Weather Extremes

The Great Bangkok Flood

By: weatherhistorian, 8:30 PM GMT on October 29, 2011

The Great Bangkok Flood

Bangkok, the capital of Thailand, is currently experiencing what is perhaps the greatest flood ever to swamp a city so large in world history. This dynamic Asian megalopolis has a population of around 10 million within the city limits and a metropolitan population of at least 20 million. The flood is affecting virtually every resident and many have evacuated to provinces outside the flood zones.

The worst of the flood was expected to occur on Saturday October 29th as the river that bisects the city, the Chao Praya, was expected to crest at its highest level ever recorded (some 8 feet above normal) and astronomical high tides were expected to peak, possibly causing the drainage of the cities canals and the Chao Praya to back up and push the flood waters into the heart of the city. Fortunately however, it appears that, so far, the dikes have held and the worst-case scenario is not playing out. This could change at a moments notice.

Here are a series of maps outlining the situation:




Above are two satellite views of the south-central Thailand region with Bangkok near the bottom of both images, just north of the Gulf of Siam into which the Chao Praya River flows. The top image shows a typical end of the rainy season flood situation with the flooded portions showing up in black (photo taken on November 13, 2008). The bottom image shows the same view as of October 25th this year.



This map is an overview of the greater Bangkok metropolitan area (about thirty miles by thirty miles square) and what the various flood risks are by district. The downtown Bangkok area is centered on the east side of the Chao Praya River between Nontha Buri and Bang Na. Map produced by Bangkok Post graphics.



Here is a close up of the central Bangkok area and where the flooding situation stands as of Oct. 29th. The color codes are the same as in the top map but the areas in bright yellow are where the flood has most recently expanded into.



This a ‘worst case scenario’ map illustrating the maximum possible depth of flood waters expected in the greater Bangkok area should the dikes fail. One foot is about 25 centimeters.

As of Saturday, much of the Bangkok is shut down and many residents have left the city.

Historical Perspective

It is likely that this flood will surpass the great flood of 1942 both in terms of depth of floodwaters and certainly in terms of economic costs. In recent times, the worst flood to affect the city was in May of 1986 when 15.79” of rain inundated the city in a 12 hour period on May 10-11th of that year. This, however, was a flash flood and although the water reached 3-5 feet deep in much of the downtown area, the waters receded quickly since it was the first rain of the season. Nevertheless, the disruption to city life was such that the mayor lost his job and a new massive sewage infrastructure project was undertaken, the results of which have to some degree alleviated floods in the city since. The system has never been so challenged as now.



A photo of Sanam Luang Park in front of the Grand Palace in Bangkok during the flood of October 1942. Photo source unknown.

Looking into the future, this photo and caption from the Asian Property Report may best sum it up!



Christopher C. Burt
Weather Historian

Flood

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Update on Drought in Texas and Surrounding Region

By: weatherhistorian, 10:06 PM GMT on October 22, 2011

Update on Drought in Texas and Surrounding Region

The first substantial rains of the year inundated portions of central Texas over the past two weeks providing some welcome relief to a few areas. However, the drought remains the worst on record for most of Texas and New Mexico, and a dust storm reminiscent of the 1930s pummeled the Texas Panhandle and areas south of there just last week.



A dust storm bears down on Lubbock, Texas on October 17th. Photo by John Holsenbeck/AP.



Recent rainfall, illustrated in the above set of precipitation anomaly maps, has alleviated the drought situation in portions of Central Texas.

Texas Drought Situation

In spite of the recent rainfall most of Texas remains in a critical drought situation as the latest drought monitor maps for the state indicate:





Two cartographic views of the drought in Texas. The top map is the drought monitor map based largely on soil moisture and at bottom is the Keetch-Byram Drought Index map which is designed to assess fire danger on a scale from 0 (low fire danger) to 800 (extreme fire danger).

Some sites, such as Amarillo and Lubbock, are on track for their driest calendar year on record and have already established their driest water year (Oct. 1-Sept. 30) ever observed. For the state as whole, the January through September period has ranked as the direst since at least 1895.



The latest statewide precipitation ranking map for the past 117 years for the year 2011 as of September 30th. Both Texas and New Mexico have experienced their driest year on record so far. In contrast, Vermont, New York, Ohio, and New Jersey have experienced their wettest year on record so far.

