Forecasting the movement of tropical storms/ depressions in the Indian region by a computer oriented technique using , climatology and persistence

A computer-oriented technique for forecasting the movement of tropical storms/depressions in the Indian seas, based on half persistence and half climatology has been tested. The climatological components of the forecast is computed by a computer programmer, by scanning the climatological tracks within a predetermined scan, distance from the centre of the storm to be predicted. The method had been tested on independent data for pre-monsoon and post monsoon storms/depressions during 1961-67, and performance of forecasts categorised. The accuracy-of the forecast by the method compares favourably with other operational objective methods in use elsewhere. Probability ellipses of the errors have been constructed. Results of the forecasts based on experimental real time basis during 1968-70 are also discussed.