Weather: Tamil Nadu, Puducherry continue to be rain-deficit

All-India rainfall since October 1 (till November 13, Friday) now shows a deficit of eight per cent, within the ‘normal’ category as defined by the India Meteorological Department (IMD), but the embedded North-East monsoon over the South Peninsula continues to be in deficit.

The rainfall deficit over the main North-East monsoon territory of Tamil Nadu is 47 per cent; while it is 50 per cent in Puducherry; 35 per cent in Kerala; and a much larger 63 per cent in the Lakshadweep Islands. Exceptions are Telangana, Karnataka, and Andhra Pradesh.

In fact, these latter three states continue to enjoy a surplus carried over from the monsoon transition period (South-West to North-East). Telangana has a surplus of 58 per cent and Karnataka, 18 per cent while Andhra Pradesh has a slight deficit of eight per cent (in ‘normal’ category).

Rain, thunderstorm forecast

An IMD forecast said that scattered to fairly widespread rainfall accompanied with thunderstorm and lightning may continue over Tamil Nadu, Puducherry, Coastal Andhra Pradesh, Kerala and Lakshadweep area during next 4-5 days as a fresh easterly wave arrives over the South Peninsula.

Isolated heavy rain is likely over Tamil Nadu and Puducherry during the next five days and over Coastal Andhra Pradesh on Monday and Tuesday. Ahead of this, the prevailing rain-driving trough along the Tamil Nadu coast front-ended by a cyclonic circulation over the Comorin region to the South-South-West may weaken.

Western disturbance arriving

To the North of the country, an incoming western disturbance is expected to interact with prevailing easterly winds over the country to produce scattered to fairly widespread precipitation over the hilly terrains of Jammu & Kashmir, Ladakh, and Himachal Pradesh.

Isolated to scattered rainfall is forecast over Uttarakhand, Punjab, Haryana and West Uttar Pradesh on Sunday and Saturday while it would be isolated over the remaining parts of the plains of North-West India and adjoining Central India on Sunday. Isolated heavy falls may lash Jammu & Kashmir and Saturday and Sunday and Himachal Pradesh on Sunday.

Global model forecasts

Global forecasts give Tamil Nadu and Puducherry until December 12 to claw their way back and cut down the deficit, with the ongoing wet session likely to go on until November 22. This would be followed by a comparably calmer week into the month-end with likely normal rainfall.

The North-East monsoon may come back to life (though not as active as it currently is) yet agin into early December and may hold on as such for the first week to 10 days before plateauing to normal or even below normal. Activity would be confined to the fringes of the Bay of Bengal.

European model outlook

But a 46-day forecast for accumulated precipitation from the European Centre for Medium-Range Weather Forecasts (ECMWF) put parts of Coastal Andhra Pradesh and almost entire Tamil Nadu region on the positive side beginning from Kurnool in Andhra Pradesh.

This covers Chennai, Thanjavur, Madurai, Tirunelveli and Coimbatore district apart from the southern districts of adjoining Kerala. Normal rain is indicated for Karnataka, Telangana and the rest of Andhra Pradesh and even over adjoining parts of Maharashtra, per the ECMWF outlook.

Also falling under the surplus rain footprint during this period in interior Tamil Nadu is the Palayamkottai- Thoothukudi-Kovilpatti-Dindigul and the Udhagamandalam-Erode-Coimbatore belts extending to Malappuram-Palakkad and Kumily-Ernakulam in adjoining Kerala.

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