India Meteorological Department (IMD) on Friday made a downward revision in its rainfall forecast for the upcoming monsoon season, saying the country was expected to receive rains that was only 90 per cent of the long period average. Last month, in its initial long-range forecast, the IMD had said the country was expected to receive 92 per cent rains during the season.
The IMD puts out rainfall forecast for the June-September monsoon season in the middle of April every year, and then updates it towards the end of May.
The 92 per cent prediction in April this year was the lowest forecast made by IMD at the initial stage in more than 20 years. It is now true for the May forecast as well. Never, in the last 20 years at least, has IMD’s updated forecast in May predicted such low rainfall.
In the last 20 years, there have been three occasions when the monsoon rainfall has been less than 90 per cent – in 2009, 2014 and 2015. This year is all set to join that group.
IMD’s updated forecast on Friday showed there was a 60 per cent chance that the seasonal rainfall would be below 90 per cent of the long-period average, or LPA. The LPA is the average rainfall over the 50-year period 1971-2020, which is considered the baseline, or normal.
The IMD did not say what prompted the downward revision in its forecast, but an improved assessment of the emerging El Nino in the equatorial Pacific Ocean, and that of the Indian Ocean Dipole could have been the possible reasons. Since its previous forecast in April, more information about the emerging El Nino has become clear. El Nino, a largescale ocean-atmospheric interaction in the equatorial Pacific Ocean that influences weather patterns worldwide, is known to suppress rainfall over the Indian region. There are predictions that this year’s El Nino, which could persist well into the next year, could be one of the strongest ever.
IMD said the El Nino was expected to be weak in June, moderate in July and August and strong in September. This would mean that most of the monsoon season would pass off when the El Nino phase is weak or moderate. However, its actual impact on the rainfall cannot be quantified.
The Indian Ocean Dipole (IOD) is a similar phenomenon in India’s vicinity, and it too has an influence over the monsoon rainfall. IMD’s earlier assessment was that the IOD would transition from a neutral state to positive state during the monsoon season, which could counter some of the effects of the El Nino. But on Friday, the IMD said IOD was likely to remain neutral through the entire monsoon season.
Friday’s forecast means India could be headed for its driest year in the last one decade at least. The monsoon rains account for nearly three-quarters of India’s annual rainfall, and are extremely critical for agriculture, electricity generation, drinking water purposes and industrial use. The rains during this season fill up the reservoirs which serve the water needs of the country through the rest of the year.
The lack of rains is also expected to push the temperatures up. IMD said the country was expected to receive less than 92 per cent rains in the month of June. It also said that temperatures in most parts of the country in this month are likely to be above normal. The number of heatwave days are also expected to be at least 2-3 days longer, particularly in the northwest region comprising western Uttar Pradesh, Punjab, Haryana and .
