A fresh low-pressure area has formed over south Andaman Sea, an update by India Met Department said this afternoon. It is expected to strengthen a round and become well-marked by Tuesday.

Birth of the ‘low’ also meant the premature death of a persisting well-marked counterpart over west-central Bay of Bengal off the coast of Andhra Pradesh.

Remainder whirl The sea-based could not make it to the coast. Only a remainder circulation hovered higher in the atmosphere above the sea, the Met said. The parent system was done in by the lower sea-surface temperatures nearer to the coast making for cool to cooler waters.

Cool water prevents evaporation from taking place and thus cuts off moisture feed into the system. Moisture is the fuel that makes the storm engine hum and sustains it. Also, wind shear values (sudden shifts in wind direction and strength with height) were tending to be high along the coast with a western disturbance approaching from the opposite direction.

Rains for TN These conditions may prevent the new ‘low’ from achieving traction as a strong weather system. Indications are that the system may seek out warmer waters along the Sri Lankan coast for a landfall.

Thus, it may avoid the Tamil Nadu-Andhra Pradesh coasts where the waters have cooled down to negative values (less than threshold temperatures of 28 deg Celsius for systems to sustain).

But these coasts may expect rain or showers over the next couple days from the outer wind bands of the incoming weather system. The Met has forecast heavy rain along the Tamil Nadu coast and progressively into the interior tomorrow and day after.

Rains may grow over south coastal Andhra Pradesh, Rayalaseema and north Tamil Nadu on Thursday and Friday. They may also extend to Karnataka and Madhya Maharashtra.

May break spell The incoming spell of rain is expected to break the lull in the North-East monsoon rains during the last week when even the Tamil Nadu Met subdivision registered a deficit of 54 per cent.

The deficit is worse with neighbours – 99 per cent in north interior Karnataka; 97 per cent in south interior Karnataka; and 87 per cent in Rayalaseema. Kerala was relatively better off with a deficit of 24 per cent.

The rest of the country didn’t fare much better either with all-India deficit for the week ending on October 31 at 78 per cent. Even for the season (October 1 to November 5) for which statistics are available, the overall rain figures for the country tossed up a deficit 30 per cent.

Tamil Nadu provides an exception having recorded excess rainfall of 23 per cent. Kerala was next best with 16 per cent (classified as normal). The rest of peninsula is variously under deficit.

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