New Mexico Drought Situation

New Mexico, like Texas, has also experienced its driest January through September period on record as the ranking map above indicates. As of Oct. 1, all of the state aside from a couple of small pockets, have experienced well below normal precipitation.



However, since the above map was created some good rainfall has fallen over portions of the state so far this October including Albuquerque, which picked up 1.44” in mid-October, its first substantial rainfall in over a year.

Oklahoma, Kansas, and Louisiana Drought Situation

Drought-stricken portions of western Oklahoma experienced some very heavy rainfall in October alleviating to some degree the short-term drought situation. Western Kansas, however, missed most of the rainfall and Dodge City is on track for possibly its driest calendar year on record. Dodge City has already experienced its driest water year on record when only 7.94” fell between Oct. 1, 2010 and Sept. 30, 2011. Its previous driest water year was 8.36” in 1956. The driest location in the state for the past water year was Sublette 7 WSW where a meager 4.49” was measured. Elkhart picked up only. 6.00”.



Since this graphic was produced on September 30th, Dodge City has picked up an additional 1.20” of precipitation so far this October. Graphic from the NWS office at Dodge City, Kansas.

Western Louisiana also missed the recent rains and remains in exceptional drought. Shreveport has received only about 58% of its normal precipitation so far this year.

Below are some maps and tables summarizing the latest drought and precipitation figures for the region:



The precipitation table above shows the year-to-date (as of Oct. 22) precipitation, what the normal year-to-date precipitation should be, and what the single driest calendar year on record has been for the cities listed. Note the paltry .48" so far this year at Pecos: the driest calendar year in Texas records was 1.64" at Presidio in 1956.





Two overview maps of the seasonal drought outlook for the USA and the amount of additional precipitation needed to return to normal.

Christopher C. Burt
Weather Historian

Drought

Updated: 12:06 AM GMT on October 23, 2011

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September 2011 Global Weather Extremes Summary

By: weatherhistorian, 10:39 PM GMT on October 16, 2011

September 2011 Global Weather Extremes Summary

September was yet another busy month for global weather extremes. Highlights included the worst flooding in Pennsylvania and upstate New York since 1972 as a result of Tropical Storm Lee, devastating wildfires in Texas and Minnesota, the deadliest typhoon to hit Japan since 2004 (Typhoon Talas), and unusual heat in the United Kingdom and Argentina.

Below are the month’s highlights.

NORTH AMERICA

Tropical Storm Lee made landfall in Louisiana on Sept. 4th and brought record-breaking rainfall to portions of Mississippi, Tennessee, Pennsylvania, and New York. All-time 24-hour precipitation records were broken at Jackson, Mississippi with 10.68” on Sept. 4-5, Chattanooga, Tennessee with 9.50” on Sept. 5-6, and Binghamton, New York with an amazing 8.70” on Sept. 7-8. The latter almost doubled the city’s previous record 24-hour rainfall of 4.68” set just last year on Sept. 30-Oct. 1. The storm also helped Binghamton set its all-time wettest month on record with a total of 16.58” (old record 11.45” in June 2006). It was also the wettest September on record (since 1895 at least) for the state of Pennsylvania.

The flooding in Pennsylvania, New York, and New Jersey was the most devastating since Tropical Storm Agnes in June 1972.



Storm-total rainfall map of Pennsylvania for Tropical Storm Lee. The map shows how much precipitation was recorded at various COOP sites during the period of Sept. 5-8. The point maximum was 15.20” at Elizabethtown, Lancaster County.

In contrast, the drought in Texas culminated in a series of wild fires in the south central portion of the state near Austin. Four people were killed and some 1,600 homes destroyed. A forest fire in northern Minnesota consumed 93,000 acres in the Pagami Creek area, the largest fire in Minnesota in over 90 years.



This is actually a color photo, not black and white, of ash coated ground and charred trees in Bastrop State Park, Texas following the wild fire event in September. Photo by Pat Sullivan/AP.

The coldest temperature measured in the northern hemisphere this past month was -41.1°F (-40.6°C) at Summit station, Greenland on Sept. 30th.

SOUTH AMERICA and CENTRAL AMERICA

Unusual warmth affected Argentina, southern Brazil, and Bolivia during September. Argentina reported its warmest average maximum temperature (for September) in 50 years. The hottest reading recorded in the southern hemisphere was 110.5°F (43.6°C) at Villamontes, Bolivia. All-time absolute maximum temperature records were recorded in Ver Gleba Celeste, Brazil with 106.2°F (41.2°C) and Floriana City, Brazil 107.6°F (42.0°C). San Jose de Chiquitos, Bolivia tied its all-time heat record with a reading of 105.8°F (41.0°C).

