Withdrawal of the South-West monsoon is expected to pick up speed over the next few days, clearing the way for the North-East monsoon over the southern peninsula.

The ground is being set by the fading away of a remnant of Bay of Bengal cyclone Phailin over Jharkhand-Bihar, according to indications by various weather models.

Also of significance is the activity in the North-West Pacific/South China Sea just to the east, which is hosting two typhoons or tropical cyclones.

Of these, Typhoon Nari was negotiating the waters of South China Sea and headed west towards Vietnam where it is expected to make a landfall by Tuesday morning. West-bound storms in the South China Sea at this time of the year are known to herald the easterly winds across Thailand/Vietnam into the Bay of Bengal and help establish the North-East Monsoon. In fact, model outlooks suggest the Bay responding to the ‘rain pulse’ from typhoon Nari and the wind pattern becoming increasingly easterly during the next few days.

SWIFT WITHDRAWAL

Simultaneously, a helpful circulation in the West Arabian Sea away from the India coast and moving further away, could expedite the flow of easterlies across the peninsula. All this means that overstay of South-West monsoon would come to a swift end over the next few days and the North-East monsoon may announce its onset around the usual timeline of October 15-20.

An India Meteorological Department update said on Monday that rain and thundershowers would occur over many parts of the southern peninsula and Andaman and Nicobar Islands from Thursday.

vinson.kurian@thehindu.co.in

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