The barotropic model with the non-divergent stream function derived from wind analysis as input is used for predicting 500mb level flow patterns in the Indian region. Appropriate boundary conditions for computation of the stream function from the observed wind information are pre-scribed. Such boundary conditions are considered suitable for the purpose which maximise kinetic energy in the reconstructed wind and minimise root-mean-square-vector-error between the recon-structed wind and the observed wind.
Using data of a monsoon situation in June 1966, in which a special interest is movement of a monsoon depression from the Head of the Bay of Bengal in a northerly direction, integration is performed in one-hour time step upto a period of 48-hrs. The 24-hrs. forecasts of the flow patterns appear to compare favourably with the observed flow patterns while the 48-hrs. forecasts appear to show considerable departure from the observed patterns. The r. m, s. v. e. between the forecast and observed values of the non-divergent component of the winds for the Indian region are found to be 3.5m/s for 24-hrs. forecasts, and 6.0m/s for 48/hrs. forecasts. The mean vector error between the predicted and the observed positions of the center of the deep depression is 140km for 24-hrs. forecasts, and 205km for 48-hrs. forecasts.