Kansas finally broke free of its multiple 110° previous all-time records with 111° on Wednesday. Dodge City has one of longest periods of record in the United States, with temperature records beginning on September 15, 1874.

• Hill City, Kansas hit 115° as it did on Tuesday as well, again just 1° short of all-time Kansas STATE June record of 116° set at Hugoton on June 25, 1911.

• Tucumcari, New Mexico hit 108°, just 1° short of all-time record as was the case in Goodland, Kansas and many others.

Waldo Canyon Fire gains 5,000 acres, still 5% contained

18,500 acres (up from 13,5000 on Wednesday) have been consumed, and $3.2 million spent fighting, in the Waldo Canyon Fire which is burning northwest of Colorado Springs and encroaching on the city. The fire remains 5% contained. Around 32,000 people have been evacuated as of Thursday morning as fire fighters continue to battle the blaze, with some help from the weather. Colorado Springs is forecast to reach 97° on Thursday, though it will be slightly cooler in the hills where the majority of the fire is burning. The red flag warnings have been dropped as wind speeds calm to 5-10 mph out of the northwest. However, humidity will still be relatively low, around 15% at the peak heat of the day. Thunderstorms are in the forecast, which creates the threat of lightning-induced fires


A giant plume from the Waldo Canyon Fire hovers high above Garden of the Gods near Colorado Springs, Colo. on Saturday, June 23, 2012. The fire is zero percent contained and has consumed 2500 acres. Voluntary and mandatory evacuations were taking place across the west side of Colorado Springs. Tankers were dropping fire retardant in front of the advancing flames. (AP Photo/Bryan Oller)

In the Tropics…

An African easterly wave in the central main development region of the North Atlantic is still producing some disorganized thunderstorm activity. The circulation in the wave is moderate but somewhat displaced from the strongest thunderstorm activity, though given the moderate wind shear the wave is experiencing that's not surprising. Sea surface temperature is around average, 28° C (82° F), which is warm enough to support tropical development. The National Hurricane Center continues to give this wave a 10% chance of developing over the next 48 hours.

There are a couple more tropical waves expected to leave the coast of Africa in the next week or so, neither of which are showing any signs of development in the models.

Angela

Heat Fire Extreme Weather

Updated: 5:56 PM GMT on June 29, 2012

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Heat wave shifts to the Midwest; Waldo Canyon Fire still 5% contained.

By: angelafritz , 8:17 PM GMT on June 28, 2012

The ridge of high pressure causing this week's record-setting heat wave continues to drift east today, and will inflict extreme June heat across most of the central U.S. and Midwest on Thursday. Triple-digit heat (and heat indices) will be widespread from the Midwest (Chicago, Detroit, Cleveland) to the Mississippi and Ohio River Valleys (St. Louis, Louisville, Memphis). Ann Arbor, Michigan has reached 100° as of 4pm EDT. Heat advisories spread from Kansas north to Michigan, and as far southeast as North and South Carolina.

On Wednesday, 16 all-time record highs were broken or tied from Wyoming to Kansas, and 47 month-of-June records were either broken or tied. 66 warm overnight low records were also tied, 8 of which were all-time records for the month of June. The temperature did not get below 81° in Lamar, Colorado Tuesday night. The overnight low temperature is an important barometer for public health and safety in extreme heat waves; if the mercury does not drop significantly, our bodies (the sick and elderly, in particular) cannot recuperate.


Figure 1. Heat advisories (pink) from Kansas north to Michigan, and as far southeast as North and South Carolina on Thursday, where heat indices are expected to reach 105, as much as 110 in some places.

Our Weather Historian, Christopher C. Burt, wraps up yesterday's significant temperature records:

• Lamar, Colorado hit 112°, which is the city's hottest ever reading, beating 111° measured a few days ago and also on July 13, 1934.

• Dodge City, Kansas finally broke free of its multiple 110° previous all-time records with 111° on Wednesday. Dodge City has one of longest periods of record in the United States, with temperature records beginning on September 15, 1874.

• Hill City, Kansas hit 115° as it did on Tuesday as well, again just 1° short of all-time Kansas STATE June record of 116° set at Hugoton on June 25, 1911.

• Tucumcari, New Mexico hit 108°, just 1° short of all-time record as was the case in Goodland, Kansas and many others.

Waldo Canyon Fire gains 5,000 acres, still 5% contained

18,500 acres (up from 13,5000 on Wednesday) have been consumed, and $3.2 million spent fighting, in the Waldo Canyon Fire which is burning northwest of Colorado Springs and encroaching on the city. The fire remains 5% contained. Around 32,000 people have been evacuated as of Thursday morning as fire fighters continue to battle the blaze, with some help from the weather. Colorado Springs is forecast to reach 97° on Thursday, though it will be slightly cooler in the hills where the majority of the fire is burning. The red flag warnings have been dropped as wind speeds calm to 5-10 mph out of the northwest. However, humidity will still be relatively low, around 15% at the peak heat of the day. Thunderstorms are in the forecast, which creates the threat of lightning-induced fires


A giant plume from the Waldo Canyon Fire hovers high above Garden of the Gods near Colorado Springs, Colo. on Saturday, June 23, 2012. The fire is zero percent contained and has consumed 2500 acres. Voluntary and mandatory evacuations were taking place across the west side of Colorado Springs. Tankers were dropping fire retardant in front of the advancing flames. (AP Photo/Bryan Oller)

In the Tropics…

An African easterly wave in the central main development region of the North Atlantic is still producing some disorganized thunderstorm activity. The circulation in the wave is moderate but somewhat displaced from the strongest thunderstorm activity, though given the moderate wind shear the wave is experiencing that's not surprising. Sea surface temperature is around average, 28° C (82° F), which is warm enough to support tropical development. The National Hurricane Center continues to give this wave a 10% chance of developing over the next 48 hours.

There are a couple more tropical waves expected to leave the coast of Africa in the next week or so, neither of which are showing any signs of development in the models.

Angela

Heat Fire Extreme Weather

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More record-setting heat; Waldo Canyon Fire consumes 15,000 acres

By: angelafritz , 7:17 PM GMT on June 27, 2012

Tuesday's heat toppled many records in the Central U.S., particularly in Colorado, Nebraska, and Kansas. On Monday and Tuesday combined, 11 locations tied or broke their all-time record high temperature, 78 locations broke their all-time record high for the month of June, and 382 daily high records fell. Some notable Tuesday records from our Weather Historian:

115° in McCook, Nebraska is the all-time record for any month. The old records for site are 114° 7/20/1932 and for June 112° 6/5/1933—both set in the heat waves of the 1930s. Yesterday's 115° at Mc Cook also broke the all-time Nebraska state June record of 114° which was set in Franklin in 1936.

105° in Denver, Colorado, ties Monday's all-time record, and ties the 5-day record for number of days above 100°.

101° in Colorado Springs, Colorado is the all-time undisputed record high for any month.

111° in Miles City, Montana is the all-time high for any month.

111° in Lamar, Colorado tied that all-time heat record in any month.

115° in Hill City, Kansas is the new June record, but fell short of all-time 117° reading, and one degree short of Kansas state June record.

110° in Dodge City, Kansas ties the all-time high for any month, which was just set last June.

Wheat Ridge, Colorado (103°) and Cedar Bluff Dam, Kansas (110°) also tied their all-time record highs on Tuesday. Our Weather Historian Christopher C. Burt, who mused that this heat wave is starting to shape up like the record setting heat waves of the 1930s, will have a full-length post on this week's incredible heat wave on Friday. Today the heat shifts eastward, with eastern Iowa and northwest Illinois in an excessive heat watch, and eastern Kansas and western Missouri in an excessive heat warning. St. Louis could start to see 100°+ today, and Chicago will likely have their warmest day on Thursday. This heat wave will reach the eastern U.S. by Friday.

Waldo Canyon Fire engulfs parts of Colorado Springs

Firefighters are "on the offensive" on Wednesday as they fight the Waldo Canyon Fire, which started Saturday afternoon for reasons unknown. The fire is 5% contained as of Wednesday afternoon, though firefighters are using triage protocol, according to the AP, to save the homes that they are able to save. 30,000 people have fled their homes on Wednesday as the fire grew to over 15,000 acres. The region remains in a red flag warning as conditions continue to be unfavorable for fighting both this and the High Park fire, which continues to burn west of Fort Collins. Humidity is expected to remain around or less than 10%, and winds could gust up to 50 mph.


Figure 1. The Waldo Canyon Fire as seen on Wundermap, which is burning just northwest of Colorado Springs, and is 5% contained. This fire has engulfed over 15,000 acres since it began on Saturday, as firefighters try to fight the blaze under weather conditions favorable for wildfires.

Debby Says Farewell

Tropical Depression Debby is in the Atlantic and moving further out to sea and rainfall is winding down. Over the past week, Debby has dropped more than 20 inches of rain over northern Florida, and widespread amounts of 10+ inches as far south as Port Charlotte. While still classified as tropical, Debby seems to be losing her tropical characteristics as it merges with the frontal boundary that guided it across Florida. The depression continues to be hammered by westerly wind shear, and could be classified as post-tropical or dissipate all together soon.


Figure 2. Rainfall accumulation over the past 7 days as of June 27. Debby has dropped more than 20 inches of rain over northern Florida, and widespread amounts of 10+ inches as far south as Port Charlotte. Image modified from NWS.

Meantime, in the main development region of the Atlantic, the National Hurricane Center is giving an African easterly wave a 10% chance of developing into a tropical cyclone over the next 48 hours. This is the first main development region activity we've seen so far this season, though its peak usually doesn't happen until later in the Summer and early Fall. This wave is producing some thunderstorm activity which is visible on satellite, and it appears to have moderate mid-level circulation. Wind shear in the region is relatively low, only 10-15 knots, and the wave is moving into a more favorable wind shear zone, which will remain until it reaches the Lesser Antilles. The moisture in and around this wave is also relatively low. I would also put this wave's probability of development at minimal over the next few days.

Angela

Heat Fire Hurricane Extreme Weather

Updated: 8:39 PM GMT on June 27, 2012

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Tropical Storm Debby makes landfall in Florida

By: angelafritz , 9:07 PM GMT on June 26, 2012

Debby continues to weaken this afternoon, but remains a tropical storm with maximum sustained winds of 40 mph. The storm's center of circulation made landfall this afternoon near Steinhatchee, Florida. Hurricane hunters continue to find surface wind speeds that just meet tropical storm criteria and surface buoys on Wundermap are all clocking in at or below 30 mph. The storm's upper-level circulation is being stretched out into the Atlantic by the same steering forces that will transport it to the other side of Florida, and this combined with dry air has led to a messy-looking tropical cyclone over the past couple of days. Though there was no lack of rain yesterday in the Florida panhandle, Debby has certainly been weakened by the dry air that has wrapped into its center (figure 1). Water vapor imagery from satellite shows Debby's center is almost completely void of moisture, though rain continues to fall on the northeast side of the storm where moisture is still available. A 6 foot wide, 12-15 foot deep sinkhole swallowed a small portion of I-10 in Madison County west of Jacksonville, Florida, this morning, where heavy rain continues, though this hole will likely be filled and the lane reopened by tomorrow morning. Wind shear around 20 knots is also keeping Debby at bay, but the real disrupter is the lack of moisture.


Figure 1. Where's Debby? On the left: visible satellite imagery. On the right: water vapor satellite imagery, where the dry air ranges from black to rusty orange. Debby's center is almost completely void of moisture. These images were captured around 1pm EDT.

Forecast for Debby
The forecast for Debby continues to be similar to previous forecasts. The storm will likely continue to lose strength as it moves over Florida this evening and Wednesday, but could gain some momentum again when it reaches the yet untapped Atlantic water. There's a high chance Debby will be downgraded to tropical depression status this evening. The HPC continues to forecast up to 8 inches of rain for far northeast Florida over the next 5 days, likely because of the slight strengthening forecast to occur on Thursday and beyond. Debby's center will most likely be over Atlantic water Wednesday night.


Figure 2. Advisory map for the U.S. Tuesday afternoon. Heat advisories (pink) blanket the central U.S. This heat is expected to move eastward over the next few days as the ridge of high pressure advances.

The Heat Continues

Record highs continue to fall Tuesday afternoon in the central U.S., where Denver, Colorado had its fifth consecutive day of triple-digit heat after it reached 100°F at 1pm MDT, and could continue to rise this afternoon. This ties the all-time record for consecutive 100°F+ days. Nebraska and Kansas are particularly toasty this afternoon; McCook, Nebraska has reached 113°F so far, and Hill City, Kansas is up to 112°F. Though, to put that in perspective, the state record for Nebraska is 118°F, and the state record for Kansas is 121°F.

The heat moves east tomorrow, and by Thursday, many of the major Midwest cities are forecast to be in the triple-digits, including Chicago, St. Louis, and Indianapolis. By Friday the heat will be beating down on the East Coast. In the meantime out west, the forecast high in Fresno for this weekend is 82°F, which would tie as the coolest final weekend in June on record, according to the Hanford forecast office.

Angela

Hurricane Heat

Updated: 9:10 PM GMT on June 26, 2012

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Debby dumps 20 inches of rain; 105° in Denver: hottest day on record

By: JeffMasters, 11:52 AM GMT on June 26, 2012

Florida, the Sunshine State, continues to be the thoroughly sodden state, thanks to torrential rains from slow-moving Tropical Storm Debby. On Monday, Debby spawned an area of intense thunderstorms that blew up over the Florida Panhandle, just east of Apalachicola. A weather station in Wakulia County, 4 miles east of Saint Marks, Florida, recorded 12.99" on rain in just 12 hours, bringing the 48-hour rainfall total at the site to 20.96". Several other stations in Wakulia Country also recorded rainfall amounts in excess of 20 inches, and the heavy rains caused moderate to major flooding on area rivers. Debby did not spawn any tornadoes on Monday, thankfully.


Figure 1. Radar-estimated rainfall from Tropical Storm Debby shows an area of extreme rainfall in excess of 15 inches has affected the Florida Panhandle.

Dry air and high wind shear continue to disrupt Debby. Our Wundermap for the surrounding ocean areas shows that winds at almost all buoys and coastal stations along the Gulf Coast were below 25 mph at 7 am EDT. Visible satellite loops show Debby has virtually no heavy thunderstorms near its center of circulation, which will severely limit its potential for intensification. The heavy thunderstorms of Debby are mostly on the east and north sides. Upper-level winds out of the west creating a high 20 - 25 knots of wind shear that continues to drive dry air into Debby's core. This dry air can be seen on Water vapor satellite loops. Ocean temperatures are about 27.5°C (81°F) in the Northern Gulf of Mexico, which is about 1°F above average, but these waters do not extend to great depth, which will limit how strong Debby can get.


