A persisting cyclonic circulation and a narrow corridor of low pressure (trough) extending from the South Sri Lanka coast across Tamil Nadu towards the North Andhra Pradesh coast have combined to set off a wave of North-East monsoon rains along most of the eastern seaboard of India.

The trough is being pushed further to the west (towards and into the coast) by a phalanx of strong easterly winds packing thunderheads precipitating scattered to fairly widespread rainfall accompanied with thunderstorms, lightning wand heavy falls over Tamil Nadu, Puducherry and Coastal Andhra Pradesh on Wednesday and also on Thursday.

Successor easterly wave

India Meteorological Department (IMD) said that a successor easterly wave may wallop South-East Peninsular India (mainly Tamil Nadu) later during this week bringing scattered to fairly widespread rainfall, thunderstorms, lightning, and isolated heavy falls over Tamil Nadu and Puducherry on Saturday and Sunday and over Coastal Andhra Pradesh on Sunday.

An extended outlook from November 16 to 18 (Monday to Wednesday next) said that scattered to fairly widespread rainfall may persist over Tamil Nadu and adjoining parts of Coastal Andhra Pradesh and Kerala. Isolated to scattered rain is forecast over Rayalaseema and Lakshadweep.

Warmer nights likely

Meanwhile, the IMD also said that mainly easterly winds prevail over the entire country under whose influence minimum (night) temperatures may look up by 2-3 deg Celius over North-West India and by 2-4 deg Celsius over East, Central and South Peninsular India during next three days.

But an incoming western disturbance from across the international border may bring isolated to scattered light precipitation over North west India and adjoining Central India on Saturday and Sunday and fairly widespread to widespread precipitation with isolated heavy falls over Jammu & Kashmir and Ladakh.

An extended outlook here also (Monday to Wednesday) hinted the possibility of scattered to fairly widespread rain/snow over Jammu-Kashmir, Ladakh and Himachal Pradesh while it would be isolated rainfall over the plains of North-West India. Western disturbances are crucially important viewed from the angle of crucial rain for the winter crop in North India.