In a day of fast-paced developments, the well-marked low-pressure area over South-West and adjoining West-Central Bay of Bengal off the North Tamil Nadu-South Andhra Pradesh coasts of (Thursday) morning has concentrated into a depression.

Lying over South-West Bay off the North Tamil Nadu coast, the depression was located lay about 310 km South-East of Chennai and 290 km East-South-East of Puducherry, and 270 km East-North-East of Karaikal.

Extremely heavy rain

Strong easterly flows kicked up by the depression have triggered heavy to very rains over North Coastal and North Interior Tamil Nadu, Puducherry and Marakanam punctuated by extremely heavy rain, Chennai weather bloggers tweeted.

In another tweet, heavy rain is reported from the Cuddalore area, with the depression ‘breathing fire’ under a favourable environment.

It is expected to move to the West-North-West track and cross the North Tamil Nadu and adjoining South Andhra Pradesh coasts around Chennai by early tomorrow (Friday), a day later than it was originally thought to make landfall.

Double whammy for Chennai

For the second time and week-on-week, that depression comes calling on the rain-weary Chennai coast with its accompaniment of heavy to very heavy rain and extremely heavy rainfall.

Many parts of Tamil Nadu, including Chennai, have been receiving heavy rain over the last couple of days under a sustained barrage of easterly winds from the Bay.

A counterpart weather system (‘low’) loitering over the Arabian Sea to the other side of the peninsula only helped with the process, acting in tandem with the Bay ‘low’ to pull in the moisture-laden easterlies into the Tamil Nadu and South Andhra Pradesh coasts. Even the Arabian Sea ‘low’ is tipped to intensify a round, driving the North-East monsoon to another peak.

Arabian Sea ‘low’

In forecast valid for today (Thursday), India Meteorological Department (IMD) has said that light to moderate rainfall will occur at most places, heavy to very heavy rainfall at a few places, and extremely heavy falls at isolated places over Tamil Nadu, Puducherry and Karaikal as the depression draws nearer to the coast.

Heavy to very heavy rainfall may occur at a few places and extremely heavy falls at isolated places over adjoining districts of Rayalaseema, while it will be heavy to very heavy over South Coastal Andhra Pradesh and South Interior Karnataka.

Heavy rain on Friday

As for tomorrow (Friday), light to moderate rainfall is likely at most places and heavy to very heavy over Tamil Nadu, Puducherry, Karaikal and Coastal Andhra Pradesh as the depression hits the last miles and makes the landfall around Chennai. Heavy rainfall is forecast at isolated places over Rayalaseema and Karnataka.

Meanwhile, the US National Centres for Environmental Prediction indicates that the easterly wave will keep the pot boiling along with Sri Lanka and adjoining Tamil Nadu coast till the end of the month (November), delivering varying amounts of rainfall, with the highest spells unfolding likely over the South Tamil Nadu coast. Extended predictions of the IMD tend to agree.

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