Figure 2. True-color visible Terra satellite image of Debby taken at 12:30 pm EDT Monday June 25, 2012. At the time, Debby had top winds of 45mph. Note the heavy thunderstorms on the north side of the center, which were dumping extremely heavy rains over the Florida Panhandle that caused major flooding on area rivers. Image credit: NASA.

Forecast for Debby
Debby's slow motion will make rainfall the primary threat from the storm, though tornadoes will continue to be a threat over the next few days. NOAA's Storm Prediction Center has placed most of Florida in its "Slight Risk" area for severe weather today. The slow motion of Debby will inhibit intensification of the storm by stirring up cooler waters from the depths to the surface. Debby's close proximity to land places a portion of its circulation over land, which will also tend to slow down intensification. Wind shear is expected to remain in the high range through Wednesday, and given the storm's other problems, significant intensification before landfall on Florida's Gulf Coast is unlikely.

Denver's 105°: hottest temperature in city history
The mercury soared to 105° in Denver, Colorado on Monday, tying the record for the hottest temperature ever measured in the city. The city also hit 105° on July 20, 2005 and August 8, 1878. Yesterday's 105° reading was the city's fourth consecutive day in the triple digit heat. The city's record streak of 100°+ days is five, set in 1989 and again in 2005. Denver's forecast today calls for highs of 100 - 104°, so the city will likely tie its all-time mark for consecutive 100°+ days.

In many respects, the extreme heat that has scorched Colorado since Saturday is the state's most intense heat wave in recorded history. According to wunderground's weather historian Christopher C. Burt, Saturday's 114° reading in Las Animas tied for the hottest temperature ever measured in the state of Colorado. Two other 114° readings have occurred in Colorado history: in Las Animas on July 1, 1933, and in Sedgwick on July 11, 1954. Colorado Springs tied its all-time record for warmest temperature ever measured on both Saturday and Sunday, with readings of 100°. The record heat in Colorado has exacerbated numerous destructive wildfires, and the Governor reported over the weekend that half of the nation's firefighting fleet has been deployed to Colorado. On Sunday, a wildfire that grew to more than 3 square miles near Colorado Springs drove 11,000 residents (2% of the city's population) out of their homes. In Fort Collins, the mercury hit 102° on Sunday, just 1° below the city's all-time hottest temperature of 103° set on Jul 21, 2005. The heat did no favors for firefighters struggling to the contain the massive 81,000 acre High Park fire fifteen miles northwest of Fort Collins. The fire is the second largest and most destructive wildfire in Colorado's history, and is 45% contained. La Junta, CO hit 110° on Sunday, tying its all-time hottest temperature record, set on June 28, 1990. Today is the last day of exceptional heat for Colorado, as the ridge of high pressure responsible slides to the east, bringing record-breaking heat to the Midwest instead.

Jeff Masters

Hurricane Heat

Updated: 11:53 AM GMT on June 26, 2012

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Debby lingers in the Gulf, bringing heavy rain, flooding to Florida

By: angelafritz , 9:26 PM GMT on June 25, 2012

Debby remains a raggedy-looking tropical storm with maximum sustained winds of 45 mph. The hurricane hunter mission that ended around 1pm ET found a minimum central pressure of 995 mb and much weaker winds that it had found on previous missions. Despite Debby's less-than-organized appearance, the storm is still managing to dump buckets on Florida, and in particular today, the panhandle. A burst of thunderstorm activity has exploded on the northern side of Debby, and Tallahassee, Florida and it's southern neighbors are getting the worst of the storm's rain this afternoon as it rotates in place. Weather stations near Tallahassee have recorded anywhere from 2 to 9 inches of rain so far today. The strongest wind speeds reported from buoys are around 30 mph this afternoon. The storm's moisture is still confined to the north and east of the center, as a region of dry air continues to wrap in from the south and west. Visible satellite imagery illustrates just how dry Debby is on the southwest, as well as the strong thunderstorm activity that is expected to continue over Florida for the next couple of days. Debby has begun to create a bit of storm surge in the Apalachee Bay area, with reports from St. Marks, Florida that the storm surge has reached the town, though high tide is not for another 2 hours.


Figure 1. Monday afternoon visible satellite imagery of Tropical Storm Debby.


Figure 2. 5-day forecast rainfall from the Hydrometeorological Prediction Center. Rainfall in excess of 15 inches is expected in northern Florida as Debby makes its slow way across the state and into the Atlantic.

Forecast for Debby
Debby continues to drift to the northeast this afternoon, a track that will continue, slowly, over the next couple of days, before it finally crosses Florida, which will likely happen Wednesday and Thursday of this week. The National Hurricane Center's 5pm forecast track is similar to the tracks from earlier today, though the timing has sped up a bit, with landfall occurring Wednesday afternoon. All of the models now agree that Debby will continue moving northeast and gradually turn to the east as it crosses over Florida into the Atlantic. In terms of intensity, the Hurricane Center is predicting that the storm will remain a storm through Wednesday, after which it will likely diminish to tropical depression status. Given the current state of the storm and the dry air that continues to wrap in, it's possible this could happen earlier than Wednesday. Interestingly, the GFDL is suggesting Debby could gain some strength as it crosses Florida, and the ECMWF's earlier run actually thinks Debby will rapidly intensify when it reaches the yet untapped warm waters of the Gulf Stream in the Atlantic and tracks northeast. It's worth nothing that the ECMWF is the only model suggesting this intensity outcome, though all the models have a similar track. In any case, Debby will remain a rainmaker for the rest of the week, and some storm surge is possible, especially in the Big Bend. The SLOSH model, which predicts storm surge heights, suggests this area could see up to a 6 foot storm surge. The coastal flooding will be the worst in the Apalachee Bay region, where high tide occurs from around 7am to 9am EDT.

Angela

Hurricane

Updated: 4:04 AM GMT on June 26, 2012

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Debby stalls, drenches Florida; 114° in Colorado ties state heat record

By: JeffMasters, 1:09 PM GMT on June 25, 2012

Tropical storm warnings continue to fly from Alabama eastward to Suwannee, Florida, as Tropical Storm Debby sits motionless over the Gulf of Mexico. On Sunday, Debby spawned a multitude of severe thunderstorms over much of Florida, which brought torrential rains, damaging winds, and numerous tornadoes. NOAA's Storm Prediction Center logged 20 preliminary tornado reports on Sunday, and a tornado in Venus, Florida killed one person. Venus is in Central Florida, between Port St. Lucie and Sarasota. Another person is missing in Alabama, swept away by rough surf. The heaviest rains of Debby affected the Tampa Bay region, where over ten inches were reported at several locations. The Tampa Bay airport picked up 7.11 inches on Sunday. It's a good thing this isn't the week of the Republican National Convention, which is scheduled for late August in Tampa! Minor to moderate flooding is occurring at three rivers near Tampa, and flooding has been limited by the fact the region is under moderate to severe drought.


Figure 1. Radar-estimated rainfall from Tropical Storm Debby has totaled over 6 inches (orange colors) along a swath from Tampa to Ocala.

Winds from Debby have fallen considerably since Sunday, thanks to a slug of dry air that wrapped into Debby's core, disrupting the storm. Our Wundermap for the surrounding ocean areas shows that winds at almost all buoys and coastal stations along the Gulf Coast were below 30 mph at 8am EDT. The exception was a Personal Weather Station at Bald Point, near Apalachiacola, Florida, which reported sustained winds of 32 mph. An Air Force hurricane hunter aircraft flying through Debby has measured top surface winds of 43 mph as of 9 am EDT. Visible satellite loops show Debby has virtually no heavy thunderstorms near its center of circulation, which will severely limit its potential for intensification today. The heavy thunderstorms of Debby are mostly on the east and north sides. Upper-level winds out of the west creating a moderate 10 - 20 knots of wind shear that continues to drive dry air into Debby's core. This dry air can be seen on Water vapor satellite loops. Ocean temperatures are about 27.5°C (81°F) in the Northern Gulf of Mexico, which is about 1°F above average, but these waters do not extend to great depth, which will limit how strong Debby can get.


Figure 2. True-color visible Aqua satellite image of Debby taken at 3 pm EDT Sunday June 24, 2012. At the time, Debby had top winds of 60 mph. Image credit: NASA.

Forecast for Debby
Debby's slow motion will make rainfall the primary threat from the storm, though tornadoes will continue to be a threat over the next few days. NOAA's Storm Prediction Center has placed most of Florida in its "Slight Risk" area for severe weather today. The slow motion of Debby will inhibit intensification of the storm by stirring up cooler waters from the depths to the surface. Debby's close proximity to land places a portion of its circulation over land, which will also tend to slow down intensification. Wind shear is expected to remain in the moderate range through Wednesday. I expect Debby will begin to build heavy thunderstorms near its core today and Tuesday, with the winds increasing again to 60 mph by Wednesday morning. The latest SHIPS model forecast gives Debby just a 4% chance of undergoing rapid intensification--a 30 mph increase of winds in 24 hours. The 8 am EDT NHC wind probability forecast is giving Debby a 19% chance of becoming a hurricane by early Wednesday morning. Steering currents for Debby are very weak, a the storm should hang out in its current location for several more days. The models continue to have a large spread in where they thing Debby might eventual make landfall, and the official NHC forecast may have large errors for its positions at the 3 - 5 day range.

Colorado's 114°: hottest temperature in state history
The remarkable heat wave that affected Colorado on Saturday and Sunday has tied the all-time heat record for the state. According to wunderground's weather historian Christopher C. Burt, Saturday's 114° reading in Las Animas tied for the hottest temperature ever measured in the state of Colorado. Two other 114° readings have occurred in Colorado history: in Las Animas on July 1, 1933, and in Sedgwick on July 11, 1954.

Colorado Springs tied its all-time record for warmest temperature ever measured on both Saturday and Sunday, with readings of 100°. The city has hit 100° four other times, most recently on July 24, 2003. The record heat in Colorado Springs exacerbated a wildfire that grew to more than 3 square miles on Sunday, driving 11,000 residents (2% of the city's population) out of their homes.

In Fort Collins, the mercury hit 102° on Sunday, just 1° below the city's all-time hottest temperature of 103° set on Jul 21, 2005. The heat did no favors for firefighters struggling to the contain the massive 81,000 acre High Park fire fifteen miles northwest of Fort Collins. The fire is the second largest and most destructive wildfire in Colorado's history, and is 45% contained.

La Junta, CO hit 110° on Sunday, tying its all-time hottest temperature record, set on June 28, 1990.

The heat wave extended into neighboring Kansas, where Hill City hit 114°, tying its all-time warmest June temperature. Tribune, Kansas hit 109°, tying its all-time hottest temperature. Goodland, Kansas hit 109°, its hottest June temperature on record.

Two more days of exceptional heat are predicted for Colorado and Kansas, with the forecast for Denver calling for a high of 101 - 104° on Monday. The city hit 102° on Sunday, just 3° below the hottest temperature ever recorded in Denver, the 105° readings on July 20, 2005 and August 8, 1878.

Jeff Masters

Hurricane Heat

Updated: 1:15 PM GMT on June 25, 2012

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Significant change in forecast track for Tropical Storm Debby

By: angelafritz , 9:40 PM GMT on June 24, 2012

Debby remains a tropical storm at 5pm EDT with maximum sustained winds of 60 mph, and continues to move northeast at 3 mph. Tropical storm-force winds (39 mph) extend 200 miles from the center of the storm. Tropical storm conditions are present or close to being present along the northeast Gulf coast. The biggest change in the 5pm update from the National Hurricane Center is the forecast track—see below for discussion on that. Most of the buoys in the northern Gulf are experiencing tropical storm strength winds. Weather stations in Florida have been recording anywhere from 2 to 6+ inches of rain today, and tornado watches have been posted this afternoon. There are nine tornado reports in southern Florida thus far today, one of which caused at least one fatality in Lake Placid. Tornado warnings will likely continue through the night. The National Hurricane Center describes Debby as "sprawling" this afternoon, with most of the thunderstorm activity well-removed from the center of the system. Debby's rainfall extends from Pensacola, Florida north to almost Macon, Georgia, and south and east to Fort Lauderdale, Florida. A hurricane hunter mission flew the storm earlier this afternoon and found no winds to support more than a tropical storm, but flight-level winds were relatively high at almost 90 mph. The next hurricane hunter mission is tentatively scheduled for Wind shear remains moderately strong (10-20 knots) to the north and east of the storm, and is not expected to change over the next couple of days. Debby continues to appear large but hindered by shear on satellite this afternoon. Most of the strong thunderstorm activity is relegated to the north and east, and the southwest portion of the storm remains bare, though not as bare as yesterday.


Figure 1. Sunday afternoon satellite image of Tropical Storm Debby in the Gulf of Mexico.


Figure 2. Track forecast from the National Hurricane Center for Tropical Storm Debby.

Forecast for Debby
Debby continues to drift northeast in defiance of what many of our trusted global forecast models have been suggesting over the past two or three days. The National Hurricane Center has responded to this by making a dramatic and warranted shift in their forecast track. This afternoon the center is calling for potential landfall on Thursday, likely somewhere in the Florida panhandle, though the forecast cone extends from the Mississippi/Alabama border to the Suwannee River in Florida. Models are actually starting to come into somewhat of an agreement now on the forecast track toward Florida. The GFS, UKMET, GFDL, and CMC are suggesting that Debby will continue to drift northeast and make landfall in the southeast panhandle of Florida. The HWRF is the only model that is still going for a west-to-Louisiana solution. The earlier run from the ECMWF backed off on it's Texas forecast, and is appears to becoming around to agreement with the GFS, which has been forecasting a track to the northeast for days, now. In terms of intensity, the Hurricane Center qualifies their forecast with the fact that Debby is going to spend plenty of time over water in the next couple of days, so strengthening is definitely a possibility. However, while sea surface temperature is warm, it will start to cool the longer Debby lingers, and the actual heat available in the northern Gulf is relatively low. Most of the models also suggest Debby will remain a tropical storm. Debby will continue to produce constant, heavy rain along the northeast and eastern Gulf coast over the next few days, and flood watches and warnings have been issued from Mobile, Alabama to southern Florida to reflect that.

