IMD’s First Long-Range Forecast

April 15, 2022

The India Meteorological Department (IMD has issued a long-range forecast for the southwest monsoon season rainfall during the period June to September. The prediction has stated that rainfall will be normal this year.

Overview:

The long-range forecast of IMD is issued in two stages.
The first forecast is released in the month of April.
The second forecast is issued at the end of May.
In the country, for the period 1971 to 2020, the long period average seasonal rainfall is 87 cm.
In many areas of northern parts of the Indian Peninsula and adjoining central India along with the Himalayan foothills and some parts of Northwest India the rainfall will be normal.
Over many areas of Northeast India, southern parts of the South Peninsula, and some areas of Northwest India the rainfall will be below normal.

Forecast Summary

According to the forecast that has been released, in the country, the southwest monsoon seasonal rainfall will likely be normal i.e. 96 to 104 percent of the Long Period Average (LPA).

The forecast predicts that the rainfall in the country is likely to be 99 percent of the LPA and a model error of 5 percent on either side has been predicted.

Rainfall category

Less than 90 percent of rainfall falls under the ‘deficient’ category, below normal is categorized when it is 90 to 96 percent, normal is categorized when it is 96 to 104 percent, above normal is categorized when it is 104 -110 percent and excess is categorized when it is over 110 percent.

How was the forecast generated?

For generating the forecast, April’s initial conditions have been used. Also, the best climate models having the highest skills over the Indian monsoon region have been used for predicting the forecasts.

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