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 , 1:14 PM GMT on January 19, 2011
At least 43 are dead and thousands still in refugee camps due to extreme flooding in eastern Sri Lanka caused by record monsoon rains. According to the United Nations, the rains in recent weeks in Sri Lanka have been the heaviest in nearly 100 years of record keeping, and the flood that resulted was a 1-in-100 year event, according to The U.N. Global Disaster Alert and Coordination System. Rainfall at Batticaloa, Sri Lanka, during the 42-day period December 1 - January 12 was 1606 mm (63"), which is about how much rain the station usually receives in an entire year (1651 mm, or 65".) Sri Lanka's previous most devastating flooding disaster was the 2004 tsunami, but as The Economist commented, "in terms of the numbers of people displaced and farmland inundated, the floods have been even more devastating than the tsunami of December 2004." Damage estimates start at $500 million, and much of Sri Lanka's agriculture has been severely damaged by the disaster. Also of concern is the large number of land mines from the recent Sri Lanka civil war that may have been unearthed by the floods. Water is also a major concern in the flood-hit area, as fighting between government forces and Tamil Tigers rebels from mid-2007 to May 2009 damaged or destroyed almost all of the water facilities.
Figure 1. A family affected by the 2011 Sri Lanka floods braves the flood waters. Image credit: United Nations.
Sri Lanka is now the fifth nation in the past six month to suffer a flooding disaster unprecedented in its history. As I reported in a previous post, the other four mega-impact floods--the July 2010 Pakistan floods, the December - January Queensland Australia floods, the November 2010 Colombia floods, and the January 2011 Rio de Janeiro floods--were all accompanied by an atmosphere laden with moisture, due, in part, due to sea surface temperatures over nearby ocean areas that were the 2nd or 3rd warmest on record. However, that was not the case for the Sri Lanka floods. Ocean temperatures during December 2010 were 0.2°C below average in the 5x5 degree square of ocean adjoining the island (5N - 10N, 80E - 85E). The floods appear to be due to the normal monsoon rains that typically affect the region this time of year, enhanced by the strong La Niña event occurring in the Eastern Pacific.
Figure 2. Satellite-estimated precipitation over Sri Lanka for January 3 - 9. Up to 18 inches (525 mm) fell over eastern Sri Lanka. Image credit: NASA Earth Observatory.
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