Angela

Updated: 9:49 PM GMT on June 24, 2012

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Tropical Storm Debby growing in size and strength

By: JeffMasters, 1:24 PM GMT on June 24, 2012

Tropical storm warnings are flying from Alabama to the Panhandle of Florida and along much of Southeast Louisiana coast, as Tropical Storm Debby inches to the north at 2 mph. The heaviest rains of Debby have moved ashore along much of the Gulf Coast of Florida, with up to two inches of radar-estimated rainfall in the Apalachicola, Florida area so far. Several buoys to the north and east of the center of Debby are receiving tropical storm-force winds, including SGOF1 (56 mph, gusting to 68 mph at 9 am EDT) and buoy 42022, 100 miles off the coast from Tampa (42 mph sustained winds at 7am EDT.) Our Wundermap for the surrounding ocean areas shows a large region of 25 - 45 mph winds off the Southeast Louisiana coast. An Air Force hurricane hunter aircraft flying through Debby at 5,000 feet found an area of 60 mph surface winds about 100 miles south-southwest of Apalachicola, Florida at 7am EDT. Visible satellite loops show the classic signature of a medium-strength tropical storm undergoing substantial wind shear. The heavy thunderstorms of Debby are all on the east and north sides. Upper-level winds out of the southwest creating a moderate 10 - 20 knots of wind shear that is driving dry air to the southwest of the storm into Debby's core. This dry air can be seen on Water vapor satellite loops. However, Debby is steadily overcoming this dry air and wind shear, and the storm has increased in organization, size, and in intensity this morning. Ocean temperatures are about 28.5°C (83°F) in the Central Gulf of Mexico, which is about 1°F above average, but these waters do not extend to great depth, which will limit how strong Debby can get.


Figure 1. Morning radar image of the rainfall from Tropical Storm Debby over coastal Florida.


Figure 2. True-color visible satellite image of Debby taken at 12:45 pm EDT Saturday June 23, 2012, before it became a tropical storm. Image credit: NASA.

Forecast for Debby
Debby's slow motion will make rainfall the primary threat from the storm, with up to 10 inches likely in some regions along the coast from Southeast Louisiana to Pensacola, Florida. Unfortunately, this part of the coast is not under drought, and does not need the rain. Farther to the east, along the rest of the Gulf Coast of Florida, moderate to severe drought prevails, and flooding from Debby will be less of an issue. The slow motion of Debby will also slow down intensification of the storm, since its winds are stirring up cooler waters from the depths to the surface that then cool down the storm. Debby's close proximity to land places a portion of its circulation over land, which will also tend to slow down intensification. Wind shear is expected to remain in the moderate range through Tuesday. The latest SHIPS model forecast gives Debby a 19% chance of undergoing rapid intensification--a 30 mph increase of winds in 24 hours. The 8 am EDT NHC wind probability forecast is giving Debby a 29% chance of becoming a hurricane by early Tuesday morning. Given the current increasing trends in Debby's organization and intensity, these odds should probably be closer to 50%.

Steering currents for Debby are very weak, resulting in an unusually large spread in the model forecasts for where the storm might go. Take your pick from the various model solutions: Debby could make landfall anywhere from South Texas to Tampa Bay. The official NHC track west towards Texas should definitely not be viewed as gospel.


Figure 3. Pick a model, any model: the model forecasts for Debby are all over the place, making the current official forecast a low-confidence one.

Debby's place in history
Remarkably, Debby's formation on June 23 comes a full two months ahead of the usual formation date of the season's fourth storm in the Atlantic, August 23. Debby's formation beats by twelve days the previous record for formation of the fourth named storm of the year in the Atlantic, set in 2005, when Hurricane Dennis was named on July 5. An early start to the Atlantic hurricane season has been increasingly common in recent years. In 2008, I blogged about the research of Dr. Jim Kossin of the University of Wisconsin, who published a 2008 paper in Geophysical Research Letters, titled "Is the North Atlantic hurricane season getting longer?" He concluded that yes, there is a "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". Three out of four of this year's early quartet of storms--Alberto, Beryl, and Debby--formed in ocean areas that were more than 1°F above average, which is an unusually high amount of warmth. We should expect to see more early-season Atlantic tropical storms as a consequence of global warming, since cool ocean temperatures are a key impediment to formation of such storms. However, this assumes that factors such as wind shear and atmospheric stability won't grow more hostile for tropical cyclone formation during the early part of hurricane season, and this is uncertain. If we do end up seeing a substantial increase in early-season tropical storms as a consequence of global warming, this is not necessarily a bad thing. Early-season tropical storms are often more boon than bane, bringing much-needed drought-busting rains, like Tropical Storm Beryl did for North Florida last month. With drought frequency and intensity predicted to increase for much of the Gulf Coastal states in coming decades, an increase in rainfall from early-season tropical storms may do more good than the damages inflicted by the high winds and flooding these storms may bring. There is typically a lot of wind shear around in May, June, and July, making it difficult for early season storms to reach major hurricane status. According to Wunderground's list of major early-season hurricanes, since record keeping began in 1851, there has been only one major hurricane in May, two in June, and nine in July. Three of these occurred in the past ten years, so there has not as yet been an observable large increase in early-season major hurricanes due to global warming.

References
Kossin, J., 2008, "Is the North Atlantic hurricane season getting longer?", Geophysical Research Letters, Vol. 35, L23705, doi:10.1029/2008GL036012, 2008.

Record heat in Colorado
On Saturday, for the second consecutive day, record heat scorched Colorado. According to wunderground's weather historian Christopher C. Burt, the 104° reading in Denver tied for the hottest June temperature on record in the city, last set on June 26, 1994. It was also just 1° short of the all-time record of 105° (set on July 20, 2005 and August 8, 1878.)

Colorado Springs tied its all-time record for warmest temperature ever measured on Saturday, with 100°. The city has hit 100° four other times, most recently on July 24, 2003.

Pueblo, Co reached 106°, a daily record; this was just 2° shy of the monthly record of 108°. The all-time record is 109° on 7/13/2003.

Lamar, Co hit 109°, just 2° short of the all-time record of 111° set on 7/13/1934.

The Colorado heat did no favors for firefighters, who are struggling to the contain the massive 81,000 acre High Park fire fifteen miles northwest of Fort Collins. The fire is the second largest and most destructive wildfire in Colorado's history, and is 45% contained. A new fire erupted Saturday in Estes Park, at the boundary of Rocky Mountain National Park, and destroyed 21 homes.

Jeff Masters

Hurricane

Updated: 2:11 PM GMT on June 24, 2012

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Tropical Storm Debby has formed in the Gulf of Mexico

By: angelafritz , 9:18 PM GMT on June 23, 2012

Tropical Storm Debby has been named by the National Hurricane Center this afternoon after hurricane hunters investigated Invest 96L and found a solid closed circulation, with maximum winds of 50mph and gusts up to 65mph. All interests along the Gulf of Mexico coast should pay attention to the progress of Debby. Debby is drifting north at 5mph. The storm has brought heavy rains to Western Cuba, South Florida, and Mexico's Yucatan Peninsula over the past two days, but the disturbance's heaviest rains are located well offshore over the Eastern Gulf of Mexico, where heavy thunderstorms are generating winds near tropical storm-force. A buoy 243 miles west of Naples, FL measured sustained winds of 31 mph, gusting to 38 mph, with 10-foot waves, at 8 am EDT Saturday morning. Our Wundermap for the surrounding ocean areas shows a large region of the northern and eastern Gulf of Mexico is experiencing winds of 20 - 30 mph.

Visible satellite loops show an unorganized tropical cyclone with an obvious surface circulation, though the thunderstorm activity is well displaced to the east. The heavy thunderstorm activity is slowly expanding and growing more intense. Upper-level winds out of the west continue to create moderate 10 - 20 knots of wind shear over the region, though that is expected to increase over the next few days. Water vapor satellite loops show a region of dry air over the central Gulf of Mexico, which will continue to interfere with Debby's development and make it hard for the west side of the circulation to maintain heavy thunderstorms. Ocean temperatures are about 28.5°C (83°F) in the Central Gulf of Mexico, which is about 1°F above average.


Figure 1. Saturday afternoon satellite image of Tropical Storm Debby in the Gulf of Mexico.


Figure 2. Saturday afternoon forecast track for Tropical Storm Debby.

Forecast for Debby
The National Hurricane Center is forecasting Debby to remain a tropical cyclone over the next 5 days as it drifts north and then west toward Texas. The Hurricane Center is forecasting a very slow progression of the storm, with a potential landfall not occurring until Friday. However, most of the models that predict the turn to the west suggest landfall will happen before or around Wednesday. The models are still generally split on the forecast for Debby; by Monday, the majority of the reliable models, including the ECMWF, NOGAPS, HWRF, and UKMET, agree that a ridge of high pressure will build in over the Southern U.S., forcing Debby west across the Gulf of Mexico and into South Texas by Wednesday. However, the GFS model, which has been our 2nd most reliable track model over the past two years (behind the ECMWF), has consistently been predicting that a trough of low pressure pushing off of the U.S. East Coast will be capable of grabbing the disturbance and accelerating it to the northeast across Florida north of Tampa Bay on Monday. The GFDL model splits the difference between these extremes and takes Debby north to a landfall near the Alabama/Florida border on Tuesday. The predicted track west to Texas is still the most likely outcome, though it remains a low-confidence forecast. In terms of intensity, none of the models is predicting Debby will become a hurricane, nor is the Hurricane Center. Though sea surface temperature is warm (and around 1°F above average), the actual heat content of the Gulf is relatively low. Wind shear is predicted to remain moderately strong through Sunday, but will increase to 30+ knots by Tuesday.

Debby's place in history (by Jeff Masters)
Remarkably, Debby's formation on June 23 comes a full two months ahead of the usual formation date of the season's fourth storm in the Atlantic, August 23. Debby's formation beats by twelve days the previous record for formation of the fourth named storm of the year in the Atlantic, set in 2005, when Hurricane Dennis was named on July 5. An early start to the Atlantic hurricane season has been increasingly common in recent years. In 2008, I blogged about the research of Dr. Jim Kossin of the University of Wisconsin, who published a 2008 paper in Geophysical Research Letters, titled "Is the North Atlantic hurricane season getting longer?" He concluded that yes, there is a "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". Three out of four of this year's early quartet of storms--Alberto, Beryl, and Debby--formed in ocean areas that were more than 1°F above average, which is an unusually high amount of warmth. We should expect to see more early-season Atlantic tropical storms as a consequence of global warming, since cool ocean temperatures are a key impediment to formation of such storms. However, this assumes that factors such as wind shear and atmospheric stability won't grow more hostile for tropical cyclone formation during the early part of hurricane season, and this is uncertain. If we do end up seeing a substantial increase in early-season tropical storms as a consequence of global warming, this is not necessarily a bad thing. Early-season tropical storms are often more boon than bane, bringing much-needed drought-busting rains, like Tropical Storm Beryl did for North Florida last month. With drought frequency and intensity predicted to increase for much of the Gulf Coastal states in coming decades, an increase in rainfall from early-season tropical storms may do more good than the damages inflicted by the high winds and flooding these storms may bring. There is typically a lot of wind shear around in May, June, and July, making it difficult for early season storms to reach major hurricane status. According to Wunderground's list of major early-season hurricanes, since record keeping began in 1851, there has been only one major hurricane in May, two in June, and nine in July. Three of these occurred in the past ten years, so there has not as yet been a large increase in early-season major hurricanes due to global warming.

References
Kossin, J., 2008, "Is the North Atlantic hurricane season getting longer?", Geophysical Research Letters, Vol. 35, L23705, doi:10.1029/2008GL036012, 2008.

Angela and Jeff

Hurricane

Updated: 1:50 AM GMT on June 24, 2012

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Gulf of Mexico disturbance 96L close to tropical storm status

By: JeffMasters, 1:26 PM GMT on June 23, 2012

An area of low pressure and heavy thunderstorms in the Central Gulf of Mexico (96L) is close to tropical depression or tropical storm status, and all interests along the Gulf of Mexico coast should pay attention to the progress of this disturbance. The disturbance has brought heavy rains to Western Cuba, South Florida, and Mexico's Yucatan Peninsula over the past two days, but the disturbance's heaviest rains are located well offshore over the Eastern Gulf of Mexico, where heavy thunderstorms are generating winds near tropical storm-force. A buoy 243 miles east of Naples, FL measured sustained winds of 31 mph, gusting to 38 mph, with 10-foot waves, at 8 am EDT Saturday morning. Our wundermap for the surrounding ocean areas shows a large region of the northern and eastern Gulf of Mexico is experiencing winds of 20 - 30 mph. Satellite-based surface wind measurements taken at 7:22 am EDT Saturday from the newly-available Oceansat-2 scatterometer, courtesy of India, showed a broad, elongated surface circulation over the Central Gulf of Mexico that was not well defined. The satellite saw top surface winds of 30 - 40 mph over the Eastern Gulf of Mexico. Visible satellite loops show that the circulation of 96L has become more defined this morning, and the heavy thunderstorm activity is slowly expanding and growing more intense. Upper-level winds out of the west are creating a moderate 10 - 20 knots of wind shear over the region. Water vapor satellite loops show a modest region of dry air over the Central Gulf of Mexico, which is interfering with development and keeping the western side of 96L's circulation free of heavy thunderstorms. Ocean temperatures are about 28.5°C (83°F) in the Central Gulf of Mexico, which is about 1°F above average. A hurricane hunter mission is scheduled to investigate 96L this afternoon to see if a tropical depression or tropical storm has formed.


Figure 1. Saturday morning satellite image of tropical disturbance 96L in the Gulf of Mexico.


Figure 2. Radar-estimated precipitation for South Florida from tropical disturbance 96L.

Forecast for 96L
Wind shear is predicted to remain in the moderate range through Sunday night, which is likely low enough to allow 96L to develop into a tropical depression or tropical storm by Sunday; NHC gave 96L a 90% chance of developing into a tropical depression by Monday morning, in their 8am EDT Tropical Weather Outlook. The future path of 96L is still unclear. The disturbance will drift slowly northwards through Sunday night, which will likely bring heavy rains of 2 - 4 inches to the Gulf Coast from Central Louisiana to Central Florida. A storm surge of 1 - 3 feet is also likely along the Southeast Louisiana coast on Sunday; coastal flood advisories have already been posted there. By Monday, the majority of the reliable models, including the ECMWF, NOGAPS, HWRF, and UKMET, agree that a ridge of high pressure will build in over the Southern U.S., forcing 96L westwards across the Gulf of Mexico and into South Texas by Wednesday. However, the GFS model, which has been our 2nd most reliable track model over the past two years (behind the ECMWF), has consistently been predicting that a trough of low pressure pushing off of the U.S. East Coast will be capable of grabbing the disturbance and accelerating it to the northeast across Florida north of Tampa Bay on Monday. The GFDL model splits the difference between these extremes, taking 96L northwards to a landfall near the Alabama/Florida border on Tuesday. Given that the majority of the models predict a westward track to Texas, that should be viewed as the most probable path for 96L, but this is a low-confidence forecast. None of the models is predicting 96L will become a hurricane, and the SHIPS model is predicting just a 4% chance of rapid intensification for 96L. Given the moderate levels of wind shear and dry air over the Gulf, only slow to modest intensification of 96L is likely over the next few days.

