E-Paper
Monsoon to arrive in Kerala on May 26: IMD
The advance of the southwest monsoon over the Indian mainland is marked by monsoon onset over Kerala and is an important indicator.
Monsoon is likely to set in over Kerala on May 26 with a model error of ±4 days, India Meteorological Department (IMD) has said on Friday. The normal date for monsoon arrival is June 1. Last year, monsoon rains arrived over Kerala on May 24.
IMD’s extended range forecast shows extensive rain along the southern parts of the west coast between May 14 to May 28.
The advance of the southwest monsoon over the Indian mainland is marked by monsoon onset over Kerala and is an important indicator characterizing the transition from the hot and dry season to the rainy season.
As the monsoon progresses northward, relief from scorching summer temperatures is experienced over the areas. Southwest monsoon normally sets in over Kerala on June 1 with a standard deviation of about 7 days.
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Date on monsoon
IMD has been issuing operational forecasts for the date of monsoon onset over Kerala from 2005 onwards. An indigenously developed state-of-the-art statistical model with a model error of ± 4 days is used for the purpose.
The six predictors used in the models are; i) minimum temperatures over north-west India, ii) pre-monsoon rainfall peak over south Peninsula, iii) Outgoing Long wave Radiation (OLR) over south China Sea, (iv) lower tropospheric zonal wind over southeast Indian ocean, (v) Outgoing Long wave Radiation (OLR) over the south-west Pacific region, and (vi) Lower tropospheric zonal wind over Northeast Indian Ocean. OLR is the total radiation going to space emitted by the atmosphere, or the extent of cloudiness.
Seasonal models have predicted an El Nino climate pattern will form between May and July this year and could be the strongest on record.
In India, an El Nino is associated with a harsher summer and weaker monsoon. Monsoon rainfall over the country is likely to be below normal at 92% of long period average (LPA) with an error margin of +/-5%, IMD has said in its first stage long range forecast for monsoon season.
The LPA of the seasonal rainfall over the country as a whole during 1971-2020 is 87 cm.
The spatial distribution suggests that the below-normal seasonal rainfall is most likely over many parts of the country except some areas over Northeast, Northwest and South Peninsular India, where normal to above-normal rainfall is likely.
