India Meteorological Department (IMD) releasese seasonal forecasts of rainfall for the southwest & North East monsoon season
IMD has forecast that quantitatively, the monsoon seasonal rainfall is likely to be 96% of the Long Period Average (LPA) with an error of ± 5%. Forecast assessment suggests 38% of probability for near normal monsoon rainfall.
IMD issues various monthly and seasonal forecasts of rainfall for the southwest monsoon season (June to September). Operational forecasts for the southwest monsoon season rainfall are issued in two stages.
These forecasts are prepared using state-of-the-art Statistical Ensemble Forecasting system (SEFS) that is critically reviewed and improved regularly through in-house research activities.
Since 2012, IMD has been using the dynamical global climate forecasting system (CFS) model, which was developed under the Monsoon Mission. The original coupled ocean-atmospheric model framework of CFS was adopted from the National Centres for Environmental Prediction (NCEP), USA
The CFS model was further modified to provide improved rainfall forecasts over the Indian monsoon region through research efforts taken up under the Monsoon Mission.
The forecast for 2017 southwest monsoon rainfall over the country as a whole based on both the SEFS and the Monsoon Mission Climate Forecasting System (MMCFS) are as follows.
IMD’s forecast uses the following 5 predictors to assess the monsoon pattern in India
The Sea Surface Temperature (SST) Gradient between North Atlantic and North Pacific – December + January
Equatorial South Indian Ocean SST – February
East Asia Mean Sea Level Pressure – February + March
Northwest Europe Land Surface Air Temperature – January
Equatorial Pacific Warm Water Volume – February + March