Jeff Masters

Hurricane

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Gulf of Mexico disturbance 96L poorly organized, but may develop

By: JeffMasters, 2:27 PM GMT on June 22, 2012

An area of low pressure and heavy thunderstorms in the Southern Gulf of Mexico (designated 96L by NHC Thursday afternoon) is a threat to become a tropical depression this weekend, and all interests along the Gulf of Mexico coast should pay attention to the progress of this disturbance. The disturbance is bringing occasional heavy rains to Western Cuba, South Florida, and Mexico's Yucatan Peninsula. Top winds measured in the surrounding ocean areas this morning were 27 mph, gusting to 34 mph, at the Yucatan Basin buoy between Mexico's Yucatan Peninsula and the Cayman Islands. Our wundermap for the surrounding ocean areas show a ship that measured sustained winds of 30 mph near the western tip of Cuba this morning. Satellite-based surface wind measurements from the newly-available Oceansat-2 scatterometer, courtesy of India, show no signs of a surface circulation. Visible satellite loops show that 96L is less organized than it was Thursday evening, with only a little low-level spin apparent, and a modest area of disorganized thunderstorms. The decrease in organization is probably due to the moderate to high levels of wind shear of 15 - 25 knots over the region. Water vapor satellite loops show a modest region of dry air over the Central Gulf of Mexico, which is interfering with development. Ocean temperatures are 81 - 83°F in the Western Caribbean and Southern Gulf of Mexico, which is about 1°F above average, and warm enough to support formation of a tropical storm. A hurricane hunter mission is scheduled to investigate 96L this afternoon, but this mission will probably be cancelled due to the disturbance's lack of organization.


Figure 1. Morning satellite image of the tropical disturbance 96L in the Southern Gulf of Mexico.

Forecast for 96L
Wind shear is predicted to remain in the moderate range through Saturday night, which is likely low enough to allow 96L to develop into a tropical depression; NHC gave 96L a 70% chance of developing into a tropical depression by Sunday morning, in their 8am EDT Tropical Weather Outlook. By Sunday, wind shear is predicted to increase, limiting 96L's potential for intensification. Where the storm might go is anybody's guess. The GFS model has consistently been predicting that a trough of low pressure pushing off of the U.S. East Coast will be capable of grabbing the disturbance and accelerating it to the northeast across Florida north of Tampa Bay on Sunday or Monday. However, an ensemble of forecasts from the model created by running the model with slight perturbations to the initial conditions shows a wide range of possible tracks, both to the east over Florida, and to the west towards Texas and Louisiana (Figure 2.) The latest ECMWF model run (00 UTC) predicts that the trough will not be strong enough to pull 96L northeastwards across Florida. The ECMWF predicts that a ridge of high pressure will build in over the Southern U.S., forcing the disturbance westwards across the Gulf of Mexico and into South Texas by Thursday. The UKMET model also favors a track west towards Texas. The NOGAPS model takes 96L to the northwest into Louisiana/Texas by Monday.


Figure 2. Which way will 96L go? The GFS model, when run at low resolution with 20 slightly different perturbations to the initial conditions in order to generate an ensemble of different forecasts, shows two distinct possibilities: a sharp east turn to move over Florida, or a west or northwest motion towards Louisiana or Texas. The high-resolution official GFS forecast is shown in white.

Jeff Masters

Hurricane

Updated: 2:39 PM GMT on June 22, 2012

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Gulf of Mexico disturbance may develop; Chris a hurricane; record Duluth flooding

By: JeffMasters, 3:03 PM GMT on June 21, 2012

An area of low pressure and heavy thunderstorms entering the Southern Gulf of Mexico is bringing sporadic heavy rains to Western Cuba and Mexico's Yucatan Peninsula, and winds of 20 - 25 mph to surrounding ocean areas. This disturbance will need to be watched for development as it drifts slowly northward at about 5 mph into the Central Gulf of Mexico by Saturday. The disturbance is poorly organized, and has only a modest area of heavy thunderstorms. Wind shear is a moderate to high 15 - 25 knots over the region. Ocean temperatures are 81 - 83°F in the Western Caribbean and Southern Gulf of Mexico, which is about 1°F above average, and plenty warm to support formation of a tropical storm.


Figure 1. Morning satellite image of the tropical disturbance entering the Southern Gulf of Mexico.

Forecast for Gulf of Mexico disturbance
Wind shear is predicted to remain in the moderate to high range through Friday. Water vapor satellite loops show a region of dry air over the Northern Gulf of Mexico; this dry air is probably too far away to significantly interfere with development. I expect we will see an increase in the disturbance's heavy thunderstorm activity today as a result of less interference from dry air. By Saturday, our two top models, the European model (ECMWF) and GFS, predict that wind shear could fall to the moderate range, 10 - 20 knots, which would potentially allow the disturbance to approach tropical depression status by Sunday. A trough of low pressure pushing off of the U.S. East Coast will be capable of grabbing the disturbance and accelerating it to the northeast on Sunday, as predicted by the GFS model, which takes the disturbance across Florida on Sunday, and into the waters off the coast of South Carolina by Monday. The GFS does not develop the disturbance while it is in the Gulf of Mexico, but suggests it could develop into a tropical or subtropical depression off the coast of South Carolina Monday or Tuesday. The latest ECMWF model run (00 UTC) predicts that this through will not be strong enough to pull the disturbance northeastwards across Florida, and the disturbance will instead linger in the Gulf of Mexico for many days, giving it time to develop into a tropical depression next week. The UKMET and NOGAPS models predict a more westward drift, with the disturbance affecting the Mexico/Texas border region 6 - 7 days from now. At this point, we can't rule out any location in the Gulf being affected by this system, though the Gulf coast of Florida has the highest probability of seeing impacts. NHC is giving the disturbance a 30% chance of developing into a tropical depression by Saturday morning. This is a reasonable forecast, and the odds will probably rise by Friday, and I give the disturbance a 50% chance of developing into a tropical depression by Monday morning.


Figure 2. Morning satellite image of Hurricane Chris.

Chris reaches hurricane strength; not a threat to land
Hurricane Chris has managed to intensify and form an eye-like feature surrounded by intense thunderstorms with very cold tops, despite the fact the storm is over cool waters of 22°C. NHC puts Chris at hurricane strength with 75 mph winds making it the first hurricane of the 2012 hurricane season. Chris attained hurricane strength unusually far to the north (41.1°N) for a June storm; only Hurricane One of 1893 was a June hurricane at a more northernly point (44°N) than Chris. Chris is headed northeastwards, out to sea, and will not trouble any land areas. Only twice before, in 1887 and 1959, has the third storm of the season formed earlier than June 20. Formation of three tropical storms so early in the year is not necessarily a harbinger of an active season; 1959 was close to average, with 12 named storms, 7 hurricanes, and 2 intense hurricanes (average is 11 named storms, 6 hurricanes, and 2 intense hurricanes.) Unusual levels of early season activity in the Caribbean and between Africa and the Lesser Antilles usually portends a very active hurricane season, but this year's storms have not formed in this region. Alberto, Beryl, and Chris all formed off the U.S. East Coast.


Figure 3. The St. Louis river upstream from Duluth, Minnesota reached its highest flood height on record this morning, 6.1' above flood stage. The river rose over ten feet in 24 hours. Image credit: NOAA.

Record flooding in Duluth, Minnesota
Flood waters have crested in Duluth, Minnesota this Thursday morning, and are slowly falling, in the wake of the city's all-time record 24-hour rainstorm. A series of "training" thunderstorms that followed the same path passed over a wide swath of Northern Minnesota between noon Tuesday and noon Wednesday, dropping 7.20" of rain on the city. According to wunderground's weather historian Christopher C. Burt, this far surpasses the previous 24-hour record rainfall for Duluth, the 5.79" that fell on August 22 - 23, 1978. Two rivers in the Duluth area, the Nemadji and St. Louis, hit their highest flood heights on record Thursday morning, causing destructive flooding. Sadly, major flooding occurred at the Duluth zoo, washing a seal into a neighboring street, and killing at least eleven zoo animals.

Jeff Masters

Hurricane Flood

Updated: 2:38 PM GMT on June 22, 2012

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Tropical Storm Chris forms; little change to Cuba disturbance; Duluth floods

By: JeffMasters, 1:33 PM GMT on June 20, 2012

Tropical Storm Chris formed Tuesday evening from a extratropical storm that spent enough time over waters of 24 - 26°C to acquire tropical characteristics. Chris is headed eastwards, out to sea, and will not trouble any land areas. Only twice before, in 1887 and 1959, has the third storm of the season formed earlier than this date. Formation of three tropical storms so early in the year is not necessarily a harbinger of an active season; 1959 was close to average, with 12 named storms, 7 hurricanes, and 2 intense hurricanes (average is 11 named storms, 6 hurricanes, and 2 intense hurricanes.) Unusual levels of early season activity in the Caribbean and between Africa and the Lesser Antilles usually portends a very active hurricane season, but this year's storms have not formed in this region. Alberto, Beryl, and Chris all formed off the U.S. East Coast.


Figure 1. Morning satellite image of Chris.

Disturbance near Cuba will bring heavy rains to Florida
An area of low pressure and heavy thunderstorms centered just south of Cuba has changed little since Tuesday, and is bringing sporadic heavy rains to Jamaica, the Cayman Islands, South Florida, the Southern Bahamas, and Cuba. This disturbance will need to be watched for development as it drifts slowly northwest at about 5 mph and enters the Gulf of Mexico late this week. The disturbance is poorly organized, and has only a modest area of heavy thunderstorms. Wind shear is a moderate to high 15 - 25 knots over the region, and the shear is predicted to remain in the moderate to high range for the next three days along the disturbance's path. Water vapor satellite loops show a region of dry air over the Southern Gulf of Mexico; strong upper-level winds out of the northwest are bringing some of this dry air into the vicinity of the disturbance, which is interfering with development. NHC is giving the disturbance a 20% chance of developing into a tropical depression by Friday morning. As the disturbance reaches the waters off the southwest coast of Florida this weekend, a strong trough of low pressure pushing off of the U.S. East Coast will be capable of grabbing the storm and accelerating it to the northeast. This is the solution of the GFS model, which takes the storm across Florida on Sunday, and into the waters off the coast of South Carolina by Monday, with the disturbance developing into a tropical or subtropical storm off the coast of South Carolina. None of the other reliable computer models is showing development of the disturbance into a tropical depression. I think it is unlikely that heavy rains from this disturbance will affect Louisiana and Texas, but it will bring heavy rains to Southwest Florida and Cuba over the next five days.


Figure 2. Morning satellite image of the tropical disturbance near Cuba.


Figure 3. Rainfall for the 5-day period ending at 8am EDT Monday as predicted by NOAA's Hydrometeorological Prediction Center. Amounts in excess of five inches (orange colors) are predicted for Southwest Florida, with an area of ten inches (yellow colors) just off the coast.

Major flooding in Duluth, Minnesota
A serious flood emergency is occurring in Duluth, Minnesota. A series of "training" thunderstorms that all passed over the same region have dumped 4 - 5 inches of rain over a wide swath of Northern Minnesota overnight and early this morning. Nearly 8 inches of rain fell in the Denfeld area of western Duluth. This is more rain than fell in the city's previous worst flood on record, which occurred August 20, 1972. Major flooding is occurring, and only emergency travel is recommended in the city due to flooded roads. A flash flood warning from the Duluth National Weather Service issued at 7am CDT said this:

We cannot stress what a major threat this is for the city of Duluth
and along the North Shore. Aging infrastructure will also play a
part in the flood threat... especially on the hillside. Highway 61
remains closed in spots with washouts... overflowing streams and
rivers...washed out culverts and washed out roads. Just because you
might be able to travel to a destination now... does not mean you
will make it in one to two hours. This is how fast this situation
may deteriorate as more rainfall moves in from the west. There is
the potential for several more inches of rain today and the utility
system and the saturated ground cannot take much more rain.


According to wunderground's weather historian, Christopher C. Burt, the all-time 24 hour precipitation record for Duluth is 5.79" on 8/22 - 8/23 1978; 4.14" was recorded on Tuesday at the airport.


Figure 4. Radar-estimated rainfall from the Duluth, Minnesota radar.

Jeff Masters

Hurricane Flood

Updated: 2:43 PM GMT on June 20, 2012

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Two Atlantic disturbances to watch; Guchol hits Japan; extreme heat in Colorado

By: JeffMasters, 2:55 PM GMT on June 19, 2012

An area of low pressure and heavy thunderstorms has developed over Western and Central Caribbean, and this disturbance will need to be watched for development as it moves northwest at 5 - 10 mph and enters the Gulf of Mexico late this week. The disturbance is poorly organized, and its modest area of heavy thunderstorms is bringing rains to Jamaica, the Cayman Islands, South Florida, the Southern Bahamas, and Cuba today. Wind shear is a moderate to high 20 - 30 knots over the region, and the shear is predicted to remain in the moderate to high range for the next three days along the disturbance's path. Water vapor satellite loops show a region of dry air over the Southern Gulf of Mexico and Yucatan Peninsula; strong upper-level winds out of the southwest are bringing some of this dry air into the vicinity of the disturbance, which is interfering with development. NHC is giving the disturbance a 10% chance of developing into a tropical depression by Thursday morning. None of the computer models is showing development of the disturbance into a tropical depression, but I wouldn't be surprised to see the system grow in size and potential for development over the next few days. There are currently no hurricane hunter missions scheduled to investigate.


Figure 1. Morning satellite image of the tropical disturbance near Cuba.

North Atlantic Invest 95L headed out to sea
A well-organized low pressure system with a closed surface circulation but little heavy thunderstorm activity (Invest 95L) is over the open Atlantic between Bermuda and Canada. This storm doesn't have enough heavy thunderstorms to deserve a name, but has a 50% chance of doing so before hitting colder waters on Wednesday, according to NHC. 95L is headed northeast out to sea, and will not trouble any land areas.


Figure 2. Tropical Storm Guchol as seen from NASA's Aqua satellite on June 19, 2012, as the storm approached Japan. Image credit: NASA.

