Mint Explainer: Understanding IMD's September rainfall projection
New Delhi: Southwest monsoon is expected to revive in September, with rainfall seen normal during the month in the range of 91-109% of the long period average of 167.9 mm, the India Meteorological Department (IMD) has forecast. This comes after the country experienced its driest August since 1901. Mint delves into the projection and what it means for the country's overall rainfall activity.
A. While presenting rainfall and temperature forecast for September, IMD chief Mrutyunjay Mohapatra said, “Precipitation in September is expected to be normal ranging between 91 and 109% of long period average (LPA) of 167.9 mm. Normal to above normal rainfall is most likely over many areas of northeast India, adjoining east India, foothills of the Himalayas and some areas of east-central and south peninsular India.
The below-normal rainfall is most likely over most areas of the remaining parts of the country." A. The standard error margin for September is typically more than other three months at +/- 9%. Even if rainfall in September is on the higher side, the June-September rainfall average is expected to be below normal for the whole season.
As of now, rains have been 10% below normal for the whole country, with August recording a 36% deficit. August receives 254.9 mm of rainfall, accounting for around 30% of total monsoon showers. At the upper end of the IMD's projection (109% LPA), September could receive a maximum of 183.01 mm rainfall.
When added to showers received during June-August, at 629.7 mm, the season's total could be 812.71 mm, which is 93.6% of LPA. The weather bureau defines rains at 90-95% of LPA of 868.6 mm as “below normal" and 96-104% as “normal". IMD’s forecast in May, based on both dynamical and statistical
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