The onset of the South-West monsoon over Kerala is likely to be delayed until June 7 with a model error of plus or minus four days, says the India Meteorological Department.

This could have a cascading effect on the arrival of the eagerly-awaited rains in the drought-hit areas of Karnataka, Andhra Pradesh and Maharashtra.

Normal date The normal onset over Kerala is June 1, which signals the arrival of the key South-West monsoon over the subcontinent.

BusinessLine had on April 13 reported that El Nino-related historical data suggest that the monsoon onset could be delayed by up to 10 days this year. Rains hit the Andaman Sea normally around May 20, with a standard deviation of about one week.

Depression watch The Met predicts the monsoon to set in over the Nicobar Islands, the South Andaman Sea, and parts of the South Bay of Bengal by Tuesday. The rains reach Sri Lanka next, followed by Kerala. This normally takes 10-12 days but will take more time this year, the Met has forecast.

Meanwhile, a low-pressure area over the South-West Bay of Bengal and adjoining Sri Lanka had intensified to become ‘well-marked’ on Sunday. It is expected to move north-west (towards South and South-West Tamil Nadu) and further intensify into a depression by Monday.

May intensify In the process, it will pull in strong flows into the South Bay of Bengal, leading to the onset of the monsoon over the Nicobar Islands and South Andaman Sea.

It is expected to move north-west and intensify into a deep depression (one step short of being called a cyclone) and cross the Tamil Nadu coast between Pamban and Nagapattinam on Tuesday morning.

For the next few days, heavy to very heavy rain has been forecast for parts of Kerala, Tamil Nadu, Puducherry, coastal and south interior Karnataka, Rayalaseema, south coastal Andhra Pradesh, and parts of the North-East States.

Squally winds reaching speeds of up to 70 km/hour have been forecast along and off the coast of Tamil Nadu from Sunday. Fishermen have been advised not to venture out into the sea.

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