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Weather: IMD issues depression watch over Bay, again

Vinson Kurian Thiruvananthapuram | Updated on November 29, 2020 Published on November 29, 2020

Clouds converge over the South Bay of Bengal as a low-pressure area forms over the South-East Bay and adjoining Equatorial Indian Ocean. It is expected to become a depression by Monday afternoon.   -  The Weather Company

South Tamil Nadu, Kerala to receive heavy rainfall

A low-pressure area has formed over the South Andaman Sea, adjoining areas of South-East Bay of Bengal and Equatorial Indian Ocean, almost the same region where very severe cyclone ‘Nivar’ had taken birth last week, and gone on to cross the Puducherry coast and neighbourhood a few days ago.

In what is being revealed as latent explosive activity around the Sumatra-South Andaman Sea region, the prevailing ‘low’ is also expected to concentrate into a depression by Monday afternoon, and may intensify further possibly into a cyclone, if the wind speed projections given out by India Meteorological Department (IMD) is any indication.

Prospects of rebuilding as storm

This system is predicted to move west-north-westwards and reach extreme North Sri Lankan and South Tamil Nadu coasts, involving back-to-back landfalls (Sri Lanka and South Tamil Nadu) by Wednesday, which would decide the strength with which it may be hit the South Tamil Nadu coast.

A landfall could slow it down and weaken it, but may rebuild as a storm if allowed to negotiate warm ocean waters again for some time.

This window may be too short in the instant case since the Pak Strait/Gulf of Mannar that separates South Coastal Tamil Nadu and Sri Lanka is a very narrow corridor. The track of the storm resembles that if very severe cyclone Ockhi of 2017, except that it had travelled more open waters to the South of Sri Lanka before re-curving to Lakshadweep and close to Kerala-Karnataka coasts.

Projected landfall area

But the brewing cyclone three years hence would still be able to retain its original intensity if the first landfall were to take place over the tapering extreme northern parts of Sri Lanka, and hit the Tamil Nadu coast to the South of Puducherry where predecessor very severe cyclone ‘Nivar’ had made the landfall.

Meanwhile, the IMD said that a remnant of the depression/would-be cyclone may emerge into the South-East Arabian Sea after crossing the extreme South Peninsula (extreme southern Tamil Nadu and Kerala) on Thursday, before moving west-north-westwards and away from the Kerala coast and re-intensifying again.

Heavy rainfall, squally weather

Forecast for today (Sunday) predicted that heavy rainfall over the Andaman & Nicobar Islands and thunderstorms with lightning over Kerala and Andaman & Nicobar Islands. Squally weather with wind speeds reaching 45-55 km/hr, gusting to 65 km/hr (almost depression strength) may prevail over the South-East and adjoining South-West Bay of Bengal and the South Andaman Sea.

Fishermen are advised not to venture into these areas.

Monday: Thunderstorms with lightning may break out over Kerala and Lakshadweep. Squally weather with wind speeds reaching 45-55 km/hr gusting to 60 km/hr is likely over South-West and adjoining South-East Bay of Bengal and the Gulf of Mannar.

Fishermen are advised not to venture into these areas.

Tuesday: The depression is expected to intensify twice over to become a cyclone with heavy to very heavy rainfall lashing South Tamil Nadu and South Kerala and heavy rain over Coastal Andhra Pradesh, Tamil Nadu, Puducherry and North Kerala.

Thunderstorms with lightning may be unleashed over Coastal Andhra Pradesh, Rayalaseema, South Interior Karnataka, Lakshadweep, Kerala, Tamil Nadu and Puducherry.

Squally weather with wind speeds reaching 65-75 km/hr, gusting to 85 km/hr (cyclone strength) may prevail over South-West Bay of Bengal and along and off the South Tamil Nadu coasts and 65-75 km/hr gusting to 85 km/hr along & off North Tamil Nadu, Puducherry and Kerala coasts, the Comorin Area and the Gulf of Mannar.

Fishermen are advised not to venture into these areas.

Rainfall to escalate by Wednesday

The projected cyclone would bring widespread rainfall over Tamil Nadu, Puducherry, Kerala, Lakshadweep, South Coastal Andhra Pradesh and South Rayalaseema on Tuesday and Wednesday.

Isolated heavy to very heavy rainfall with moderate thunderstorms and lightning is forecast over Tamil Nadu and Puducherry on these days, while it would be extremely heavy over South Tamil Nadu and South Kerala on Wednesday.

Isolated heavy falls with moderate thunderstorms and lightning is forecast also South Coastal Andhra Pradesh on Tuesday and Wednesday and over Rayalaseema, South Interior Karnataka and the Lakshadweep area on Wednesday.

An extended outlook from December 4-6 (Friday next to Sunday) highlights the possibility of light to moderate rainfall at most places over the South Peninsula and the Andaman & Nicobar and Lakshadweep Islands (the Bay of Bengal and the Arabian Sea on either side of the peninsula). Isolated heavy falls may break out over these islands.

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Published on November 29, 2020
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