Tropical update; 4th warmest June on record

Thunderstorm activity has increased over the central Gulf of Mexico this morning, thanks to a tropical wave moving westward at 20-25 mph. Winds have increased to 20-25 mph at the Gulf of Mexico buoy 275 miles SSE of Sabine Pass, Texas, but pressures are not falling. Wind shear is 20 knots over the wave, and is expected to remain at least 20 knots over the next two days. This is probably too high to allow tropical development to occur.

Two computer models, the GFS and ECMWF, are indicating the possibility of a tropical storm forming in the mid-Atlantic between Africa and the Lesser Antilles Islands by August 1. This is still a bit early for something to form in this region, given that the SSTs are average there. However, there is a strong tropical wave about to emerge from the coast of Africa that may be something to watch early next week as it moves over the central Atlantic.

Fourth Warmest June on record
June 2007 was the fourth warmest June for the globe on record, and the period January - June of 2007 was the second warmest such period ever, according to statistics released by the National Climatic Data Center. The global temperature record goes back 128 years. The global average temperature for June was +0.55�C (+0.99�F) above the 20th century mean. Over land, June global temperatures were the third warmest ever measured. Ocean temperatures were a bit cooler (eighth warmest on record). All land areas, with the exception of Argentina, were warmer than average during the period January-June 2007.

June temperatures were particularly warm across Southeast Europe, where temperatures soared to 40�C (104�F). At least 40 deaths were blamed on the heat, and electricity demand reached record levels. Winter in the Southern Hemisphere was colder than average in Argentina and Australia, and Johannesburg, South Africa's largest city, received its first significant snowfall since 1981 on June 27.

23rd warmest June on record in the U.S.
In the U.S., June 2007 ranked as the 23rd warmest since record keeping began in 1895. The period January through May was the 18th warmest such period on record. It was the second driest January-June and driest April-June on record in the Southeast. Alabama was hardest hit, with 86 percent of the state's pasture and range lands in poor or very poor condition in early July.


Figure 1. Temperature departure from average for June 2007. Image credit: National Climatic Data Center.

Sea ice extent
Sea ice extent in the Arctic for June was the fourth lowest on record, the second straight month that we haven't had a record low. Arctic sea ice coverage in June has declined by about 10% since measurements began in 1979 (Figure 2).


Figure 2. Arctic sea ice extent for June, for the years 1979-2007. June 2007 had the fourth lowest Arctic sea ice extent since satellite measurements began in 1979. May sea ice coverage has declined about 10% since 1979. Image credit: National Snow and Ice Data Center.

I'll have a new blog Friday.
Jeff Masters