Tropical Storm Guchol hits Japan
Tropical Storm Guchol made landfall in Japan's southern Wakayama prefecture near 9 UTC Tuesday morning. The Japan Times reports that the storm has injured five people, and 83,000 people have been evacuated. Guchol is the first June tropical cyclone to hit Japan since 2004. Tokyo recorded sustained winds of 56 mph, gusting to 76 mph, at 10:47pm local time (9:47 am EDT.) A wind gust of 74 mph was recorded at Shizuhama at 8:21 pm local time. The main threat from Guchol is heavy rain. The storm is expected to dump rains in excess of 400 mm (15.7") in the Tokai region, and 250 mm (9.8") inches near Tokyo. Japan is also watching Tropical Storm Talim, which is expected to pass along the length of the country Thursday and Friday. Talim's rains could cause considerable trouble, as they will fall on soils already saturated by the passage of Tropical Storm Guchol.

Intense heat in Colorado
One of the warmest days in Eastern Colorado history was observed Monday. According to wunderground's weather historian Christopher C. Burt, Denver had a daily record high of 100°F, but Wray, near the Kansas-Nebraska border, reached 109°. This was just short of its all-time record (for any month) of 110°F set in July 1934, and just 5° shy of the all-time state of Colorado record of 114°F set at Las Animas and Sedgwick on July 25, 1952. Lamar in Southeast Colorado hit 108°F yesterday, just 3° short of its all-time record of 111°F set in July 1934. Sterling, the in the far Northeast part of the state, hit 108°F, which may be its all-time heat record. The intense heat yesterday was accompanied by some very dry air. The humidity in Broomfield, CO fell to 4% for more than six hours on Monday. The hot, dry weather made firefighting efforts difficult for the massive wildfire burning 15 miles west of Fort Collins, CO. This fire is the third largest and most destructive fire in Colorado history. Firefighters have achieved 50% containment of the blaze.

Jeff Masters

Hurricane Heat

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Typhoon Guchol approaches southern Japan; 95L no threat to U.S.

By: angelafritz , 7:45 PM GMT on June 18, 2012

Typhoon Guchol is a category 2 on the Saffir-Simpson scale, with winds of 110 mph, gusting to 130mph. Guchol is on a path to southern Japan, where it is expected to make landfall Tuesday evening. The typhoon is moving north-northeast at 20 mph, and has been weakening, a trend that the Joint Typhoon Warning Center thinks will continue. Guchol's eye is completely clouded over, and the heavy thunderstorms on the west side of the typhoon have weakened, possibly due to an increase in wind shear from the west. Both Guchol and Talim, a tropical storm in the South China Sea, are drenched in tropical moisture. The elements that prevent Guchol from maintaining its strength are increasing wind shear and decreasing sea surface temperature.


Figure 1. High resolution, true color satellite imagery from MODIS of Typhoon Guchol captured today, June 18th, at 12:45 am EDT.

Forecast for Guchol
Guchol is forecast to weaken further as it continues its track northeast toward Japan. Sea surface temperature will decrease as the typhoon moves north out of favorable water, and wind shear is expected to continue to increase. Guchol will probably start to become non-tropical as it makes landfall near Kyoto. However, tropical storm conditions, heavy rain and gusty winds will likely affect a large portion of Japan through Wednesday. The Japan Meteorological Agency forecasts that up to 16 inches of rain (40 cm) is possible from Guchol, and so flash flooding and landslides are a potential hazard from the storm.

North Atlantic Invest 95L

An area of thunderstorms in the North Atlantic now has a 50% chance of becoming a tropical cyclone, according to the National Hurricane Center. 95L originally spun up as a non-tropical disturbance, but is starting to gain tropical characteristics. It's possible that, if 95L gains enough strength, it will be characterized as subtropical. This system poses no threat to the U.S. or Canada—models agree that 95L will track east away from North America, and will likely remain weak should it develop.


Figure 2. North Atlantic invest 95L as of 2pm EDT on June 18th.

Angela

Hurricane

Updated: 7:47 PM GMT on June 18, 2012

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Damages from June 13 hailstorm in Dallas may be $2 billion

By: JeffMasters, 4:31 PM GMT on June 17, 2012

Insured damage from a massive 3-hour hailstorm that pummeled Dallas, Texas on Wednesday, June 13, may reach $2 billion, said the Southwestern Insurance Information Service (SIIS) on Friday. If true, this would be the fourth billion-dollar U.S. weather disaster of 2012. A cluster of three severe thunderstorms dropped hail the size of baseballs over a heavily populated area, damaging thousands of cars, puncturing skylights at a local mall, and shattering the expensive tile roofs of hundreds of homes. It was the second major hailstorm to hit the region this year; an April 3 event cost close to $500 million, and damaged 110 airplanes at the DFW airport. You can see a radar image of the June 13 storm using our wundermap with the "go back in time" feature turned on.


Figure 1. Huge hail splashes into the waters of White Rock Lake in Dallas on June 13, 2012. Image credit: Wunderphotographer CinnamonDreams.

One of the most expensive hailstorms of all-time
The June 13 hailstorm will rank as one of the most expensive of all-time, according to statistics of billion-dollar disasters maintained by NOAA's National Climatic Data Center (NCDC), and a list of damaging hail events maintained at Wikipedia. Wikipedia lists only three hailstorms in U.S. history with damages exceeding $1 billion:

1) The April 10, 2001 St. Louis, Missouri hailstorm. This costliest hailstorm in U.S. history, costing $2+ billion, struck the I-70 corridor of eastern Kansas, across Missouri, into southwestern Illinois.

2) The May 5, 1995 Mayfest Storm in Dallas and Fort Worth, Texas. Severe thunderstorms produced hail the size of softballs, causing $1.1 billion in insured losses, and total damage of $2 billion.

3) The July 11, 1990 hailstorm in Colorado. Softball-sized hail destroyed roofs and cars, causing $625 million in total damage ($1.1 billion in damage adjusted to 2011 dollars.)


Video 1. News coverage of the June 13, 2012 hailstorm in Dallas, Texas, from local TV station News8. The aerial shots of a fog-shrouded golf course covered with ice are quite remarkable.

Six global billion-dollar weather disasters so far in 2012
There have been five global billion-dollar weather disasters as of the end of May, said Aon Benfield in their latest May Catastrophe Recap. Three of these were in the U.S. With the addition of the June 13 Dallas hailstorm, the global total would rise to six and the U.S. total to four. The most expensive weather-related disaster of 2012 has been the March 2 - 3 tornado and severe weather outbreak in the Midwest and Southeast U.S., which killed 41 people and caused $3 billion in damage. The second most expensive was the severe thunderstorms and heavy rains that hit China during late April and early May, bringing flooding, landslides, and damaging hail to the Gansu, Hunan and Jiangxi provinces. Over 143,000 homes were damaged or destroyed, with $2.68 billion in damage. Two other severe weather outbreaks in the U.S. topped the $1 billion mark in damages in 2012: the April 27 - 29 event in the Midwest ($1.5 billion in damage), and an April 2 - 4 severe weather outbreak in Texas that did a tremendous amount of hail damage near Dallas/Ft. Worth ($1 billion.) A fourth severe weather event, April 13 - 15 in the Plains and Midwest, is very close the $1 billion mark ($950 million in damage.) Another weather disasters that might approach the $1 billion mark is the frosts and freezes that decimated Midwest fruit trees after 2012's "summer in March" heat wave. Agricultural damage in Michigan alone has been estimated by the state to be $223.5 million--including $130 million to cherry and apple orchards. The pace and cost of billion-dollar weather disasters in 2012 is well below that of 2011, which had had fourteen billion-dollar weather disasters between January and May (nine in the U.S.) These 2011 disasters cost $73 billion, compared to the $10 billion price tag of 2012's five-billion dollar disasters from January - May.



Super Typhoon Guchol headed towards Tokyo
Super Typhoon Guchol , a powerful Category 4 storm with 150 mph winds, is churning through the Western Pacific towards Japan, and is expected to pass close to Tokyo late Tuesday night local time. As Guchol approaches Japan on Monday and Tuesday morning, ocean temperatures will cool below 26°C and wind shear will increase, which should cause significant weakening of the typhoon. By the time of closest approach to Tokyo, I expect Guchol will most likely be a tropical storm, but could be a Category 1 typhoon.

The Atlantic is quiet
There are no threat areas to discuss in the Atlantic today. Several models are predicting that a tropical disturbance capable of becoming a tropical depression could form in Mexico's Bay of Campeche sometime June 22 - 24.

I'll have a new post late Monday or early Tuesday. Wunderground weather historian Christopher C. Burt has a post on record hailstorms.

Jeff Masters

Extreme Weather Severe Weather

Updated: 1:39 AM GMT on June 18, 2012

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Category 1 Hurricane Carlotta hits Mexico

By: JeffMasters, 4:30 PM GMT on June 16, 2012

Hurricane Carlotta made landfall near Escondido, Mexico Friday night at 8 pm PDT as a Category 1 hurricane with 90 mph winds. Carlotta moved inland over the rugged terrain of Mexico this morning, and has weakened to a tropical depression. Since Carlotta was a relatively small hurricane, strong winds affected only a small portion of the coast, and wind damage was probably fairly limited. However, the hurricane has dumped heavy rains along the coast to the east of Acapulco, and two deaths from a landslide triggered by heavy rains occurred this morning in the Oaxaca state community of Pluma Hidalgo. Carlotta will continue to dump heavy rains along the coast to the east of Acapulco, and the 4 - 8 inches of total rainfall that will occur in some areas will be capable of causing more life-threatening flash floods and landslides through the weekend.


Figure 1. Radar image of Carlotta from the Puerto Ánoel radar shortly before the storm made landfall.

The Atlantic is quiet
There are no threat areas to discuss in the Atlantic today. Several models are predicting that a tropical disturbance capable of becoming a tropical depression could form in Mexico's Bay of Campeche sometime June 22 - 24.

Have a great weekend, everyone!

Jeff Masters

Hurricane

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Hurricane Carlotta bears down on Mexico's Pacific coast

By: JeffMasters, 4:10 PM GMT on June 15, 2012

Hurricane Carlotta has steadily intensified today as it heads northwest towards the Mexican coast east of Acapulco. Recent satellite loops show a well-organized storm with a prominent eye, solid eyewall with cold cloud-tops, and good low-level spiral banding. Carlotta may be undergoing rapid intensification, thanks to favorable sea surface temperatures near 30°C (86°F) and moderate wind shear of 10 - 20 knots. A hurricane hunter mission is en-route, and will arrive at the storm near 2pm EDT on Friday to see how strong Carlotta has become. Carlotta's rain bands have already moved over the coast of Mexico a few hundred miles east of Acapulco, as seen on Puerto Ánoel radar.


Figure 1. Morning satellite image of Carlotta.


Figure 2. Morning radar image of Carlotta from the Puerto Ánoel radar.

Forecast for Carlotta
Carlotta is likely to continue to strengthen as it approaches the western coast of Mexico east of Acapulco. As a large portion of the hurricane's circulation moves over the mountains of Mexico on Saturday morning, steady weakening should occur. Heavy rains from Carlotta will be the storm's main threat, and these rains will steadily progress westwards along the coast, arriving at Acapulco by Saturday morning. With rainfall amounts of 6 - 10 inches possible along the track of Carlotta, the potential for dangerous flash flooding and mudslide will be a concern all along the coast affected by Carlotta.

The Atlantic is quiet
There are no threat areas to discuss in the Atlantic today. The GFS model is predicting that some of the moisture and energy from Carlotta could move into the Gulf of Mexico next week and form a tropical disturbance capable of becoming a tropical depression, but this solution is unlikely.

Jeff Masters

Hurricane

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Tropical Storm Carlotta forms in the East Pacific

By: angelafritz , 5:25 PM GMT on June 14, 2012

Tropical Storm Carlotta has formed in the East Pacific, and is heading northwest toward the west coast of Mexico, where impacts are expected to begin on Friday. Carlotta has maximum sustained winds of 45 mph gusting to 55 mph. A hurricane hunter mission is tentatively scheduled for 2pm EDT on Friday. Carlotta's rain is visible on Puerto Ánoel's radar this afternoon. The storm appears to be well-vented, with high-level outflow apparent on satellite, and thunderstorms firing on all sides of the storm's center. The storm is currently in an area of low wind shear, however, shear will likely increase as the storm moves north. Sea surface temperature under Carlotta is slightly above average—around 30°C (86°F)—and is expected to remain around there for the next few days. These conditions are favorable for strengthening. Tropical Storm Carlotta is the 3rd tropical cyclone and named storm in the basin, and is the 5th earliest formation of the season's 3rd storm. The earliest 3rd storm formation on record is June 7th: a record tied by Hurricane Connie of 1974 and Tropical Storm Carlos of 1985.


Visible satellite image of Tropical Storm Carlotta taken at 11am EDT on Thursday.

Forecast for Carlotta
Tropical Storm Carlotta is expected to continue on its path northwest over the next few days, as it approaches the western coast of Mexico, near Acapulco. Most of the reliable track models agree with this (GFS, GFDL, HWRF, UKMET). The GFS ensemble members are basically in agreement with NHC track, however, some ensembles are still suggesting that Carlotta's energy could jump the gap and transfer into the Gulf of Mexico early next week, which is an unlikely solution. The National Hurricane Center is forecasting Carlotta to reach hurricane status on Friday. This intensification, though quick, will be short-lived as the cyclone interacts with land. Granted, the intensity of this system depends heavily on how close to the coast it gets. The mountains of western Mexico can tear apart a tropical storm or weak hurricane with ease. In any case, Carlotta is expected to bring heavy rain to an area prone to flash flooding and landslides.

Meanwhile, in the Atlantic
No tropical cyclone activity is expected in the next couple of days, though some models are suggesting an easterly wave could develop into a weak tropical cyclone in the western Caribbean or southern Gulf of Mexico next week.

Angela

Hurricane

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Wildfire smoke shrouds Denver; climate change expected to increase Western fires

By: JeffMasters, 2:16 PM GMT on June 13, 2012

Colorado's third largest fire in recorded history, the High Park Fire, shrouded Denver and Fort Collins in acrid smoke Tuesday, causing an increase in emergency room visits related to smoke inhalation. The fire, currently burning fifteen miles west of Fort Collins, Colorado, covered over 43,000 acres (68 square miles) as of Tuesday. Firefighters reported that it was only 10% contained, and was exhibiting "extreme" behavior. A lightning strike triggered the fire on Saturday. While fire fighters try to control the southern edge of the fire, the northern perimeter is burning out of control. Six hundred eighty people and 100 fire engines are working on the ground to contain the blaze, along with air support from air tankers and helicopters. The fire has killed one person, burned 100 structures, and cost $1.6 million to fight so far. An air pollution action day has been declared for Wednesday all along the Front Range of the Rockies, from Denver to Fort Collins, due to smoke from the fire. Air pollution levels from smoke will be unhealthy for sensitive groups.


