Amid fears of a subdued monsoon this year due to a developing El Nino condition over the Pacific Ocean, the India Meteorological Department (IMD) on Monday said that rainfall as a whole during the four-month monsoon season would be ‘near-normal’.
In the first long-range forecast for this season, the IMD said rainfall was likely to be 96% of the long period average, or LPA. The LPA, defined as the average of monsoon rainfall over a 50-year period between 1951 and 2000, for the country is 89 cm.
The IMD also said the possibility of rainfall being excessive or ‘above normal’ was very low. The forecast of 96% is at the lower end of the band in which rainfall is classified as ‘normal’.
“The good news is that 2019 will have a near normal south west monsoon seasonal rainfall between June-September of 96% of the long term average, with a model error of plus or minus 5%,” M Rajeevan, Secretary, Ministry of Earth Sciences, said at a press conference.
While there are several factors that influence the Indian monsoon, the surface temperature in equatorial Pacific Ocean is among the most important. As of now, waters in that region of the Pacific Ocean, off the west coast of South America, are slightly warmer than normal, a condition called El Nino, that is known to suppress rainfall over India during the monsoon season.
But Rajeevan said El Nino was not too big a concern as of now. “There are prevailing conditions of a weak El Nino, but we don’t believe this will affect the monsoon adversely. In any way, there is no established one-on-one correlation between El Nino and the Indian monsoon. The sea surface temperature conditions over the Pacific and Indian oceans are being monitored continuously,” he said.
“Overall, the country is expected to have well-distributed rainfall which will be beneficial to Indian farmers during the Kharif season,” he said.
IMD Director General K J Ramesh, however, said the monsoon could have a sluggish start due to El Nino. “During the monsoon months, we expect El Nino to weaken and it should, therefore, not have adverse impact on rainfall. There, however could be some impact on the monsoon from El Nino in the earlier weeks of June, so the rains could be sluggish at this point,’’ he said.
Rajeevan even went on to predict the likely time of onset of monsoon over the Indian sub-continent, something that the IMD usually announces only in the middle of May. “We expect the onset of monsoon to take place by mid-May. IMD will issue the second stage monsoon forecast during the first week of June,” he said.
The Indian monsoon season begins with the onset of monsoon rainfall over Kerala sometime around June 1. The Andaman and Nicobar Islands start getting rains from the third week of May.
Last year, rainfall was both below average as well as less than forecast. India as a whole received 91% of the LPA last year while IMD had forecast that it would get 97% rains. The distribution of rainfall was also erratic, with some parts of the country experiencing extreme rainfall and flash floods.
“We were not wrong in our prediction last year. We did, however, fail miserably in predicting for the North Eastern region which received 78% LPA as opposed to the 93% that was forecast. The North Eastern region has never dropped below 80% rainfall, so this was unexpected,” Rajeevan said.
Ramesh, meanwhile, said the IMD had begun forecasting as well as disseminating information on thunderstorms from last year. “We disseminate information 24 hours in advance when a thunderstorm is expected to the district. We have recently started forecasting lightning as well and will soon be disseminating this forecast to the districts,” Ramesh said.