This year, the IMD is likely to revise the monsoon onset dates for a few regions. (Express file photo by Pradip Das)
The India Meteorological Department (IMD) will release the first stage of Long Range Forecast (LRF) for the upcoming Southwest monsoon season on Wednesday.
LRF is the operational monsoon season forecast issued by the Met office for the period of June to September for the whole of India. The forecast, however, does not include regional-level rainfall or specify quantum rainfall for the forecast period. LRF indicates probable rainfall over the country in terms of Long Period Average (LPA), with the countrywide LPA standing set at 89 cm for the season, as per rainfall data for 1951 to 2000.
Every year, the IMD issues LRF in two stages. The first stage forecast is issued in April, followed by the second stage in June. These forecasts are issued using Statistical Ensemble Forecasting System (SEFS) and dynamical coupled Ocean-Atmospheric models. The forecast factors in the ocean conditions and indicated the present position of El Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD).
This year, the IMD is likely to revise monsoon onset dates for a few regions.
However, monsoon onset dates over Kerala are unlikely to see a change. Normally, the Southwest monsoon reaches the Andaman Sea on May 20 and hits Kerala on June 1. Later, the monsoon progresses northwards during rest of June and July.