But over the northeastern region alone, the probability of below normal rainfall is more.
The country is divided into four homogenous rainfall regions — Northwest India, South Peninsula, Central India and Northeast and the Monsoon Core Zone — which depicts most of the rainfed agriculture regions.
According to the IMD update, while the SW monsoon is likely to be normal over Northwest India (between 92-108% of LPA) and South Peninsula (between 93-107% of LPA), Central India is likely to receive over normal rainfall (more than 106% of LPA).
But Northeast India is likely to get below normal rainfall (less than 95% of LPA). The monsoon core zone is likely to receive above normal (more than 106% of LPA) rainfall.
The IMD considers normal rainfall to be 96-108% of the long period average (LPA) of the season rainfall over the country for the period 1961-2010, which is 88 cm.
Based on IMD’s Multi Model Ensemble (MME) system for forecasting, the forecast probability of below normal rainfall over NE is more (40%), while the forecast probability for normal rainfall is 33% and the probability of above normal rainfall is just 27%.
It stated, “The updated MME forecast for 2021 southwest monsoon season rainfall has been computed using various coupled global model forecasts with May initial conditions. Climate models with the highest forecast skills over the Indian monsoon region including MMCFS (Monsoon Mission Coupled Forecasting System) have been used to prepare the MME forecast.”
This year, the IMD has implemented a new strategy for issuing monthly and seasonal operational forecasts for the southwest monsoon rainfall over the country by modifying the existing two state forecasting strategy.
The new strategy uses the existing statistical forecasting system to generate these forecasts along with a newly developed Multi-Model Ensemble (MME) forecasting system based on coupled global climate models (CGCMs) from different global climate prediction and research centers including IMD’s Monsoon Mission CFS (MMCFS) model.
The monthly probabilistic forecast for each of the monsoon months will also be issued at the end of the previous month based on MME approach.