In Fresh Monsoon Update, IMD Reasserts Its Previous Forecast — With Reduced Error Margin

Reasserting its previous forecast of 96 per cent of Long Period Average (LPA) rainfall for the upcoming monsoon season which commences from June 1, the India Meteorological Department [IMD] reduced the error margin from plus or minus five per cent to four per cent today, on May 26.

LPA is the average seasonal rainfall recorded between the period of 1971 and 2020, and is recorded as 87 centimetres.

“Quantitatively, the southwest monsoon seasonal (June to September) rainfall over the country as a whole is likely to be 96% of the LPA with a model error of ± 4%,” the IMD mentioned.

In contrast to IMD, Skymet, a private weather forecasting and agriculture risk solution company, had forecasted the seasonal southwest monsoon to be ‘below normal’ — 94 per cent of Long Period Average — this year. Skymet issued its monsoon forecast on April 10, a day before IMD’s forecast.

The updated forecast, which mentions ‘normal’ monsoon, has deepened the concerns for the section of the agrarian community which depends on rainfed irrigation.

Rainfed agriculture occupies about 51 per cent of the country's net sown area and accounts for nearly 40 percent of the total food production.

The five categories of probability forecasts for the Seasonal (June to September) rainfall over the country are as below:

The Met department noted that, “In June, below normal monthly rainfall is expected over most parts of the country except some areas of south peninsular India, northwest India, extreme north India and some isolated pockets of northeast India”.

“In June, above-normal monthly maximum temperatures are likely over most parts of the country, except for the extreme north and some parts of the southern peninsular India, where below-normal and normal temperatures respectively are likely,” it added.

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The updated forecast for the 2023 Southwest Monsoon season rainfall has been calculated by incorporating forecasts from different coupled global climate models based on the initial weather conditions in the month of May.

The IMD indicated neutral El Niño–Southern Oscillation [ENSO]- conditions across the equatorial Pacific Ocean with near to above average sea surface temperatures over most of the central and the east equatorial Pacific Ocean.

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In respect of spatial distribution of the monsoon seasonal rainfall, normal to above normal rainfall is likely over the most areas of south peninsular India, some areas of east central India and many areas of northeast and extreme north India. However, normal to below normal rainfall is likely over man y areas of northwest India and adjoining west central India, northern parts of the peninsular India and along the foothills of Himalayas.

These forecasts are available here.