The excess rainfall regime over South Peninsula, including Tamil Nadu, is expected to sustain for another 10 days to at least until November 22, according to latest projections.

Apart from Tamil Nadu, coastal Andhra Pradesh, Rayalaseema, South Interior Karnataka and Kerala fall under this region.

Heavy rain outlook A short-term outlook in terms of rainfall given out by India Met Department is as follows:

Saturday: Heavy rain at isolated places over Coastal Andhra Pradesh, Rayalaseema, Tamil Nadu, Puducherry and Kerala.

Sunday: Heavy to very heavy rain at a few places over Tamil Nadu and Puducherry and isolated places over Coastal Andhra Pradesh and Kerala.

Monday: Heavy to very heavy rainfall at a few places in Tamil Nadu and Puducherry with extremely heavy rainfall at isolated places.

Heavy to very heavy rain at isolated places over Coastal Andhra Pradesh, and heavy over Rayalaseema, South Interior Karnataka and Kerala.

Not drying up It is not as if rains will dry up after November 22, according to a projection by the Indian Institute of Tropical Meteorology. Normal rains will continue over the region until December 2, up to which updates are available.

As already mentioned, the current wave of rain is prospering under benign conditions set up by a large trough of low pressure area covering the entire South and South-West Bay of Bengal.

It is within this trough that a core low-pressure area is developing, and is thought by a number of weather models including India Met Department to intensify into a depression to begin with.

This ‘low’ is expected to form over South-East Bay of Bengal, a good distance away from the Tamil Nadu coast, by Saturday.

Its typical West-Northwest course would take it closer first to the Sri Lanka coast, and subsequently to the Tamil Nadu coast. It is expected to grow stronger as it approaches the coasts.

Extended rainfall What is implied is that the rains already buffeting Tamil Nadu and Kerala will only grow in intensity and reach a crescendo by Monday/Tuesday when the likely depression approaches the Tamil Nadu coast.

Wind profile projections suggest that the system will empty itself near the Puducherry coast and will carry some punch with it as it negotiates the hinterland to the west-northwest (over Kerala and South Interior Karnataka).

Heavy to very heavy rains are forecast along the way traversed by the system, according to these projections. The trough of low pressure over the Bay of Bengal may weaken a bit after the system crosses but would still have enough left with it to trigger thundershowers at most places in the region until November 22.

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