Agri Business

Bay of Bengal may toss up fresh circulation by weekend

Vinson Kurian Thiruvananthapuram | Updated on September 21, 2021

Ensuing rains will further delay monsoon withdrawal

A fresh rain-driving cyclonic circulation is likely to form over East-Central and adjoining North-East Bay of Bengal by this weekend (Saturday) and reach the Odisha coast, seemingly the favourite landfall area for circulations and low-pressure areas originating in the Bay in recent times, in the subsequent two days.

It would spawn a fresh spell of heavy rainfall, likely over Odisha and adjoining areas on Saturday, according to an extended outlook from the India Meteorological Department (IMD) for the three days from Sunday to next Tuesday. Fairly widespread to widespread rainfall is likely over East India (Odisha and plains of West Bengal), Central India and the Andaman and Nicobar Islands.

‘Low’ forms over East

To the West, fairly widespread to widespread rainfall is forecast over East Rajasthan and Gujarat from other rain systems, while it would be scattered to fairly widespread over the South Peninsula, North-East India and along the West Coast, and isolated to scattered elsewhere.

Monsoon may end at lower end of normal, says IMD

This is even as the previous day’s cyclonic circulation emerging from the Bay concentrated into a low-pressure area this (Tuesday) morning and lay perched over the southern parts of the plains of West Bengal. As if on cue, an existing ‘low’ over North-West India weakened into a cyclonic circulation and lay over East Rajasthan and neighbourhood, triggering showers locally.

More rains for East Rajasthan, West MP

An outlook for the rest of the week said fairly widespread to widespread rain with isolated heavy falls may lash East Rajasthan and West Madhya Pradesh for the next five days; over East Madhya Pradesh and Vidarbha until Thursday; and Chhattisgarh, Madhya Maharashtra, Marathwada, Konkan and Goa until Wednesday (tomorrow); and over East Gujarat on Wednesday.

Active monsoon spell from next week as Bay hosts back-to-back ‘lows’

Scattered to fairly widespread rainfall with isolated heavy falls is forecast over Uttarakhand for the next five days while fairly widespread to widespread rainfall with isolated heavy falls may break out over Odisha and plains of West Bengal today (Tuesday), the IMD said.

Delays exit, says Skymet

Private forecaster Skymet Weather, in a status update, observed that monsoon 2021 has already outlived its official withdrawal date from West Rajasthan — namely, September 17 (reset from September 1). The westernmost posts of Jaisalmer and Barmer recorded decent showers as recently as Monday.

The stipulated withdrawal from extreme West Rajasthan had so far been estimated to begin from September 1. This was revised last year and the corrected date for the last outposts of Rajasthan is now September 17. Withdrawal dates have been shifted by 7-14 days across most parts of the country, including the national capital, where the new date is taken as September 25, Skymet Weather said.

Variabilities on show

Variability of monsoon withdrawal is as large as it is during onset. The difference is that withdrawal is always retrospective while the onset is declared on a real-time basis. The onset dates have been reset based on past data from 1961-2019 and withdrawal dates on data sets during 1971-2019.

In 2019, the monsoon withdrawal began late from October 9 and finished in the shortest record time of eight days on October 17. In 2020, the process started late yet again, on September 28, and the monsoon is set to complete a hattrick this year with the withdrawal behind schedule already.

The withdrawal process is complete as the line sweeps past the South Peninsula by October 15, allowing the easterly wind regime to establish, leading to the onset of the North-East monsoon (winter monsoon or return monsoon) over the region in the subsequent five days to a week’s time.

Published on September 21, 2021

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