Medium Range Prediction of Summer Monsoon Activities over India vis-a-vis Their Correspondence with the Observational Features

A detailed examination on various aspects of the southwest monsoon over the Indian subcon-tinent using analyses and forecasts of the NCMRWF global data assimilation and forecast system for the years 1994 and 1996 is carried out in this study. Objective procedures developed by Ramesh et al. (1996) based on the monsoon 1995 data are employed in the present work. It is found that all the deterministic features of the summer monsoon viz., the onset, its advancement, stagnation / re-vival and the withdrawal, can reasonably by prognosticated after employing the objective methodologies and monitoring daily variations of certain derived quantities from the large scale analyses and forecasts. Further, a good correspondence of the observed large scale / synoptic scale circulation features and the observed rainfall etc. with the deterministic characteristics of the sum-mer monsoon show a good prospect for real time prognosis of the important summer monsoon ac-tivities over the Indian subcontinent.