IMD forecasts a normal monsoon, in boost to India’s rural economy

India Meteorological Department (IMD) in its first monsoon forecast says rainfall will be 96% of long-period average with a 38% probability of a near-normal season

India will receive normal rains during the June-to-September southwest monsoon season, the government’s weather office said on Tuesday.

If the forecast holds, it will boost rural demand and also alleviate rural distress, especially in states such as Karnataka and Tamil Nadu which are reeling under the impact of drought.

Rainfall will be 96% of the long-period average (LPA) with a 38% probability that monsoon will be near normal, said K.J. Ramesh, director general of India Meteorological Department (IMD). He added that rains would be evenly distributed across the country.

IMD will update these numbers in June.

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The average rainfall over the past 50 years, or the LPA, is 89cm. IMD’s forecast of 96% rainfall comes with a model error of 5%. It is considered to be above normal when it is between 105% and 110% of the LPA.

Till last year, IMD used to forecast probabilities for different rainfall scenarios such as deficit, below normal, above normal, normal and excess. However, for this year, the weather office gave the probability of only ‘near normal’ rainfall.

“The 38% probability is assigned to the normal category. This is also the highest among other rainfall scenarios,” said an IMD official who did not want to be named.

At a briefing, IMD’s Ramesh said the forecaster used both the static and the dynamic models of forecasting, but the dependence is more on the latter.

“The worries of an El Niño occurring during the peak of the southwest monsoon season are lower compared to it hitting at the end of the monsoon season,” said D.S. Pai, director of long range forecast at IMD, Pune.

El Niño is a weather phenomenon caused by unusual warming in the Pacific Ocean, resulting in atmospheric changes, potentially leading to a poor monsoon.

The onset of monsoon kick-starts the sowing season for summer crops in the country. India receives 70% of its annual rainfall during this period, which irrigates over half of its rain-fed lands.

In 2016, the monsoon was normal at 97% of the LPA after two straight years of deficit. The normal monsoon last year aided a rebound in agriculture growth to 4.2% (2016-17) after a dismal 1.2% growth and 0.2% contraction seen in 2015-16 and 2014-15, respectively.