Bhubaneswar: The India Meteorological Department has forcast that the South West Monsoon will hit Kerala by 27th May this year. In a press release, the IMD has said that the onset of the southwest (summer) monsoon over Kerala will be four days earlier than its normal date of June 1 with a model error of ± 4 days.
It said that, advance of the southwest monsoon over Indian main land is marked by monsoon onset over Kerala and is an important indicator characterizing the transition from hot and dry season to a 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 1st June with a standard deviation of about 7 days. India Meteorological Department (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 6 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) upper tropospheric zonal wind over the east equatorial Indian Ocean, and (vi) Outgoing Long wave Radiation (OLR) over the south-west Pacific region.
In the Indian monsoon region, initial monsoon rains are experienced over south Andaman Sea and the monsoon winds then advance north-westwards across the Bay of Bengal. As per the normal dates of monsoon onset/progress, the southwest monsoon advances over the Andaman Sea around 22nd May. In association with enhanced cross equatorial winds, conditions are becoming favorable for advance of Southwest Monsoon into South Andaman Sea, Nicobar Islands and some parts of southeast Bay of Bengal, around 15th May, 2022. Past data suggest that there is no association of the date of monsoon advance over the Andaman Sea either with the date of monsoon onset over Kerala or with the seasonal monsoon rainfall over the country.