A preliminary study of an objective method of forecasting heavy rainfall over Bombay and neighbourhood during the month of July

Abstract

An objective method to forecast the occurrence of heavy precipitation over Bombay and neighbourhood has been presented in this paper. The various synoptic situations generally favourable for heavy rainfall Over the chosen area have been listed and attempts are made to select suitable predictors to cover most of these situations. The predictors should be such that they are capable of lending themselves to objective treatment. A search is also made for the predictor which would provide the maximum possible information concerning the predict and The result has been the evolution of a Heavy Rainfall Prediction Diagram whose co-ordinates are the latitude of kinematic trough line between the longitudes 70° to 75"E at 7000/10,000 ft and the shear at 10,000 ft between Bombay and Ahmedabad. The isohyets on the diagram have been constructed based on past data for the month of July. If on a certain day the co-ordinates of the predictors intersect within the 7 -cm isohyet heavy rainfall should be predicted for Bombay within the next 24 hours.