Shillong, April 15: India Meteorological Department (IMD) has predicted southwest monsoon season rainfall (June to September) to be above normal.
In a statement issued on April 15, the department said quantitatively, the seasonal rainfall over the country is likely to be 105% of Long Period Average(LPA) . The LPA of the seasonal rainfall over the country for the period from 1971-2020 was 87 cm.
The IMD will issue the updated forecasts for monsoon season rainfall in the last week of May.
Since 2003, the IMD has been issuing the operational long-range forecast (LRF) for the southwest monsoon seasonal (June-September) rainfall averaged over the country as a whole in two stages. The first stage forecast is issued in April and the second stage or updated forecast was issued by the end of May. In 2021, 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 both dynamical and statistical forecasting system. Multi-Model Ensemble (MME) forecasting system based on coupled global climate models (CGCMs) from different global climate prediction centres, including IMD’s Monsoon Mission Climate Forecast System (MMCFS) are used.
As per the new LRF strategy, the first stage forecast issued in middle of April consists of the quantitative and probabilistic forecasts for the country as a whole, and the spatial distribution of probabilistic forecasts for the tercile categories (above normal, normal, and below normal) of the seasonal (June-September) rainfall over the country.
The second stage forecast issued around end of May consist of update for the seasonal rainfall forecast issued in April along with the probabilistic forecasts for the seasonal rainfall over the four homogenous regions of India (northwest India, central India, south Peninsula and northeast India) and monsoon core zone (MCZ).