EUROPE

The United Kingdom recorded its 6th warmest September on record and Spain its driest since 1988. In the U.K. an unusual and unprecedented late September heat wave brought record temperatures to much of the country. The highest reading was 84.6°F (29.2°C) at Cambridge and Sutton Bonington (Nottinghamshire) on the 30th. The heat peaked on Oct. 1st (the details of which will be in my October summary). The remnants of Hurricane Katia lashed Scotland on Sept. 12th resulting in several storm-related fatalities and a peak wind gust of 86mph at Glen Ogle. However, it was a storm on the Isle of Wight on Sept 6th that produced the top wind gust for the month of 87mph at Needles Old Battery. The coldest temperature in the U.K. during September was 31.3°F (-0.4°C) at Tyndrum, Stirling on Sept. 15th. The maximum 24-hour rainfall reported in the U.K. was 3.13” (79.4mm) at Capel Curig, Conwy on Sept. 5-6th.

AFRICA

I am unaware of any notable extreme weather events in Africa this past September.

ASIA

Significant typhoons impacted the Philippines (Typhoon Nesat) and Japan (Typhoons Talas and Roke) during the month. Nesat flooded Manila on Sept. 26-27 and brought wind gusts as high as 106mph. Some 55 people were reported killed as a result of the storm. Typhoon Talas struck Japan on Sept. 2 with fierce winds and flooding rains resulting in the deaths of at least 73. It was the deadliest typhoon to strike the country since 2004. Rainfall rates averaged almost 3”/hr at Yamanakoko, Yamanashi and the storm total of 65.06” (1652.5mm) at Nara was an all-time single-storm total for Japan. It was estimated that even greater amounts of up to 80” (2000mm) fell in mountainous regions of Nara Prefecture. Typhoon (Roke) struck Tokyo on Sept. 21st with winds of up to 130mph. Approximately 13 deaths were reported.



Typhoon Roke at her strongest as a Category 4 strength storm on Sept. 20th as it approached Japan. NASA image.

Heavy monsoon flooding was reported in Cambodia, Thailand, India, Pakistan, and China during the month. In Pakistan some 200,000 were displaced and over 200 killed during floods in the southeastern region of the country during the first week of September. In India, the eastern state of Orissa was swamped by torrential rains that caused flooding resulting in the deaths of at least 32. The flooding in Thailand and Cambodia gradually worsened over the course of the month culminating in catastrophic flooding in October (more on this in my October summary next month). Flooding in the provinces of Sichuan, Henan, and Shaanxi in China during the middle of the month led to scores of deaths. The flooding in Sichuan was reported to be the worst since records began in 1847.

The hottest temperature in the northern hemisphere and the world during September was measured at Abdaly, Kuwait on Sept. 5th with a reading of 118.2°F (47.9°C).

AUSTRALIA

In Australia minimum temperatures averaged the coldest for September since 1985 and in Western Australia since 1978.



Average minimum temperature deciles for September in Australia, the coolest such since 1985. Map courtesy of the Australian Bureau of Meteorology.

The warmest temperature in the country during the month was 103.5°F (39.7°C) at Bradshaw, Northern Territory on Sept. 30th and the coldest 12.2°F (-11.0°C) at Charlotte Pass, new South Wales on Sept. 22nd. The maximum calendar day precipitation measured was 6.89” (175mm) at Wyong, New South Wales on Sept. 26th.

ANTARCTICA

The coldest temperature in the southern hemisphere and the world during September was -112.4°F (-80.2°C) recorded at Dome Fuji on Sept. 18th. This was also the coldest temperature measured in the world for the year 2011 (since Antarctica is now entering its spring and summer and lower temperatures than this are not expected to occur).

KUDOS Thanks to Maximiliano Herrera for global temperature extremes data and Stephen Burt for the U.K. extremes.

