Globe's 7th warmest July; remarkable heat in Asia; little change to 93L

July 2011 was the globe's 7th warmest July on record, according to the National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center (NCDC). NASA's Goddard Institute for Space Studies rated July the 3rd warmest on record. July 2011 global land temperatures were the 5th warmest on record, and ocean temperatures were the 11th warmest on record. Global satellite-measured temperatures for the lowest 8 km of the atmosphere were the 6th or 3rd warmest in the 34-year record, according to Remote Sensing Systems and the University of Alabama Huntsville (UAH). Arctic sea ice in July was the lowest on record, going back to 1979.


Figure 1. Departure of temperature from average for July 2011. Image credit: National Climatic Data Center (NCDC).

Remarkable heat in Asia
For the second consecutive summer, some of the hottest temperatures in Earth's recorded history have scorched Asia. The six hottest (undisputed) temperatures ever measured in Asia have all occurred in during the past two summers:

1) 53.5°C (128.3°F) at Moenjodaro, Pakistan on May 26, 2010
2) 53.3°C (127.9°F) at Mitrabah, Kuwait on August 3, 2011
3) 53.1°C (127.6°F) at Sulaibiya, Kuwait on June 15, 2010
4) 53.0°C (127.4°F) at Tallil, Iraq on August 3, 2011
4) 53.0°C (127.4°F) at Dehloran, Iran on July 28, 2011
4) 53.0°C (127.4°F) at Sibi, Pakistan, on May 26, 2010


Asia's official all-time hottest temperature is 54°C measured at Tirat Zvi, Israel on June 21, 1942. However, as explained by our weather historian, Christopher C. Burt, this record is under serious dispute. Weather records researchers Howard Rainford and Maximiliano Herrera discovered that the thermograph trace of the record had been mis-read as one degree higher than it actually was, and there were other irregularities with the data. Also, a temperature in excess of 54°C was measured in Mitribah, Kuwait in July 2010, but the temperature sensor was found to be faulty.

Last year, twenty nations set all-time heat records. So far this year, there have been six such records set:

Kuwait recorded its hottest temperature on record on August 3, 2011, when the mercury hit 53.3°C (127.0°F) at Mitrabah. The previous record was 53.1°C in Sulaibiya on June 15, 2010. According to weather records researcher Maximiliano Herrera, who has been corresponding with representatives from the Kuwait Meteorological Center, the reading has been confirmed as authentic. The 53.3°C (127.0°F) at Mitrabah thus represents:

1) New official national record for Kuwait
2) Second highest (undisputed) temperature ever recorded in Asia
3) Highest temperature ever recorded in an Arabic country
4) Third hottest location in the planet together with Lake Havasu City, AZ (after Death Valley, CA and Moenjodaro, Pakistan)
5) A new world record for August

Iraq recorded its hottest temperature on record on August 3, 2011 in Tallil (Ali military airbase), when the mercury hit 53°C (127.4°F). The previous record was 52.3°C recorded at Diwanya FOB airbase a few days before.

Armenia recorded its hottest temperature on record on July 31 in Meghri, when the mercury hit 43.7°C (110.7°F). The previous record was 43.1°C in Meghri on July 17, 2005.

Iran recorded its hottest temperature in its history on July 28, 2011, when the mercury hit 53°C (127.4°F) at Dehloran. The previous previous record was set just one day earlier at Omidieh and Shoshtar, when the mercury hit 52.6°C (126.6°F).

Republic of the Congo set a new all-time extreme heat record on March 8, 2011, when the temperature hit 39.2°C (102.6°F) at M'Pouya. Congo's previous all-time hottest temperature was 39.0°C (102.2°F) at Impfondo on May 14, 2005.

Special mention:
Russia had its hottest temperature on record at a regular synoptic reporting station on July 30, 2011, when the mercury hit 44.3°C (111.7°F) at Divnoe in Russia's Kalmykia Republic. Three hotter temperatures have been recorded at automated stations: 45.4°C in 2010 at a hydrological station at Utta, plus readings of 45°C at El'ton and 44.5°C at Verhjnky Baskunkak in August 1940.

