Seasonal Forecast Of Southwest Monsoon Rainfall - District Level

An empirical model has been proposed for district level seasonal forecast of rainfall during southwest monsoon season. Results relating to meteorological subdivision of Tamilnadu and Pondicherry are discussed. Cloud and rainfall data for a period of 36 years (1972-2008 except 1978) have been used in the study. It has been shown that different features of cloudiness over near equatorial regions of Indian Ocean during pre-monsoon months of April and May contain signals indicating likely performance of subsequent southwest monsoon. These features have been quantified by assigning an index called South Indian Convergence Zone (SICZ) Activity Index (SAI). SAI varies from 1 to 20. Verification of the forecasts has shown that the proposed model is capable of producing 'Useful' forecasts of seasonal rainfall for meteorological sub-division of Tamilnadu and Pondicherry and its districts.