Private forecaster Skymet Weather has in its latest forecasts suggested that the South-West monsoon might keep its date with the Andaman & Nicobar Islands, while being slightly delayed and sluggish during its onset over the mainland, along Kerala.

The onset dates are May 22 for the Bay Islands and June 4 for Kerala, Jatin Singh, Managing Director, Skymet Weather, told BusinessLine . Skymet is holding on to its outlook of 93 per cent in terms of overall monsoon performance, for now.

‘Good auguries’

“We do not think the forecast warrants a rethink unless there is are rapidly devolving or collapsing El Nino conditions in the Equatorial Pacific,” Singh remarked when reminded of the latest update from the Australian Bureau of Meteorology (BoM).

The BoM said on Tuesday that it has downgraded its outlook from ‘El Nino alert’ to ‘El Nino watch,’ while retaining a 50 per cent chance for the eventuality. It also cited emerging model convergence on a positive Indian Ocean Dipole (IOD).

The IOD mimics weather-altering El Nino-La Nina phenomena in the Indian Ocean. Its positive phase represents warming up of the West Indian Ocean relative to the East, and is thought to be a monsoon enabler.

While agreeing that these are good auguries, Singh, however, said that, from his experience, he has seen that the strength of the El Nino does not necessarily correlate with that of the monsoon. By the BoM’s own admission, despite the downgrading, there is a 50 per cent chance of El Nino developing later this year, which is still double the normal likelihood. “We need to take a close watch on the situation as it evolves,” Singh said.

Monsoon rains hit the Kerala coast usually a fortnight after calling in at the Bay Islands, en route Sri Lanka, where they usually make a pit-stop during the last week of May. But there is at least one global model (NCEP-GFS) that suggests that the monsoon might run into a rogue circulation in the Arabian Sea. Singh said he, too, is tracking the forecast on these lines. This circulation may take shape over the East-Central Arabian Sea, intensify, and chart a course away into the open waters towards Yemen/Oman.

This is a familiar track that systems forming in the Arabian Sea are known to take, often intensifying as powerful cyclones, though there are no forecasts yet of such an eventuality. The net effect is that the monsoon onset over Kerala gets delayed the rogue system dies out and the seawaters regain kinetic energy to rustle up the moisture for the onset.

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