No nations have set an all-time coldest temperature record this year, or did so in 2010.

Weather records researcher Maximiliano Herrera is the primary source of the weather records listed here; he maintains a comprehensive list of extreme temperature records for every nation in the world on his website.

Gert misses Bermuda
Tropical Storm Gert brushed by Bermuda yesterday, bringing one brief rain shower and top winds of just 21 mph to the Bermuda Airport. Gert is headed northeastwards out to sea over colder waters, and does not have long to live. Gert is the 7th consecutive named storm in the Atlantic that has not reached hurricane strength. This is the first time that has occurred since record keeping began in 1851. However, it is quite possible such an event occurred before we had satellites to identify weak tropical storms that stayed out to sea. The previous record was six consecutive tropical storms without a hurricane, set most recently in 2002. While ocean temperatures in the tropical Atlantic have been very warm, ranking as the 3rd warmest on record during July, the atmosphere has been more stable and drier than usual, making it difficult for this year's storms to attain hurricane strength.


Figure 2. True color MODIS image taken from NASA's Aqua satellite of Tropical Storm Gert at 17:40 UTC on Monday, August 14, 2011. At the time, Gert was near peak strength, as a 60 mph tropical storm. Image credit: NASA.

Caribbean disturbance 93L
A large but disorganized tropical wave, (Invest 93L), is moving westwards at 15 - 20 mph over the eastern Caribbean Sea, a few hundred miles south of Puerto Rico. This wave has a modest amount of heavy thunderstorms and no signs of a surface circulation, though there is some large scale rotation apparent on satellite imagery. Dry air surrounds 93L, and is interfering with development. However, the disturbance is steadily moistening its environment and is under low wind shear of 5 - 10 knots, so it could begin to organize at any time. There is a hurricane hunter mission scheduled for this afternoon into 93L, but this mission will probably be cancelled given 93L's current lack of development.

93L will bring heavy rain showers to southern Haiti on Wednesday, and to Jamaica on Wednesday night. By Thursday, 93L's forward motion will slow to 10 - 15 mph, bringing heavy rains to Northern Honduras on Thursday and Friday, and Belize and Mexico's Yucatan Peninsula by Saturday. Some development of 93L is is likely beginning on Wednesday and Thursday in the Western Caribbean, as the latest SHIPS model forecast shows wind shear remaining in the low range and the atmosphere steadily moistening as 93L enters the Western Caribbean. However, a path too far south near the coast of Honduras may interfere with development, as predicted by the NOGAPS and GFS models, which dissipate 93L over northern Honduras. The best chances for development will probably occur early next week if 93L crosses the Yucatan Peninsula and enters the Gulf of Mexico, assuming the system survives the crossing intact and is not too far south, as predicted by the ECMWF and UKMET models. These models are currently predicting that the steering pattern early next week over the Gulf of Mexico will be similar to what we saw with Tropical Storm Arlene earlier this year, favoring a track towards Northeast Mexico. The HWRF model is predicting a more northerly track for 93L across Jamaica and the western tip of Cuba into the Gulf of Mexico, but this model develops 93L too quickly, unrealistically making it a hurricane by Thursday. The HWRF model thus predicts a deeper storm that would be steered farther to the north due to upper level winds with less of a straight east-to-west motion than a much weaker (and more realistic) 93L would go. Although it is risky to predict what might happen more than five days in advance, the odds of 93L making a U.S. landfall currently appear low, 20% or less. NHC gave 93L a 20% chance of development by Thursday morning in their 8am EDT Tropical Weather Outlook. These odds should probably be bumped up to 30% later today.


Figure 3. Morning satellite image of Invest 93L, taken at 7:45am EDT August 16, 2011. Image credit: NASA/GSFC.

Elsewhere in the tropics
A tropical wave a few hundred miles southwest of the Cape Verde Islands off the coast of Africa is moving westward near 15 - 20 mph, and is expected to arrive in the Lesser Antilles Islands by Saturday. Both the GFS and UKMET models develop this wave into a tropical depression by Friday or Saturday.

Jeff Masters