English: During the past few days (May 15-19, 2003) Tropical Cyclone 01B developed in the Indian Ocean and achieved hurricane status. The storm produced heavy rainfall in Sri Lanka, leading to flash flooding and a large loss of life there. The total rain accumulation, exceeding nine inches, is shown in the false-color image above. The rain accumulation map was produced using the TRMM-based, near-real-time Multi-satellite Precipitation Analysis at NASA’s Goddard Space Flight Center.

In this image, note the huge rainfall footprint produced by Tropical Cyclone 01B as it intensified over the Bay of Bengal. (Here is another, true-color image of the cyclone as it approached the coast of Myanmar in southeast Asia on May 19, 2003.) At first, it would appear that the isolated rainfall pocket located over Sri Lanka bears little relation to the burgeoning tropical storm. However, there is evidence to suggest that the rainstorms that deluged Sri Lanka were associated with an outer “feeder band” of moisture entering the tropical cyclone from the southwest.

The Tropical Rainfall Measuring Mission (TRMM) features a spaceborne weather radar built by the Japanese space agency NASDA. In operation for five years, TRMM has provided unprecedented views of tropical rain events around the globe, and now also provides information on flash flood potential (accessed by visiting the TRMM Web site at http://trmm.gsfc.nasa.gov).