The India Met Department (IMD) has retained the outlook for ‘active’ to ‘vigorous’ monsoon conditions for Kerala and Coastal Karnataka over the next four to five days.

This will be marked by rainfall at most places and heavy to very heavy and extremely heavy falls at isolated places Kerala until Monday and over Coastal Karnataka mainly from Saturday to Monday.

Fairly widespread to widespread rainfall with isolated heavy to very heavy falls have been forecast also over South Interior Karnataka and Lakshadweep during the next four days.

Contrasting troughs

The 24 hours ending on Thursday morning saw rain or thundershowers at most places over Konkan, Goa, Kerala, Mahe, the Andaman & Nicobar Islands and Lakshadweep.

Heavy to very heavy rainfall was observed at a few places over Lakshadweep while it was heavy at isolated places over Haryana, Chandigarh, Delhi and Andaman & Nicobar Islands during this period.

Rains were confined to at a few places over Jammu & Kashmir, Himachal Pradesh, West Uttar Pradesh, Bihar, Chhattisgarh, the North-Eastern States, hills of Bengal, Sikkim, Coastal and Interior Karnataka, Odisha, Coastal Andhra Pradesh.

Isolated places over Rajasthan, Jharkhand, East Gujarat, East Uttar Pradesh, Madhya Pradesh, Assam, Meghalaya, Telangana, Rayalaseema, Tamil Nadu, Puducherry, Marathwada, Vidarbha, Punjab, plains of Bengal and Madhya Maharashtra also reported rain of varying amounts.

The main rain-generating features - offshore trough along the West Coast and the land-based trough from Rajasthan to the Bay of Bengal - presented contrasting pictures with respect to individual growth prospects.

Circulation in Bay

The offshore trough, which receives the monsoon moisture mopped up by South-Westerly winds over the Arabian Sea, continued to be weak and truncated lying from South Maharashtra coast to Kerala coast .

The trough deepens in tandem with the strength of the monsoon flows, and will expand in alignment along the entire coast from South Gujarat to Kerala, representing active monsoon conditions.

On the other hand, the IMD said the land-based trough from North-West Rajasthan dipping in a South-East direction to North-West Bay of Bengal would positively strengthen during the next four days.

It reflects also on the prospects of a likely low-pressure area forming in the Bay which will anchor one end of the trough while the other will be tethered to North-West or West Rajasthan.

A preparatory cyclonic circulation hung over the North-West and adjoining West-Central Bay and South Odisha, the IMD said in an evening update.

The land-based trough sets up the highway for monsoon flows from the Bay to race in into the country's farming heartland covering East India, Central India, West India and North-West India.

An extended outlook from Tuesday to Thursday has forecast widespread rainfall with scattered heavy to very heavy falls over Kerala, adjoining ghat districts of Tamil Nadu and Karnataka.

Published on July 18, 2019