Figure 1. Fire burns in trees behind homes in the High Park wildfire near Fort Collins, Colorado, on Monday, June 11, 2012. (AP Photo)

Beetles, climate change, and Colorado fires
According to the Denver Post, the High Park Fire is burning in an area where 70% of the trees that have been killed by mountain pine beetles; the insects have devastated forests in western North America in recent years. As our climate change blogger, Dr. Ricky Rood explains, the pine beetle is killed (controlled) by temperatures less than -40°F. This is at the edge of the coldest temperatures normally seen in the U.S., and these cold extremes have largely disappeared since 1990. In Colorado, the lack of -40°F temperatures in winter has allowed the beetles to produce two broods of young per year, instead of one. The beetles are also attacking the pine trees up to a month earlier than the historic norm.


Figure 2. The historical mountain pine beetle (MPB) univoltine life cycle (above calendar arrows and linked by black arrows) and the observed MPB bivoltine life cycle (below calendar arrows and linked by red arrows). Univoltine means one brood per year, and bivoltine means two broods per year. Calendar arrow colors represent monthly temperature regimes: blue for less than 0°C, yellow for 0°-4.99°C, orange for 5°-9.99°C, and red for 10°C and higher. From Mitton and Ferrenberg, "Mountain Pine Beetle Develops an Unprecedented Summer Generation in Response to Climate Warming". This figure appeared in Dr. Ricky Rood's blog, "A Hot Day's Night: The Beetles".

A letter from the field in Colorado
Our climate change blogger, Dr. Ricky Rood, is in Boulder, Colorado this summer, and had this report on the fire Tuesday:

Saturday morning Iz and I were driving along 95th Street to Longmont to the Fairgrounds. We saw the initial plume; Iz said, "Looks like a volcano." At that time it was Colorado clear, with blue skies. The plume got to the top of its ascent and kicked off a little convection that looked like cauliflower. For the next few hours you could see the fire grow by the trunk of the plume getting thicker. It mostly blew to the east, with an occasional white cloud topping. It seemed to double in size every couple of hours.

By Sunday, the smoke was spreading all over the state. We had a couple of cool days with a northerly component in the wind. It filled up the sky, here, with haze - most of the day could not see Long's Peak. Part of the day couldn't see the foothills, say Flagstaff Mountain, which is about 8 miles away. Even with the wind moving around to the south, it's remained hazy. Today it has smelt of campfire-like smoke most of the day. Woke up sneezing. There is fine dust drawn to my computer screen and key board, which is at this point simply dirty. The dogs seem a little crazy.

It's not as acrid as the much closer Fourmile Fire a couple of years ago, but for some reason, it's the most dramatic fire I have experienced, perhaps because of the explosive nature of it. Tankers and helicopters fly over all day; they must stage from somewhere south of here. The tanks on them look hopelessly small compared with the fire, but they say, today, they finally made progress. The drought or drought potential is currently stunning, and we expect a lot of fire this year. Water only flowed in our irrigation ditch for four days before we lost priority.

There is a very nice figure in a local magazine, YS, that shows the percentage of snow pack compared with normal. We are South Platte - mid-May at 19 % normal, and not the worst in the state. Really, a nice little article in YS about how to predict a drought. Last year was nearly record wet. Right now this is setting up to be worse than the 2002 drought, which the article says was a 300 year drought. If true, then we had two 300 year droughts 10 years apart--some of our readers should be able to work on that as an attribution problem. The largest fire in Colorado history, the Hayman, was during the 2002 drought.


New Mexico's massive Whitewater Baldy Complex fire continues
The largest wildfire in New Mexico recorded history, the Whitewater Baldy Complex, continues to burn in the Gila National Forest. The lightning-sparked fire began nearly a month ago on May 15th, is 37% contained, and has devoured almost 280,000 acres (438 square miles.) Though fire weather advisories are not in effect in the region, the humidity is extremely low--humidity values of 6% were reported yesterday afternoon in Reserve, New Mexico, inside the burned area. Afternoon winds are expected to remain moderately strong, around 15 mph, over the next few days, as firefighters focus on keeping the southern edge of the fire from spreading. The fire has cost $22.6 million to fight so far.


Figure 3. The Whitewater Baldy Complex fire seen on our wundermap with the fire layer turned on. The red region outlined in yellow is the active fire perimeter.


Western U.S. wildfires expected to increase due to climate change
Expect a large increase in fires over much of the globe late this century due to climate change, says research published this month in the Journal Ecosphere. Using fire models driven by output from sixteen climate models used in the 2007 IPCC report, the researchers, led by Max Moritz of UC Berkeley, found that 38% of the planet should see increases in fire activity over the next 30 years. This figure increases to 62% by the end of the century. However, in many regions where precipitation is expected to increase--particularly in the tropics--there should be decreased fire activity. The scientists predicted that 8% of Earth will see decreases in fire probability over the next 30 years, and 20% will see decreases by the end of the century. The models do not agree on how fire danger will change for a large portion of the planet--54% for the period 2010 - 2039, and 18% for the period 2070 - 2099. Six key factors were found to control fire probabilities in the models. Most important was how much vegetation there was (NPP, Net Primary Productivity). Three other factors, about half as important, were precipitation of driest month, mean temperature of warmest month, and the difference between summer and winter temperature. Two other minor factors were mean temperature of wettest month, and annual precipitation. The authors found that future fire occurrence appears to primarily be a function of available moisture in many areas, and that the expected global increase in temperature of 3.5°C used in the models will not become the single dominant control on global wildfire. In the U.S., the regions most at risk of increased fires are the tundra regions of northern Alaska, and the West, with Arizona and Colorado at particularly high risk.


Figure 4. Predicted fractional change in fire probability for the period 2010 - 2039 (top) and 2070 - 2099 (bottom) for the average of sixteen climate models used for the 2007 IPCC report. For the 2010 - 2039 period, the models agree that 8% of Earth will see decreases in fire probability, 38% will see increases, and the models are too uncertain to tell for the other 54%. For the 2070 - 2099 period, the models agree that 20% of Earth will see decreases in fire probability, 62% will see increases, and the models are too uncertain to tell for the other 18%. Image credit: Climate change and disruptions to global fire activity, Moritz et al., 2012, from the journal Ecosphere.

Rare tornado hits Venice, Italy
A tornado hit Sant'Erasmo island in the lagoon surrounding Venice on Tuesday, ripping the roofs off of at least 12 buildings. No injuries were reported. The Capital Weather Gang has more videos and information on the event. Tornadoes are not unheard of in Venice; a strong one hit the city in 1970, killing 30 people.


Video 1. A waterspout/tornado in the Venice Lagoon on June 12, 2012.

The Atlantic is quiet
There are no threat areas to discuss in the Atlantic today. The NOGAPS and GFS models are predicting formation of a broad area of low pressure in the Western Caribbean early next week, and we will have to watch this area for development. The waters offshore of North Carolina may be another region to watch, over the next few days, along the edge of a cold front that has moved off the U.S. East Coast.

I'll have a new post Thursday or Friday.

Jeff Masters and Angela Fritz

Climate Change Fire

Updated: 2:26 PM GMT on June 13, 2012

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North Carolina ignores science in sea level planning

By: JeffMasters, 12:48 PM GMT on June 12, 2012

An interesting political battle is underway in North Carolina on how to plan for 21st century sea level rise, newsobserver.com reports. Sea level rise scientists commonly cite one meter (3.3 feet) as the expected global sea level rise by 2100, and more than a dozen science panels from coastal states, including a state-appointed science panel in North Carolina, agree. However, a coastal economic development group called NC-20, named for the 20 coastal counties in North Carolina, attacked the report, saying the science was flawed. NC-20 says the state should rely only on historical trends of sea level rise, and not plan for a future where sea level rise might accelerate. North Carolina should plan for only 8 inches of rise by 2100, based on the historical trend in Wilmington, NC, the group says. Republican state legislators introduced a bill that follows this logic, requiring the North Carolina Coastal Resources Commission to make development plans assuming sea level rise will not accelerate. On Thursday, a state senate committee signed off on the bill, sending it to the full Senate. NC-20 also successfully made an "intense push" to get the North Carolina Division of Emergency Management, which is using a $5 million federal grant to analyze the impact of rising water, to lower its worst-case sea level rise scenario from 1 meter (39 inches) to 15 inches by 2100.


FIgure 1. Global sea level rise from 1992 - April 2012, as measured by three satellite instruments (TOPEX, Jason-1, and Jason-2.) Sea level rise has been relatively constant at about 3.1 mm per year (1.2 inches per decade) during this time period. The big downward dip during 2010 is due to the fact that year had a record amount of precipitation over land areas. By 2011, that precipitation had run-off into the oceans, bringing sea level back up again. Image credit: University of Colorado Sea Level Research Group.

Commentary
East Carolina University geologist Stan Riggs, a science panel member and coastal science expert, said of the proposed legislation, “We’re throwing this science out completely, and what’s proposed is just crazy for a state that used to be a leader in marine science. You can’t legislate the ocean, and you can’t legislate storms.” Our climate change blogger, Dr. Ricky Rood, had this to say in his latest post: "I would dismiss the proposed law as an attempt to legislate away that which stands in the way of our desires to consume and build for our personal imperatives. I would dismiss it as politics and note the names of the un-serious politicians for the next election." I agree with both of these assessments. The best science we have argues the planet will continue to warm, melting icecaps, causing accelerated sea level rise. Between 1900 - 2007, global sea level rose at 1.7 mm per year (Bindoff et al., 2007). Between 1993 - 2012, sea level rise accelerated to 3.1 mm per year, a 75% increase over the 20th century rate. If this accelerated rate continues to 2100, global sea level rise will be 10.7", which is higher than the 8" rise North Carolina is being told to plan for. The continuing accelerating trend in Greenland ice loss since 2000 I blogged about last month should make anyone leery of betting that sea level rise will not accelerate even more in the coming decades. Betting that sea level rise won't accelerate this century is like betting that a slowly intensifying tropical storm will maintain that slow rate of intensification, ignoring that the majority of the computer models are predicting the storm will rapidly intensify into a Category 3 hurricane at landfall. Sure, sometimes the models are wrong, but there is good science behind their predictions. If we wait until storm begins its rapid intensification to act, it will be a very costly mistake. The most sound action would be to prepare for the very plausible bad outcome our science is saying is most likely, instead of putting all of our chips on the low-probability, good-for-business outcome we hope for.

Sea, No Evil
Comedian Steven Cobert has a humorous piece on the new North Carolina sea level legislation in his June 4, 2012 Cobert Report. He uses the phrase "Sea, No Evil" to describe the affair. Some quotes:

"It would be a tragedy to lose precious coastal wildlife habitats to coastal flooding. Those habitats should be lost to developers' bulldozers."

"If your science gives you a result that you don't like, pass a law that the result is illegal--problem solved!"

Comedy Central reports on the recent decision by Virginia lawmakers to phase out use of the terms "climate change" and "sea level rise."

Resources:
Scientific America blog on the North Carolina sea level rise battle.
Wunderground's Greenland page.
Wunderground's sea level rise page.

The Atlantic is quiet
There are no threat areas to discuss in the Atlantic today. The NOGAPS model is predicting formation of a tropical tropical depression in the Western Caribbean this weekend, and takes the storm northwards into Florida early next week. None of the other models is going along with this idea, but there is some support for a broad area of low pressure developing in the Western Caribbean early next week in some of the other models. The waters offshore of North Carolina may be another region to watch, late this week, along the edge of a cold front moving off the U.S. East Coast.

I'll have a new post Wednesday or Thursday.

Jeff Masters

Climate Change Politics Sea level rise

Updated: 12:18 PM GMT on June 13, 2012

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Damaging rains bust the drought in portions of Florida Panhandle

By: JeffMasters, 2:43 PM GMT on June 11, 2012

Flood waters are receding in the rain-drenched Florida Panhandle and coastal Alabama today, where prodigious rains from a moist, tropical airmass interacting with a stalled front brought flooding that caused at least $20 million in damage to the Pensacola, Florida area. The most remarkable rains fell in West Pensacola, where 21.70" was recorded over the weekend. Pensacola airport received 13.13 inches of rain on Saturday, the city's second-highest 1-day rainfall total in recorded history. The only greater 1-day rainfall occurred on October 5, 1934, when Tropical Storm Nine brought 15.29" of rain to the city. Satellite loops of atmospheric precipitable water show that this weekend's heavy rains were caused by a flow of very moist tropical air that originated over the warm waters of the tropical Eastern Pacific and flowed northwards across Mexico and Central America to the Panhandle of Florida. This moist airmass has been replaced by relatively dry air over the Gulf, which should limit rainfall amounts today to the 1 - 2 inch range. A cold front expected to arrive on Tuesday will serve as the focus to bring additional rains of 1 - 2 inches per day to portions of the region Tuesday and Wednesday. Before this weekend's mighty rainstorm, the Florida Panhandle was experiencing severe to extreme drought, with 12 - 15 inches of rain needed to pull the region out of drought. This weekend's rains have busted the drought the extreme western Panhandle, but surrounding regions of Alabama, Georgia, and Florida still need 10+ inches of rain.


Figure 1. Radar-estimated rainfall for the Florida Panhandle from this weekend's rain storm.


Figure 2. Amount of precipitation needed to bust drought conditions over the U.S., as of June 2, 2012. A Palmer Drought Severity Index (PDI) of -0.5 is considered the boundary of where a drought exists. The 12 - 15 inches of rain that fell across the extreme western Florida Panhandle and coastal Alabama over the weekend were enough to bust the drought in those regions. Image credit: NOAA Climate Prediction Center.

Some rainfall amounts from the storm, from 7 pm CDT Thu June 7, through 3 am CDT Sunday June 10, from the latest NOAA Storm Summary:

...ALABAMA...
TILLMANS CORNER 4.3 WNW 10.77"
GRAND BAY 0.6 NW 10.03"
MOBILE DOWNTOWN ARPT 8.97"

...FLORIDA...
WEST PENSACOLA 10.9 SW 21.70"
PENSACOLA RGNL ARPT 15.08"
MILTON 10.9 SSW 14.42"
PENSACOLA 3.8 N 13.88"
JACKSONVILLE 11.6 ENE 4.31"

...GEORGIA...
AUGUSTA/DANIEL FIELD 4.08"
WARNER ROBINS AFB 1.95"
VALDOSTA RGNL ARPT 1.50"

...LOUISIANA...
PONCHATOULA 11.8 E 5.64"
SLIDELL 4.29"
LACOMBE 1.4 N 3.73"
BATON ROUGE 2.5 E 2.26"
NEW ORLEANS/LAKEFRONT 2.13"

...MISSISSIPPI...
PASCAGOULA 7.50"
GULFPORT-BILOXI 6.52"
PASS CHRISTIAN 3.5 NE 4.69"

The Atlantic is quiet
There are no threat areas to discuss in the Atlantic today. The NOGAPS model is predicting formation of a strong tropical disturbance capable of becoming a tropical depression in the Western Caribbean by Sunday, but none of the other models is going along with this idea. We could get something developing in the waters offshore of North Carolina late this week, along the edge of a cold front expected to move of the U.S. East Coast on Tuesday - Wednesday. The GFS model has suggested something could develop in this region in several of its recent runs.

