Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 15:43 GMT le 20 juillet 2011
The main rainy season rains have failed again in the Horn of Africa--the region of East Africa comprising Somalia, Kenya, and Ethiopia. Rainfall over most of the Horn of Africa between February and July 2011 was 2 - 8 inches (50 - 200 mm) below average, leading to today's official declaration that famine conditions now exist. The region is experiencing a humanitarian emergency with more than 2 million malnourished children needing lifesaving action. The Horn of Africa has two rainy seasons, a main rainy season in April/May, and then the "short rains" of October/November. The main 2010 April/May rainy season brought above average rains to the region. However, the October/November 2010 "short rains" failed, as did the April/May 2011 main rainy season rains. The failure of two consecutive rainy seasons is a devastating blow for East Africa. African countries are highly dependent on rain-fed agriculture for both employment and economic production, with agriculture accounting for more than 50% of gross domestic product and up to 90% of employment across much of the continent (World Development Indicators 2009, World Bank). One third of the population of Africa lives in drought-prone areas (World Water Forum, 2000), and about 25% of the population of Africa currently experiences high water stress. Remarkably, several nations in East Africa have been selling their land to other countries to raise food for export in recent years. These nations include Ethiopia and Sudan, who both receive massive food aid from the U.N. World Food Program. According to the fascinating and sobering book, World on the Edge by Lester Brown, in January 2009, Saudi Arabia celebrated the arrival of the first shipment of rice on land they had acquired in Ethiopia, where the World Food Program was feeding 5 million people at the time. Saudi Arabia has been actively buying land in other countries to raise crops since the recent failure of agriculture in their country after they pumped their aquifers dry. India, South Korea, and Saudi Arabia have all brought land to grow crops in Sudan, which was the site of the World Food Program's largest famine relief effort in 2010. The world is running short of food, and nations that cannot feed themselves are aggressively competing to buy land to grow food where land costs are low, like East Africa.
Figure 1. Rainfall over most of the Horn of Africa between February and July 2011 was 2 - 8 inches (50 - 200 mm) below average, leading to a deadly drought in the region. Image credit: NOAA Climate Prediction Center.
Another day of dangerous heat in the Midwest
The dangerous Central U.S. heat wave of July 2011 will continue to bring another day of exceptionally humid heat to the Midwest today, and will also begin bringing temperatures in the mid-90s with high humidity to much of the mid-Atlantic and New England. The heat index--how hot the air feels when factoring in both the temperature and the humidity--exceeded 100°F in sixteen states in the center of the country on Tuesday, with the dangerous heat extending from Texas northwards to North Dakota, Minnesota, and Wisconsin. At least thirteen deaths are being blamed on the heat in the Midwest. The heat index hit a torrid 129°F at Newton, Iowa on Tuesday, and a heat index in excess of 120° was recorded at several locations in North Dakota, Iowa, Illinois, and Minnesota.
Figure 2. Predicted maximum heat index for Friday, July 22, 2011. Portions of 35 states are predicted to have a heat index in excess of 100°, with a heat index in excess of 115° expected over large portions of Virginia, Maryland, and Delaware. Image credit: NOAA.
Heat wave headed to the Eastern U.S.
The extreme heat will shift slowly eastwards this week, peaking in Chicago today, Detroit and Pittsburgh on Thursday, and New York City and the mid-Atlantic states on Friday. The forecast high of 103° in Washington D.C. for Friday is just 3° below the hottest temperature ever recorded in the city, 106°. This will no doubt stimulate some predictable quotes on global warming. The heat will remain in place over the mid-Atlantic states through Sunday, then ease on Monday when a cold front is expected to pass through. Wunderground's climate change blogger Dr. Ricky Rood has some good insights on the current heat wave in his latest post.
Tropical Storm Bret no threat
Tropical Storm Bret continues to spin off the U.S. East Coast, but is a weak storm with 50 mph winds, and is not expected to affect any land areas. Wind shear is a high 20 - 25 knots, and is expected to remain in the high range for the next three days. The combination of high wind shear and dry air nearby should act to keep Bret from strengthening, and the storm should slowly decay as it heads out to sea over the next few days.
Invest 99L no threat
Satellite imagery suggests that a low pressure system near 34N, 55W, about 500 miles east of Bermuda, is close to tropical depression strength. This system, dubbed Invest 99L, has been given a 60% chance of developing into a tropical depression by NHC. The storm is headed east-northeastwards out to sea, and is not a threat to any land areas. The storm will move over cool ocean waters below 25°C by Thursday morning, so it has just a short window of time to develop.
An African wave worth watching
An African wave near 45W, midway between the coast of Africa and the Lesser Antilles Islands, is currently generating a limited amount of heavy thunderstorms due to the presence of a large amount of dust and dry air from the Sahara. However, this wave has a modest degree of spin to it, and it is possible it could develop once it finds a moister environment near the Bahama Islands early next week. The last few runs of the UKMET model have shown development of this wave by Tuesday over the Bahamas. The ECMWF and NOGAPS models show that this wave will become a strong tropical disturbance by Tuesday over the Bahamas, while the GFS model shows no development. If this wave does develop, it may recurve before hitting the U.S., since the models agree that there will be a large trough of low pressure present over the U.S. East Coast early next week.
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