Thermal thickness patterns and tropical storms

Abstract

In this paper, an attempt is made to illustrate the utility of the thermal thickness patterns .on constant pressure chart for forecasting the life cycles of a few tropical storms in the Bay of Bengal   The thickness patterns and the contour  thickness relationship seen on the 500-mb isobaric surface gave useful advance indications about the future movement and intensification or decay of the storms under study, atleast 12 hours earlier than those evident from the synoptic charts. Relative divergence in accordance with Sutcliffe's development term was computcd from the isopleths of h_5oo+h_{l 000} and the total thickness at the 500-mb surface and it was found that the patterns   obtained were qualitatively in good agreement with the subsequent movement and development of the storms. It is also shown that the storms under study were steered mainly by the thermal winds at 500-mb surface over the warm sector rather than by the actual winds at 6  kilometres.