Rainfall over the country during the second half of the South-West monsoon season (August to September) is most likely to be normal. It will be with a tendency to be on the positive side of normal.
According to India Meteorological Department (IMD) Director General Mrutyunjay Mahapatra, monthly rainfall in August is most expected to be normal. It will range from 94 to 106 percent of the Long Period Average (LPA).
He was addressing during a virtual press conference. He announced the rainfall forecast for the second half of the season and August. For the period of August to September, the LPA for the country as a whole is 428.3 mm from 1961 to 2010.
This year, the IMD predicts rainfall to reach 95 to 105 percent of the LPA in August and September. According to the spatial distribution, below normal to normal rainfall is anticipated in many sections.
The country’s northwest, east, and northeast, while normal to above normal rainfall is most likely in most of peninsular India and nearby central India, he said.
“As the changes in the sea surface temperature (SST) conditions over the Pacific and the Indian Oceans are known to influence the Indian monsoon, IMD is carefully monitoring the evolution of sea surface conditions over these Ocean basins,” Mahapatra said.
The LPA of August rainfall for the country as a whole for the period 1961-2010 is 258.1 mm, according to the probabilistic forecast for August. The regional distribution of probabilistic rainfall forecasts for tercile categories (above normal, normal, and below normal) for August implies that below normal to normal rainfall. It is likely over much of central India and parts of northwest India.
Rainfall will most likely be average to above normal in most parts of peninsular India and the northeast.
By modifying the present two-stage forecasting technique, the IMD has adopted a new strategy. It will release monthly and seasonal operational forecasts for southwest monsoon rainfall over the country this year.
The new strategy is based on an existing statistical forecasting system a newly designed MME-based forecasting system. The MME method incorporates coupled global climate models (CGCMs) from many global climate prediction and research organizations. This includes the Monsoon Mission Climate Forecast System (MMCFS) model from IMD.
As a result, on April 16, IMD released the first stage forecast for the 2021 southwest monsoon seasonal (June to September) rainfall. IMD also released a monthly forecast outlook for June rainfall across the country. It updated a forecast on June 1 and a forecast for July rainfall on July 1.
IMD will issue a rainfall forecast for September 2021 towards the end of August or the beginning of September.
