New Delhi: Southwest monsoon seasonal (June to September) rainfall over the country as a whole is most likely to be normal this year, the India Meteorological Department (IMD)’s Long Range Forecast showed.
Last year, 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-stage forecasting strategy. The new strategy uses a newly developed Multi-Model Ensemble (MME) forecasting system based on coupled global climate models (CGCMs) from different global climate prediction and research centres including IMD’s Monsoon Mission Climate Forecast System (MMCFS) along with the existing statistical forecasting system to generate these forecasts.
For generating the MME forecast for 2022 southwest Monsoon season rainfall, IMD used the April initial condition. It said it used the best models among the climate models with the highest skill over the Indian monsoon region have been used to generate multi-model forecasts. The MMCFS is one of the four models used for calculating MME forecast.
The MME forecast suggests that the monsoon rainfall during the 2022 monsoon season (June to September) averaged over the country as a whole is likely to be normal (96-104% of LPA). The LPA of the June to September period rainfall over the country as a whole for the period 1971-2020 is 87cm.
The five category probability forecasts for the Seasonal (June to September) rainfall over the country as a whole based on the SEFS forecast are given below, which suggests the highest probability for monsoon seasonal rainfall to be normal (96-104% of LPA).
Quantitatively, the monsoon seasonal (June to September) rainfall is likely to be 99% of the Long Period Average (LPA) with a model error of ± 5%. The LPA of the season rainfall over the country as a whole for the period 1971-2020 is 87 cm.
The IMD said currently, La Niña conditions are prevailing over the equatorial Pacific region. IMD’s latest Monsoon Mission Climate Forecast System (MMCFS) as well as other climate model forecasts indicate that La Niña conditions are likely to continue during the monsoon season.
At present, neutral IOD conditions are present over the Indian Ocean and the latest MMCFS forecast indicates that the neutral IOD conditions are likely to continue until the beginning of the southwest monsoon season. Thereafter, enhanced probability
for negative IOD condition is predicted.
As sea surface temperature (SST) conditions over the Pacific and the Indian Oceans are known to have a strong influence on the Indian monsoon, IMD is carefully monitoring the evolution of sea surface conditions over these Ocean basins.
IMD will issue the updated forecasts for monsoon season rainfall in the last week of May 2022. In addition, to update the April forecast, forecasts for monsoon season (June-September) rainfall for four geographical regions, monsoon core zone and forecast for the month of June also will be issued.
– global bihari bureau
