The seasonal variation in sea surface temperature (SST) in the Indian Ocean is considered an important factor for the onset and subsequent evolution of the Indian summer monsoon (Webster et al. 1998). Prior to the onset of the summer monsoon a substantial area of the Indian Ocean has an SST greater than 28◦C, known as the Indian OceanWarm Pool (IOWP) (Joseph 1990, Vinayachandran and Shetye 1991). A major part of the IOWP has an outgoing long wave radiation below 240Wm−2 (Lukas 1988) and it is a region of deep convection. The IOWP covers the entire north Indian Ocean (equatorial region east of 50◦ E, the Bay of Bengal and the eastern part of the Arabian Sea) during May, with peak SSTs above 30◦C (Vinayachandran and Shetye 1991). In the southeastern Arabian Sea (SEAS), a core of the warm pool (SST > 30◦C) lies in the region of the Lakshadweep Sea during May. This anomalous warm water region in the SEAS is known as the Arabian Sea Warm Pool (ASWP) (Rao and Sivakumar 1999, Anonymous 2001).