Extreme Weather

Updated: 7:14 PM GMT on October 17, 2011

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Tropical Storm Superlatives for Australia and the Indian Ocean

By: weatherhistorian, 8:42 PM GMT on October 06, 2011

Tropical Storm Superlatives for Australia and the Indian Ocean

In this last blog of my series on tropical storm superlatives, I cover the Indian Ocean Basin which includes the Bay of Bengal where the world’s deadliest tropical storms occur, as well Australia’s cyclone superlatives. Both the east and west coasts of Australia are occasionally pounded by intense tropical storms that originate in the South Pacific and Indian Ocean respectively, but for the sake of simplicity I am lumping both sources that affect Australia in this single blog.



This map shows the average number of tropical storms on an annual basis to affect the Australian and the southern Indian Ocean regions. Map courtesy of the Australian Bureau of Meteorology.

Australian Tropical Storm Superlatives

Most Intense Australian Cyclone

Tropical storms are called cyclones in both the Indian Ocean region and Australia. Since Australia does not have the equivalent of America’s hurricane hunter air reconnaissance the minimum barometric pressures of cyclones in the region are normally estimated using Dvorak and satellite observations rather than actual measurements when the storms are still offshore. Consequently there are differences of opinion between various agencies that monitor storms approaching Australia.



The above maps show the paths of all tropical storms to affect Australia during the period of 1906-2006 (top map). Unfortunately, the meaning of the various colors used for the paths is not explained although I assume they have to do with relative intensities of the individual storms that are tracked. Map courtesy of the Australian Bureau of Meteorology.

According to Australia’s Tropical Cyclone Warning Centre (based in Brisbane) Severe Tropical Cyclone Monica reached its greatest intensity on April 23, 2006 after it had crossed Queensland and entered the Gulf of Carpentaria north of Australia when a central barometric pressure of 905mb (26.72”) was reached. However, the U.S. Navy Joint Typhoon Warning Center, which was also monitoring the cyclone, estimated the pressure to have been at least 879mb (25.96”) and some calculations even came up with a figure of 969mb (25.66”), which would be a world record if true. In any case, even at 905 mb, Monica would at least tie with Cyclone Orson in April 1989) as Australia’s most intense tropical storm. Sustained winds of 185mph with gust to 225mph were theorized. Fortunately, Monica passed over sparsely populated areas of Australia and no fatalities and little damage were reported.



An infrared image of Cyclone Monica at her peak intensity on April 23, 2006. Her Dvorak intensity was a perfect 8.0 at this, time the highest on the scale, and winds were estimated to be gusting over 200mph. Image from wunderground.com

Below is a list of the ten most intense cyclones to strike Australia in terms of lowest barometric pressure measured at a land location:



Most Destructive Australian Cyclone

Cyclone Tracy struck the city of Darwin on the coast of Australia’s Northern Territory on Christmas Day 1974 killing 71 and destroying 70% of the city’s structures. The storm was extremely compact with gale winds extending only in a 31 miles radius from its 4 mile-wide eye. In spite of its small size, winds at its center were estimated to be as high as 150mph with a gust of 135mph actually measured at Darwin Airport before the anemometer was blown away. 41,000 of the city’s 47,000 residents were rendered homeless and damage was calculated at $800 million in 1974 US dollars (about $3.5 billion in current dollars).



A photo of the incredible destruction to Darwin following the passage of Cyclone Tracy on Dec. 25, 1974. 70% of the city was destroyed and 71 lives were lost. Photo credit unknown.

The deadliest cyclone in Australian history, and the country’s deadliest natural disaster, was the Great Bathurst Bay Cyclone of 1899. Some 300-400 lives were lost along the far northeastern coast of Queensland mostly the crews of pearling vessels.

Highest Measured Wind Speeds in Australian Cyclones

The highest wind speed ever ‘officially’ recorded on earth occurred when Cyclone Olivia passed over a gas platform off the coast of Barrow Island in Western Australia and produced a measured wind gust of 253mph (408km/h) on Oct. 4, 1996. Although Olivia was not one of Australia’s most potent cyclones it is suspected that a mesovortex in the eye wall of the storm passed directly over the observation site producing the extraordinary value. The anemometer ( a heavy duty three-cup Synchrotac) was subsequently checked for accuracy and passed several tests for such.

Below is a list of the highest measured wind gusts at land locations in Australia during the passage of severe tropical cyclones:



Greatest Rainfall Associated with Cyclones in Australia

The greatest precipitation total as a result of a tropical storm was the 99.09” that fell over a three-day period at Bellenden Ker, Queensland January 4-6, 1979. This same storm also produced Australia’s greatest 24-hour total of 44.92” at Bellenden Ker on Jan. 4, 1979. A cyclone in February 1893 deposited 67.52” in three days at Mooloolah, Queensland.

