Agri Business

South-West monsoon withdrawal line crosses Vindhyas to reach final leg

Vinson Kurian THIRUVANANTHAPURAM | Updated on October 14, 2019 Published on October 14, 2019

Withdrawal line of the South-West monsoon has raced southward on Monday to dip into Peninsular India beyond the significant milestone of the Vindhyas, and is expected to cover the rest of the peninsula over the next two days.

Simultaneously, the stage have been set for the North-East monsoon with the change in wind directions, a process already under way in parts of the South-East Peninsula (mainly Tamil Nadu coast).

Fast-paced exit

In its update on Monday afternoon, India Met Department (IMD) said the the South-West monsoon has further withdrawn from remaining parts of North Arabian Sea, some parts of Central Arabian Sea and remaining parts of Gujarat and Madhya Pradesh.

It also covered some parts of Konkan, Madhya Maharashtra, Marathwada, and entire Vidarbha (in Maharshtra) and some parts of South India as the withdrawal showed signs of urgency over the past couple of days.

Parts of Chhattisgarh, some parts of Odisha, entire Jharkhand, Bihar and hills of Bengal, Sikkim, some parts of the plains of Bengal, entire North-East India and some parts of North Bay of Bengal have also bid the South-West monsoon an adieu.

The withdrawal line on Monday passed through Diamond Harbour, Bangriposhi (Odisha), Sundargarh, Dhamtari, Ramagundam, Nanded and Alibagh across the states of Bengal, Odisha, Chhattisgarh, Telangana, and Maharashtra.

The IMD assessed that conditions are becoming favourable for further withdrawal from some more parts of the North Bay of Bengal, most parts of East and Central India, some more parts of South and West India during the next two days.

Read the IMD bulletin here

Reversal of winds

Alongside, reversal of surface and low level winds from westerly to easterly has commenced over the south-eastern parts of Peninsular India (mainly Tamil Nadu) and the easterly wind regime is likely to strengthen during the next few days.

With the gradual withdrawal of the South-West monsoon over the northern and central parts of India, conditions are becoming favourable for commencement of the North-East monsoon around Thursday, the IMD said, reiterating an outlook already declared.

In anticipation, scattered to fairly widespread rainfall with isolated heavy falls accompanied by thunderstorms and lightning are expected to invade parts of the South Peninsula during the next four to five days.

Heavy rainfall has already been recorded at isolated places over Coastal Andhra Pradesh, Tamil Nadu and South Interior Karnataka during the 24 hours ending on Monday morning, the IMD said.

Meanwhile, unlike in the past, the IMD has not yet indicated in its forecast statement any low-pressure area/depression taking shape to either side of the peninsula (the Arabian Sea and the Bay of Bengal) to herald the arrival of the season this year.

Weather system likely

But its wind-profile projections show a build-up from the South-East Bay of Bengal and the adjoining East-Indian Ocean over the next few days eyeing the North-East Sri Lankan and Gulf of Mannar/South-East Tamil Nadu coast.

It resembles an easterly wave,  which is a fast-moving low-pressure wave across the Bay of Bengal and is frequent during the North-East monsoon, though known to travel along a straight line. Some of the 'rain heads' packing the wave have gone on in the past to become low-pressure areas, depressions, even cyclones. But no such intensified form of weather is being forecast this time round.

But the wind-profile graphics proceed to hint at some development off the Tamil Nadu coast around October 24 by when the North-East monsoon would have earned its spurs over the South Peninsula.

A weather tracker featured by the Climate Prediction Centre of the US National Weather Service also points to a circulation developing here and gaining some traction as well.

 

It is shown as affecting the North-Coastal Tamil Nadu ad South Coastal Andhra Pradesh initially, before being guided off and along the East Coast towards Bengal even as its 'embers' spark rainfall over the East Interior Peninsula.

A splinter is forecast to cross West across Coastal Andhra Pradesh into Rayalaseema, North Interior and adjoining Coastal Karnataka to touch off some activity in the Arabian Sea as well.

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Published on October 14, 2019
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