IMD sees extended cold weather for North, Central India

A lull in the movement of active western disturbances across North-West India and adjoining Central and West India will serve to further entrench cold wave conditions over parts of the region, and ground frost in others.

Western disturbances are crucial weather systems that help modulate the winter weather over these regions, producing alternating dry/cold or warm/moist weather depending on the time of their movement and intensity.

Biting Arctic cold

Western disturbances are by-products of the low-pressure band of westerly winds perambulating the globe at regular intervals, disrupted over India only through the annual monsoon season by the prevailing easterly winds from the Bay of Bengal.

During winter, they bring the biting Arctic cold from Europe and Central Asia into play over North-West, Central and West India and at times in the East as well but progressively reduced over Peninsular India.

The cold gets smothered only if the westerlies delve deep enough to the South over Afghanistan/Pakistan and mop up moisture from the North Arabian Sea and allows the system to warm up, setting up rain clouds as they fan into the Himalayas.

Cold spell prevails

Currently, a cold spell is active over North-West India and the adjoining geography, an India Met Department (IMD) update said on Thursday, with no movement of western disturbance forecast for the next 4-5 days.

Also read:Delhi likely to get four spells of dense fog; to affect flight traffic

Extended outlook indicates that these conditions might continue until the end of the month over the country, broken briefly by a circulation in the Bay of Bengal approaching the Tamil Nadu coast.

The IMD said on Thursday that a feeble western disturbance lay over North Pakistan and adjoining Jammu & Kashmir, moving eastwards across the northern parts of Jammu & Kashmir, too far away to be of any consequence for North-West India.

Cloudless skies

Under this scenario, it found no significant change in the prevailing wind pattern over the plains, which are currently westerly to north-westerly in direction. Minimum (night) temperatures may continue to prevail below normal by 3-4 Deg Celsius.

This is because clear and cloudless skies allow the Arctic air to fill the plains and get forced down to the ground level by the seasonal anti-cyclonic circulation (with descending motion of air, as against ascending in a cyclonic circulation).

Some parts of the plains of North-West and adjoining Central and West India might slip under cold wave and ground frost conditions during the next two to three days.

Meanwhile, in the South, a sea-based circulation (trough of low) approaching the peninsular India (initially the Tamil Nadu coast) may trigger rainfall of varying intensity from Saturday to Monday.

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