Greatest Cyclone Storm Surge in Australia

The Great Bathurst Bay Cyclone of March 5, 1899 produced a storm surge of some 42 feet when it crashed ashore in northern Queensland according to eyewitness accounts and debris damage. This is the highest storm surge reliably recorded anywhere on earth.

Indian Ocean Cyclone Superlatives

The cyclones in the Indian Ocean basin primarily occur in the Bay of Bengal region between India and Burma (Myanmar), the Arabian Sea between India and the Arabian Peninsula, and in the Southern Indian Ocean between Australia and Madagascar off Africa’s east coast. The former is most noteworthy for the mass casualties that occur in India, Bangladesh, and Burma, and the latter for the world-record rainfalls that happen on the island of Reunion some 500 miles east of Madagascar.



A map showing the paths of all tropical storms in the Bay of Bengal and Arabian Sea between 1986-2006.

Most Intense Indian Ocean Cyclones

Cyclone data details are sketchy for this entire region so far as tropical storm intensities are concerned but the lowest barometric pressure actually measured in the Bay of Bengal was during a severe cyclone in 1833 when the British vessel S.S. Duke of York reported a measurement of 891mb (26.30”) while passing through the eye of a cyclone.



This map illustrates how cyclones affect India by time of year of occurrence, regions most often affected, and historical storm surges observed at various points along the coastline. Map from Compare Infobase Ltd.

The lowest pressure reached in a Southwest Indian Ocean cyclone I am aware of was 895mb (26.42”) during Cyclone Gafilo on March 6, 2004 just prior to striking Madagascar (see end of blog entry about ‘Deadliest Cyclones to affect Africa’).

Deadliest Indian Ocean Cyclones

All of the deadliest tropical storms on earth have occurred in the Bay of Bengal when tremendous storm surges have swamped the low-lying coastal regions of Bangladesh, India, and Burma. The worst of all was the Great Boha Cyclone of November 12-13, 1970 when a 40-foot storm surge overwhelmed the delta islands of the Brahmaputra and Ganges Rivers in Bangladesh. An estimated 300,000-500,000 perished. This storm is also considered to have produced the greatest storm surge of any Indian Ocean cyclone although similar surges may have occurred during the 1733 and 1876 cyclones.



A storm surge graphic of the Great Boha Cyclone of November 1970. The bars indicate how high the storm surge was at various locations along the coasts of India and Bangladesh in feet. Each bar is ’48 feet’ long and the green shading inside the bars shows how many feet (out of 48’) the surge reached. The greatest height was 40 feet at Hatia, Bangladesh. Graphic from ‘Extreme Weather: A Guide and Record Book’ based upon data supplied by the Indian Meteorological Department.

Below is a list of the ten deadliest cyclones to affect this region (these figures vary from source to source, and the Chittagong Cyclone casualties may have been much lower, hence the list is composed of 11 cyclones rather than ten):



The deadliest cyclone to affect the western coast of India (Arabian Sea region) was that of 1882 when 100,000 were killed in and around Bombay.

Greatest Rainfall Associated with Indian Ocean Cyclones

Many of the world’s greatest point rainfall records can be attributed to cyclones that pass over the Indian Ocean island of Reunion. The reason for this is that the island has a 10,000-foot volcanic peak that produces a tremendous orographic effect on the moisture associated with tropical storms. The French Meteorological Service maintains a network of rain gauges on the slopes of the mountain. Below is a list of the world-record rainfalls that have been recorded here during cyclone events:



Deadliest and Most Destructive Cyclone to Hit Eastern Africa

Cyclone Gafilo (mentioned above) was the most intense tropical cyclone to strike Africa when it hit Madagascar with winds estimated at 150mph on March 6, 2004. The storm caused the deaths of 285 people on the island and when a ferry was sunk offshore with the loss of 113. Probably the deadliest cyclone to hit Africa in modern records was Cyclone Leon-Eline that brought devastating floods to Mozambique and South Africa after striking the coast of Mozambique on Feb. 22, 2000. At least 1,000 deaths were directly attributed to this storm.

Christopher C. Burt
Weather Historian

Hurricane

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About weatherhistorian

Christopher C. Burt is the author of 'Extreme Weather; A Guide and Record Book'. He studied meteorology at the Univ. of Wisconsin-Madison.