The South Peninsula is slipping under cover of heavy to very heavy rainfall as weather systems promise to build up over the seas on either side - the Arabian Sea and the Bay of Bengal - over the next few days.

Preparatory cyclonic circulations have already sprung up over the Lakshadweep-Maldives area (Arabian Sea side) and off the Tamil Nadu coast and adjoining Sri Lanka (Bay of Bengal side).

LOW-PRESSURE AREA

The India Met Department (IMD) has put out an alert for formation of a low-pressure area, to emerge from the cyclonic circulation over Lakshadweep-Maldives by the weekend.

This is forecast to become a depression in the subsequent 24 hours, but most global models surveyed expect its eventual intensification into a tropical cyclone.

Some of them indicate a north-west track for the system towards the Oman coast, but not all are convinced. In fact, some see a northward track eyeing the South Pakistan-Gujarat coast in India.

The US National Weather Services was the first to pick the Oman track, but it was also the first to reassess it lately to the Karachi-West Gujarat coasts.

The US Navy global environmental model and the UK Met model, too, agree with the outlook that the prospective cyclone may not go the distance to touch base over the Oman coast.

TRACK NOT FINAL

It could be influenced by two intervening atmospheric systems - movement of a westerly trough across West-Asia and Pakistan, and a likely weather system back home in the Bay of Bengal.

The IMD's extended outlook also portends to the movement of a westerly trough, with a limb extending into the North Arabian Sea that could hold the cyclone in its tracks.

This 'limb' could scoop up the system from over the mid-Arabian Sea and put it in line with the movement of its parent - the westerly trough - and force the cyclone to recurve.

Alongside, a system shown as developing over the Bay (some models indicate a depression) could induce a pull on the cyclone, since they are linked by the same westerly wind regime along their southern flanks.

Weather models have put the preparatory cyclonic circulation lying off the Tamil Nadu and Sri Lanka coasts, and potential easterly waves from across the Bay, under close watch.

MONSOON WITHDRAWAL

Meanwhile, up North, conditions are favourable for further withdrawal of the South-West monsoon from remaining East Uttar Pradesh; most parts of Madhya Pradesh; Gujarat; the North Arabian Sea; and some parts of Bihar, Jharkhand and Chhattisgarh by tomorrow.

The IMD said Tamil Nadu and Kerala are likely to witness fairly widespread rain/thundershowers, with heavy/ very heavy rains at isolated places during the next four days.

Isolated to scattered thundershowers are also likely over parts of Maharashtra during the next two days. Meanwhile, friendly south-easterly to easterly winds have started blowing across the South Peninsula under the influence of the cyclonic circulation off Tamil Nadu-Sri Lanka.

The IMD wind profile maps show that the easterly wind regime, though weak in strength, has established from the tip of the South Peninsula, right up to coastal Andhra Pradesh.

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