The India Meteorological Department (IMD) in its forecast has predicted that India is likely to have a 'near normal' monsoon this year. With global weather phenomenon El Niño bearing down monsoon rainfall, this year it will on the cusp of normal and below normal in the country. The IMD usually does not use the category 'near normal'. Under this category, the IMD has slotted rainfall between 96-104% of the long-period average, which is 890mm.
However, the 'normal' category, junked this year is also used for the same 96-104% category.
Quantitatively, monsoon rainfall this year will be 96% of the long period average, which is 890mm, based on 1951-2000 data. The forecast was issued with a model error margin of +/- 5%, IMD said. Even as they junked the 'normal' monsoon category in its forecast, IMD scientists and top officials vehemently denied that there was a shift in terminology.
"We are going to have a near normal monsoon. Weak El Niño conditions are prevailing and all models are suggesting that they will weaken further. We don't expect adverse effect of El Niño on monsoon. The IMD will closely monitor the conditions," said M Rajeevan Nair, Secretary, Ministry of Earth Sciences.
As opposed to IMD, private weather forecaster Skymet has predicted a below par monsoon at 93% quantitative rainfall over the long period average. Skymet based its forecast of a below normal monsoon on projections that indicated 80% chance of El Niño conditions between March and May.
"There is a consensus among meteorological agencies across the world that El Niño is likely to peak in July. However, the weakening of El Niño happens slowly and there is also discussion between agencies on how the effects will linger. The picture will become clearer in the next two months," said Akshay Deoras, PhD researcher, Department of Meteorology, University of Reading.
Talking about last year's forecast, Rajeevan said that IMD was not totally off the mark. "We gave a forecast of 97% and we had downgraded it due to conditions in Northeast. But, other parts of the country received good rainfall."
The forecast also stated that there was a 17% probability of a deficient monsoon, 32% probability of below normal monsoon, 39% of near normal monsoon, 10% probability of above normal monsoon and 2% probability of excess monsoon.
El Niño conditions develop when the sea surface temperatures over equatorial Pacific Ocean turn warmer over the central and east Pacific. Usually, it impacts Indian monsoon negatively, leading to deficient rainfall. However, the IMD scientists said that it does not have a direct relation to the Indian monsoon performance. IMD will have a clearer picture on the El Niño conditions in June and July.
Weather Watch
- During 1951-2018, there were 15 El Niño years
- 9 out of 15 yrs saw deficient rainfall (<90%)
- In two of the 15 years, monsoon rain was 100%
- El Niño conditions develop when sea surface temperatures over equatorial Pacific Ocean turn warmer over the central and east Pacific
