IMD predicts above normal southwest monsoon from June to Sept

New Delhi: The India Meteorological Department (IMD) forecast has predicted rainfall over the country as a whole is most likely to be above normal - 104-110 percent of long period average (LPA) - for the 2016 southwest monsoon season from June to September.

"The forecasts for the monthly rainfall for July and August over the country as a whole and for the season rainfall for the four broad geographical regions of India (NW India, NE India, Central India and South Peninsula) have been issued using a six-parameter Ensemble Forecasting System," said IMD Director General Dr. Laxman Singh Rathore, while addressing a press conference here.

The six predictors are - North-East Pacific to North-West Atlantic SST Anomaly Gradient (December+January), South-east Equatorial Indian Ocean Sea Surface Temperature (February), East Asia Mean Sea Level Pressure (February+March), Central Pacific (Nino 3.4) Sea Surface Temperature (March to May+tendency between March to May and December to February), North Atlantic Mean Sea Level Pressure (May) and North-Central Pacific 850 zonal wind gradient (May), he said.

Recent changes in the atmospheric conditions over the Pacific reflect the weakening El Niño conditions. Latest forecast from IMD-IITM (Indian Institute of Tropical Meteorology) coupled model indicate ENSO (El Niño - Southern Oscillations) neutral conditions are likely to continue and turn to weak La Nina conditions in the latter part of the monsoon season. The rapidly declining El Nino conditions became moderate in early April 2016, weak in early May and now have turned to neutral ENSO conditions.

Over Indian Ocean, the sea surface temperatures are warmer than normal over most parts except along the coast off central and South Africa. The latest forecast from IMD-IITM coupled model indicates positive Indian Ocean Dipole (IOD) conditions are most likely during early part of the monsoon season and same to turn to negative IOD during the latter part of the monsoon season.

The Monsoon Mission Experimental forecast, based on the ESSO-IMD-IITM coupled dynamical model, suggests that the monsoon rainfall during the 2016 monsoon season (June to September) averaged over the country as a whole is likely to be 112percent ± 5percent of long period model average (LPMA). The experimental five category probability forecasts for the 2016 monsoon season rainfall over the country as a whole using the experimental dynamical prediction system are 0percent (deficient), 0percent (below normal), 18percent (normal), 18percent (above normal) and 64percent (excess).

Under the Second Stage Forecasts for 2016 Southwest Monsoon Rainfall, quantitatively, the season rainfall for the country as a whole is likely to be 106percent of the long period average (LPA) with a model error of ±4percent. The LPA rainfall over the country as a whole for the period 1951-2000 is 89 cm. Thus there is no change in the updated quantitative forecast from the first stage operational forecast issued on 12th April, 2016.

The season rainfall over Broad Geographical Regions is likely to be 108percent of LPA over North-West India, 113percent of LPA over Central India, 113percent of LPA over South Peninsula, and 94percent of LPA over North-East India all with a model error of ± 8 percent.

The rainfall over the country as a whole is likely to be 107percent of its LPA during July and 104percent of LPA during August both with a model error of ± 9 percent.