Jeff Masters

Flood Drought

Updated: 2:48 PM GMT on June 11, 2012

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Torrential rain causes widespread flooding in Florida panhandle

By: angelafritz , 2:25 AM GMT on June 10, 2012

Torrential rainfall led to widespread flooding along the northern Gulf Coast on Saturday, and Pensacola came about 2 inches shy of matching its all-time rainfall record for a calendar day: 15.29 inches. On Saturday, Pensacola airport received 13.13 inches of rain. The previous record was set on October 5, 1934, as Tropical Storm 9 of that year was making landfall. The record for any 24 hour period is 17.1 inches, spanning Octover 4-5 in 1934, according to Wunderground weather historian Christopher C. Burt.

A state of emergency was declared for Florida's Escambia County. According to the AP:

Emergency shelters were opened at a few local schools for people who were urged to evacuate from low-lying areas, the newspaper reported. Thousands were without power. Neighboring Santa Rosa County had about 40 homes flooded.

Streets were flooded throughout Mobile, Ala., which got 5.79 inches of rain. County authorities warned residents to stay off the roads until the waters receded and workers could look for damage and downed utilities.


The rain has since ended for now in the Gulf states, but images and video of the aftermath are still pouring in. The area is expected to receive more rain on Sunday, which could last until the middle of next week, as thunderstorms fire along a stationary front which is draped across the coastal states.


Figure 1. Widespread, heavy rain washes onto the Gulf shores on Saturday, enhanced by a lingering stationary front that's draped across the region. The heaviest rain fell in Pensacola, Florida, which came 2 inches shy of breaking its all-time calendar day rainfall record.


Video: Downtown Pensacola still flooded this evening after the rain had stop. The city's airport received 13.13 inches of rain since midnight.

Angela

Flood Extreme Weather

Updated: 1:34 AM GMT on June 11, 2012

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Spring 2012: most extreme season in U.S. history

By: JeffMasters, 2:08 PM GMT on June 08, 2012

Spring 2012 in the contiguous U.S. demolished the old records for hottest spring and most extreme season of any kind, said NOAA's National Climatic Data Center (NCDC) on Thursday. With the warmest March, third warmest April, and second warmest May, the March - April - May spring season was 5.2°F above average--the largest temperature departure from average of any season on record for the contiguous United States. What's truly remarkable is the margin the old record was broken by--spring 2012 temperatures were a full 1°F above the previous most extreme season, the winter of 1999 - 2000. All-time seasonal temperature records are very difficult to break, and are usually broken by only a tenth of a degree. To see the old record crushed by a full degree is a stunning and unparalleled event in U.S. meteorological history.


Figure 1. Temperature rankings for spring 2012 in the Contiguous U.S. Thirty-one states were record warm for the 3-month period, and an additional eleven states had top-ten warmth. Spring 2012 beat the previous record for hottest spring on record, set in 1910, by an remarkable 2°F. Image credit: NOAA/NCDC.

U.S. heat over the past 12 months: a one in half-a-million event
The U.S. record for hottest 12-month period fell for the second straight month in May. The June 2011 - May 2012 temperatures smashed the previous record by a startling 0.4°F, which is a huge margin to break a record by for a 1-year period. The past twelve months have featured America's 2nd warmest summer, 4th warmest winter, and warmest spring on record. Thirty-two states were record warm for the 12-month period, and an additional ten states were top ten warm. Each of the 12 months from June 2011 through May 2012 ranked among the warmest third of their historical distribution for the first time in the 1895-present record. According to NCDC, the odds of this occurring randomly during any particular month are 1 in 531,441. Thus, we should only see one more 12-month period so warm between now and 46,298 AD--assuming the climate is staying the same as during the past 118 years. The unusual warmth was due, in part, to a La Niña event in the Pacific that altered jet stream patterns, keeping the polar jet stream much farther to the north than usual. However, it is highly unlikely that the extremity of the heat during the past 12 months could have occurred without a warming climate. Some critics have claimed that recent record warm temperatures measured in the U.S. are due to poor siting of a number of measurement stations. Even if true (and the best science we have says that these stations were actually reporting temperatures that were too cool), there is no way that measurement errors can account for the huge margin by which U.S. temperature records have been crushed during the past 12-month, 5-month, and 3-month periods.




Figure 2. Three of the top ten warmest 12-month periods in the contiguous U.S. since 1895 have occurred since April 2011. Image credit: NOAA/NCDC.




Figure 3. The average temperature during January - May 2012 was the warmest on record: 5°F above the 20th century average for the period, and 1.3°F above the previous record set in 2000. January - May temperatures have been rising at about 1.8°F per century since 1895. Image credit: NOAA/NCDC.

Second warmest May, warmest year-to-date period on record
May 2012 was the second warmest May in the contiguous U.S. since record keeping began in 1895. Twenty-six states had a top-ten warmest May, and no states had a top-ten coolest May. The January - May 2012 period was the warmest January - May period since record keeping began in 1895, with temperatures 5°F above the 20th century average for the period. This broke the previous record set in 2000 by an unusually large margin--1.3°F.



Figure 4. NOAA's U.S. Climate Extremes Index (CEI) for spring (March - April - May) shows that 2012 had the most extreme spring on record, with 44% of the contiguous U.S. experiencing top-10% extreme weather.

Most extreme spring and January - May period on record
NOAA's U.S. Climate Extremes Index (CEI), which tracks the percentage area of the contiguous U.S. experiencing top-10% and bottom-10% extremes in temperature, precipitation, and drought, was 44% during the spring March - April - May period. This is more than twice the average value, and spring 2012 was the most extreme season of any kind in U.S. history. A list of the top five most extreme seasons since 1910, as computed using the CEI, show that two of the three most extreme seasons in U.S. history occurred in the past 12 months:

Spring 2012: 44%
Winter 1979: 42%
Summer 2011: 39%
Fall 1985: 39%
Spring 1934: 38%

Remarkably, 81% of the contiguous U.S. had maximum temperatures that were in the warmest 10% historically during spring 2012, and 71% of the U.S. of the U.S. had warm minimum temperatures in the top 10%. The percentage area of the U.S. experiencing top-10% drought conditions during spring was 18%, which was the 19th greatest since 1910. Extremes in 1-day spring heavy precipitation events were the 8th largest on record. The year-to-date January - May period was also the most extreme such period in U.S. history, with a CEI of 43%. Climate change theory predicts that, in general, the climate should warm, wet areas should get wetter, and dry areas should get drier. The spring 2012 Climate Extremes Index reflects this pattern.

Have a great weekend, everyone, and I'll be back Monday with a new post. None of the computer models is predicting tropical cyclone formation in the Atlantic through June 15.

Jeff Masters

Climate Summaries Climate Change Extreme Weather

Updated: 2:51 PM GMT on June 08, 2012

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Hottest rain on record? Rain falls at 109°F in Saudi Arabia

By: JeffMasters, 11:24 AM GMT on June 07, 2012

Pilgrims to the holy city of Mekkah (Mecca), Saudi Arabia must have been astonished on Tuesday afternoon, June 5, when the weather transformed from widespread dust with a temperature of 113°F (45°C) to a thunderstorm with rain. Remarkably, the air temperature during the thunderstorm was a sizzling 109°F (43°C), and the relative humidity a scant 18%. It is exceedingly rare to get rain when the temperature rises above 100°F, since those kind of temperatures usually require a high pressure system with sinking air that discourages rainfall. However, on June 4, a sea breeze formed along the shores of the Red Sea, and pushed inland 45 miles (71 km) to Mekkah by mid-afternoon. Moist air flowing eastwards from the Red Sea hit the boundary of the sea breeze and was forced upwards, creating rain-bearing thunderstorms. According to weather records researcher Maximiliano Herrera, this is the highest known temperature that rain has fallen at, anywhere in the world. He knows of one other case where rain occurred at 109°F (43°C): in Marrakech, Morocco on July 10, 2010. A thunderstorm that began at 5 pm local time brought rain at a remarkably low humidity of 14%, cooling the temperature down to 91°F within an hour.



Figure 1. Thunderstorms at 109°F? This true-color satellite image of Saudi Arabia taken at 2:10 pm local time (11:10 UTC) on June 5, 2012, shows a line of thunderstorms that developed along the edge of the sea breeze from the Red Sea. Three hours after this image was taken, Mekkah (Mecca) recorded a thunderstorm with rain and a temperature of 109°F (43°C.) Image credit: NASA.

More like a hot shower than a cooling rain?
Thunderstorms often produce big drops of cold rain, since these raindrops form several thousand meters high in the atmosphere, where temperatures are much cooler than near the surface. Some drops even get their start as snow or ice particles, which melt on the way to the surface. Additional cooling of the drops occurs due to evaporation on the way down. However, in the case of the June 4, 2012 Mekkah storm, I think the rain was probably more like a hot shower. Large raindrops, like the kind thunderstorms produce, fall at a speed of about 10 meters per second. A balloon sounding of the upper atmosphere taken at 3 pm local time at a nearby station (Al-Midinah) found that the bottom 1000 meters of the atmosphere was 97°F (36°C) or warmer. Thus, the thunderstorms' raindrops would have been subjected to 100 seconds of some very hot air on the way to the surface, likely warming them above 100°F by the time they hit the ground. A classic 1948 study of raindrops found that, in many cases, raindrop temperatures start off cold in the first few minutes of a rain shower, then warm up to within 1°C (1.8°F) of the air temperature within a few minutes. With the air temperature a sizzling 109°F (43°C) at the time of the June 4 thunderstorm in Mekkah, the raindrops could easily have been heated to a temperature of over 105°F (41°C) by the time they reached the surface!

How hot can it be and still rain?
If substantial amounts of liquid water are present on the Earth, the planet will experience rain, as long as some mechanism to lift the warm, moist air and cause condensation can be found. If the climate continues to warm as expected, we should see an increasing number of cases where it rains at temperatures well above 100°F. On Saturday, June 2, the temperature in Mekkah hit 51.4°C (124.5°F), a new record for the city, and just 1.1°F (0.6°C) below the all-time hottest temperature record for Saudi Arabia (125.6°F, or 52°C, recorded at Jeddah on June 22, 2010.) I expect that 20 - 40 years from now, we'll begin seeing occasional cases where rain falls at a temperature above 117°F (47°C) in the desert regions of North Africa and the Middle East.

I'll have a new post by Friday afternoon.

Jeff Masters

Heat

Updated: 3:22 PM GMT on August 15, 2012

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A Letter to Mother Nature: a book review

By: JeffMasters, 11:52 AM GMT on June 05, 2012

One of the features of wunderground.com that I'm most proud of is one all of you can take credit for--our wunderphotos. Each day, users of the web site upload an average of 500 - 600 photos of some of the most beautiful and spectacular natural phenomena on the planet. We all share the same atmosphere, and one really gets a sense of that connection when we look at the wunderphotos, which come from every corner of the planet. Since 2003, 1.5 million wunderphotos have been uploaded, with over half a million just in the past three years. We have a dedicated team of volunteer reviewers that screen each photo, and I owe a big thank-you to all of you who have served as wunderphoto moderators. One of our most dedicated wunderphotographers, Lucy Woodley (wunderhandle: observing), was inspired to collect a set of 90 of her favorite wunderphotos and put them into a book. Her effort, A Letter to Mother Nature, was published this May. Each photo in the book has a sentence above it, poetically describing the scene below. It only takes a few minutes to whip through the book, but the spectacular images and thoughtful text invite one to linger longer and contemplate the natural beauty we are surrounded by. Here's a sampling of the text and images from the book, with wunderphotos by SunsetFL, CameraDiva, and Sharrose:

Dear Mother Nature,
Quite simply, I am in awe
of you and here is why...

You remind us to always look up...



...for there are great wonders overhead.



We can't resist dancing in your meadows.




A Letter to Mother Nature is $14.99 (paperback) from amazon.com. Proceeds from sale of the book go to support the disaster relief charity Portlight.org, founded by members of the wunderground community. I give A Letter to Mother Nature my highest rating, five out of five stars.

Rare transit of Venus today
I hope all you wunderphotographers will help document for us today a rare celestial happening--a transit of Venus across the sun. On June 5th at 3:09 pm PDT, Venus will begin a historic 7-hour transit of the solar disk, appearing as a dark spot against the sun's blazing face. This will be the last transit of Venus across the sun until 2117. As always, when viewing the sun, be sure to do it indirectly, or use a proper filter such as a #14 welder's glass to block the sun's eye-damaging rays. NASA.gov has more info. I'll link the best wunderphotographs taken of today's transit at the bottom of this post tonight and Wednesday morning. Below is one from Venus' last transit of the sun, back in 2004. Thanks, wunderphotographers!

Jeff Masters

Book and Movie Reviews

Updated: 4:21 PM GMT on June 06, 2012

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Rick Knabb takes over as director of NHC

By: JeffMasters, 12:56 PM GMT on June 04, 2012

Today marks the first day of work for the National Hurricane Center's new director--Dr. Rick Knabb, who worked at NHC from 2005 - 2008 as a senior hurricane forecaster before leaving in 2008 to take a position as deputy director and director of operations of the Central Pacific Hurricane Center (CPHC) and NWS Forecast Office in Honolulu, Hawaii. Dr. Knabb left Hawaii to take a position as The Weather Channel's hurricane expert in 2010, where he worked until May of this year. He thus brings a unique mix of NHC experience, managerial experience, and experience communicating to the public on-camera, to the NHC director's job. He will fit in very comfortably with the NHC staff, and should make an excellent NHC director. Knabb, 43, is the second youngest director of NHC. Only Neil Frank, who served as director from 1973 - 1987, was younger at the time he took the job.

Dr. Knabb takes over the directorship of NHC from Bill Read. Read took the post of NHC director in 2008 after Bill Proenza stepped down following a stormy six-month tenure where much of staff revolted against him. In the wake of the turmoil stirred up by Proenza, Read brought stability to the Hurricane Center. Read's management ability, easy-going style, and solid communication skills made Read an excellent choice for director of NHC, and he will be missed. “I will have been in charge just shy of four and a half years on June 1,” Read wrote in a letter to hurricane center staff earlier this year. “I had no idea I would ever be considered for such an honor. It’s been quite a ride and I’m blessed to hit the exit ramp in my career after working with you all.” Read was lucky enough in his four-year tenure at NHC to never oversee a landfalling major hurricane in the U.S.

National Hurricane Center Directors:
Gordon Dunn, 1965 - 1967
Robert Simpson, 1967 - 1973
Neil Frank, 1973 - 1987
Bob Sheets, 1987 - 1995
Robert Burpee, 1995 - 1997
Jerry Jarrell, 1998 - 2000
Max Mayfield, 2000 - 2007
Bill Proenza, January - July, 2007
Ed Rappaport (interim), July 2007 - January 2008
Bill Read, 2008 - 2012
Rick Knabb, 2012 - ????

It looks like Dr. Knabb will have a quiet first week on the job--there are no threat areas to discuss in the Atlantic, and none of the computer models is predicting tropical storm development over the next seven days.

Jeff Masters

Hurricane Politics

Updated: 1:49 PM GMT on June 04, 2012

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The 2012 Atlantic hurricane season begins: what is in store?

By: JeffMasters, 2:56 PM GMT on June 01, 2012

The 2012 Atlantic hurricane season is officially underway. With two early season storms, Alberto and Beryl, having already come and gone, this year's season has gotten off to a near-record early start. Since reliable record keeping began in 1851, only the hurricane seasons of 1908 and 1887 had two named storms form so early in the year. So, will this early pace continue? What will this year's hurricane season bring? Here are my top five questions for the coming season:

1) All of the major seasonal hurricane forecasts are calling for a near-average season, with 10 - 13 named storms. Will these pre-season predictions pan out?

2) How will the steering current pattern evolve? Will the U.S. break its six-year run without a major hurricane landfall, the longest such streak since 1861 - 1868?

3) Will the 420,000 people still homeless in Haiti in the wake of the January 2010 earthquake dodge a major tropical cyclone flooding disaster for the third consecutive hurricane season?

4) How will new National Hurricane Center director Rick Knabb fare in his inaugural season?

5) Will the Republican National Convention, scheduled to occur in Tampa during the last week of August, get interrupted by a tropical storm or hurricane?


Figure 1. True-color MODIS satellite image of Beryl taken at 2:35 pm EDT May 27, 2012 by NASA's Aqua satellite. At the time, Beryl was a tropical storm with winds of 65 mph.

Quick summary of the early-season atmosphere/ocean conditions in the Atlantic
Strong upper-level winds tend to create a shearing force on tropical storms (wind shear), which tears them apart before they can get going. In June, two branches of the jet stream, the polar jet to the north, and a subtropical jet to the south, typically bring high levels of wind shear to the Atlantic. The southern subtropical jet currently lies over the Caribbean, and is expected to remain there the next two weeks, making development unlikely in the Caribbean. Between the subtropical jet to the south and the polar jet to the north, a "hole" in the wind shear pattern formed during May off the Southeast U.S. coast, and this is where both Alberto and Beryl were able to form. Their formation was aided by the fact ocean temperatures off the U.S. East coast are quite warm--about 1 - 2°C above average. A wind shear "hole" is predicted to periodically open up during the next two weeks off the Southeast U.S. coast, making that region the most likely area of formation for any first-half-of-June tropical storms. However, none of the reliable computer models are predicting tropical storm formation in the Atlantic between now and June 8.

May ocean temperatures in the tropical Atlantic are approximately the third coolest we've seen since the current active hurricane period began in 1995. SSTs in the Main Development Region (MDR), between 10 - 20°N latitude, from the coast of Africa to the Central America, were about 0.35°C above average in May, according to NOAA's Coral Reef Watch. Tropical storm activity in the Atlantic is strongly dependent on ocean temperatures in this region, and the relatively cool temperatures imply that we should see a delayed start to development of tropical waves coming off the coast of Africa and moving into the Caribbean, compared to the period 1995 - 2011. An interesting feature of this month's SST departure from average image (Figure 2) is the large area of record-warm ocean temperatures off the mid-Atlantic and New England coasts, from North Carolina to Massachusetts. Ocean temperatures are 3 - 5°C (5 - 9°F) above average in this region. This makes waters of much above-average warmth likely to be present during the peak part of hurricane season, increasing the chances for a strong hurricane to affect the mid-Atlantic and New England coast.

The upper-level jet stream pattern is critical for determining where any tropical storms and hurricanes that form might go. Presently, these "steering currents" are in a typical configuration for June, favoring a northward or northeastward motion for any storms that might form. However, steering current patterns are fickle and difficult to predict more that seven days in advance, and there is no telling how the steering current pattern might evolve this hurricane season. We might see a pattern like evolved during 2004 - 2005, with a westward-extending Bermuda High, forcing storms into Florida and the Gulf Coast. Or, we might see a pattern like occurred during 2010 - 2011, with the large majority of the storms recurving harmlessly out to sea. That's about as helpful as a weather forecast of "Sho' enough looks like rain, lessen' of course it clears up," I realize.


Figure 2. Departure of sea surface temperature from average for May 31, 2012. Image credit: NOAA/NESDIS.

Colorado State predicts a slightly above-average hurricane season
A slightly above-average Atlantic hurricane season is on tap for 2012, according to the seasonal hurricane forecast issued June 1 by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). The CSU team is calling for 13 named storms, 5 hurricanes, and 2 intense hurricanes, and an Accumulated Cyclone Energy (ACE) of 80, which is 87% of average. This is very close to the 1981 - 2010 average of 12 named storms, 6 hurricanes, and 3 major hurricanes. Hurricane seasons during the active hurricane period 1995 - 2011 have averaged 15 named storms, 8 hurricanes, and 4 major hurricanes, with an ACE index 153% of the median. The forecast calls for an average chance of a major hurricane hitting the U.S., both along the East Coast (28% chance, 31% chance is average) and the Gulf Coast (28% chance, 30% chance is average). The risk of a major hurricane in the Caribbean is also average, at 39% (42% is average.) The CSU teams expects we will have a weak El Niño develop by the peak of this year's hurricane season in September, which will cut down on this year's activity by increasing wind shear over the Tropical Atlantic. However, there is considerable uncertainty in this outlook.

Analogue years
The CSU team picked four previous years when atmospheric and oceanic conditions were similar to what we are seeing this year: neutral El Niño conditions in April - May and average tropical Atlantic and far North Atlantic SSTs during
April - May, followed by August - October periods that were generally characterized by weak El Niño conditions and average tropical Atlantic SSTs . Those four years were 2009, a quiet El Niño year with only 3 hurricanes; 2001, which featured two major Caribbean hurricanes, Iris and Michelle; 1968, a very quiet year with no hurricanes stronger than a Category 1; and 1953, a moderately busy year with 14 named storms, 6 hurricanes, and 4 intense hurricanes. The mean activity for these four years was 11.5 named storms, 6 hurricanes, and 2.5 intense hurricanes.

How accurate are the June forecasts?
The June forecasts by the CSU team between 1998 and 2009 had a skill 19% - 30% higher than a "no-skill" climatology forecast for number of named storms, number of hurricanes, and the ACE index (Figure 3). This is a decent amount of skill for a seasonal forecast, and these June forecasts can be useful to businesses such as the insurance industry and oil and gas industry that need to make bets on how active the coming hurricane season will be. Unfortunately, the CSU June 1 forecasts do poorly at forecasting the number of major hurricanes (only 3% skill), and major hurricanes cause 80% - 85% of all hurricane damage (normalized to current population and wealth levels.) This year's June forecast uses a brand new formula tried in 2011 for the first time, so there is no way to evaluate its performance. An Excel spreadsheet of their forecast skill (expressed as a mathematical correlation coefficient) show values from 0.41 to 0.62 for their June forecasts made between 1984 and 2010, which is respectable.


Figure 3. Comparison of the percent improvement over climatology for May and August seasonal hurricane forecasts for the Atlantic from NOAA, CSU and TSR from 1999-2009 (May) and 1998-2009 (August), using the Mean Squared Error. Image credit: Verification of 12 years of NOAA seasonal hurricane forecasts, National Hurricane Center.


Figure 4. Comparison of the percent improvement in mean square error over climatology for seasonal hurricane forecasts for the Atlantic from NOAA, CSU and TSR from 2002-2011, using the Mean Square Skill Score (MSSS). The figure shows the results using two different climatologies: a fixed 50-year (1950 - 1999) climatology, and a 2002 - 2011 climatology. Skill is poor for forecasts issued in December and April, moderate for June forecasts, and good for August forecasts. Image credit: Tropical Storm Risk, Inc.

TSR predicts a near-average hurricane season
The British private forecasting firm Tropical Storm Risk, Inc. (TSR) calls for 12.7 named storms, 5.7 hurricanes, 2.7 intense hurricanes, and an Accumulated Cyclone Energy (ACE) of 98, which is near average. TSR rates their skill level as 23 - 27% higher than a "no-skill" forecast made using climatology, though an independent assessment by the National Hurricane Center (Figure 3) gives them somewhat lower skill numbers, using a different metric than TSR uses. TSR predicts a 48% chance that U.S. landfalling activity will be above average, a 26% chance it will be near average, and a 26% chance it will be below average. TSR’s two predictors for their statistical model are the forecast July-September trade wind speed over the Caribbean and tropical North Atlantic, and the forecast August-September 2012 sea surface temperatures in the tropical North Atlantic.

TSR projects that 3.6 named storms will hit the U.S., with 1.6 of these being hurricanes. The averages from the 1950-2011 climatology are 3.1 named storms and 1.5 hurricanes. They rate their skill at making these June forecasts for U.S. landfalls at 7 - 11% higher than a "no-skill" forecast made using climatology. In the Lesser Antilles Islands of the Caribbean, TSR projects 1.2 named storms, 0.5 of these being hurricanes. Climatology is 1.1 named storms and 0.5 hurricanes.

FSU predicts a slightly above-average hurricane season: 13 named storms
The Florida State University (FSU) Center for Ocean-Atmospheric Prediction Studies (COAPS) issued their fourth annual Atlantic hurricane season forecast, calling for a 70% probability of 10 - 16 named storms and 5 - 9 hurricanes. The mid-point forecast is for 13 named storms, 7 hurricanes, and an accumulated cyclone energy (ACE) of 122. The scientists use a numerical atmospheric model developed at COAPS to understand seasonal predictability of hurricane activity. The model is one of only a handful of numerical models in the world being used to study seasonal hurricane activity and is different from the statistical methods used by other seasonal hurricane forecasters such as Colorado State, TSR, and PSU (NOAA uses a hybrid statistical-dynamical model technique.) The FSU forecast has been the best one over the past three years, for predicting numbers of Atlantic named storms and hurricanes:

2009 prediction: 8 named storms, 4 hurricanes. Actual: 9 named storms, 3 hurricanes
2010 prediction: 17 named storms, 10 hurricanes. Actual: 19 named storms, 12 hurricanes
2011 prediction: 17 named storms, 9 hurricanes. Actual: 19 named storms, 7 hurricanes

Penn State predicts a near-average hurricane season: 11 named storms
A statistical model by Penn State's Michael Mann and alumnus Michael Kozar is calling for an average Atlantic hurricane season with 11.2 named storms, plus or minus 3.3 storms. Their prediction was made using statistics of how past hurricane seasons have behaved in response to sea surface temperatures (SSTs), the El Niño/La Niña oscillation, the North Atlantic Oscillation (NAO), and other factors. The statistic model assumes that in 2012 the current 0.35°C above average temperatures in the MDR will persist throughout hurricane season, the El Niño phase will be neutral to slightly warm, and the North Atlantic Oscillation (NAO) will be near average.

The PSU team has been making Atlantic hurricane season forecasts since 2007, and these predictions have done pretty well:

2007 prediction: 15 named storms, Actual: 15
2009 prediction: 12.5, named storms, Actual: 9
2010 prediction: 23 named storms, Actual: 19
2011 prediction: 16 named storms, Actual: 19

UK Met Office predicts a slightly below-average hurricane season: 10 named storms
The UK Met Office uses a combination of their Glosea4 model and the ECMWF system 4 model to predict seasonal hurricane activity. These dynamical numerical models are predicting a slightly below-average season, with 10 named storms and an ACE index of 90.

NOAA predicts an average hurricane season: 12 named storms
As I discussed in detail in a May 24 blog post, NOAA is calling for 12 named storms, 6 hurricanes, 2 major hurricanes, and an ACE index 102% of normal.



NOAA predicts an average Eastern Pacific hurricane season
NOAA's pre-season prediction for the Eastern Pacific hurricane season, issued on May 24, calls for a near-average season, with 12 -18 named storms, 5 - 9 hurricanes, 2 - 5 major hurricanes, and an ACE index 70% - 130% of the median. The mid-point of these ranges gives us a forecast for 15 named storms, 7 hurricanes, and 3.5 major hurricanes, with an ACE index exactly average. The 1981 - 2010 averages for the Eastern Pacific hurricane season are 15 named storms, 8 hurricanes, and 4 major hurricanes. So far in 2012, there have been two named storms. On average, the 2nd storm of the year doesn't form until June 25. We had a record early appearance of the season's second named storm (Bud on May 21.) Bud was also the strongest Eastern Pacific hurricane on record for so early in the year. Records in the Eastern Pacific extend back to 1949.

Western Pacific typhoon season forecast not available yet
Dr. Johnny Chan of the City University of Hong Kong issues a seasonal forecast of typhoon season in the Western Pacific, but this forecast is not yet available (as of June 1.) An average typhoon season has 27 named storms and 17 typhoons. Typhoon seasons immediately following a La Niña year typically see higher levels of activity in the South China Sea, especially between months of May and July. Also, the jet stream tends to dip farther south than usual to the south of Japan, helping steer more tropical cyclones towards Japan and Korea. With the formation of Tropical Storm Mawar today east of the Philippines, the Western Pacific is exactly on the usual climatological pace for formation of the season's third storm.


Figure 5. Time series of the annual number of tropical storms and typhoons in the Northwest Pacific from 1960 - 2011. Red circles and blue squares indicate El Niño and La Niña years, respectively. Note that La Niña years tend to have lower activity, with 2010 having the lowest activity on record (15 named storms.) In 2011, there were 20 named storms. The thick horizontal line indicates the normal number of named storms (27.) Image credit: City University of Hong Kong.

Hurricane

Updated: 5:54 PM GMT on June 07, 2012

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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