No cold wave for five days as western disturbances take a break

Absence of western disturbance activity during the next five days will rule out cold wave conditions developing either over North-West India or Central India for as many days, an India Meteorological Department (IMD) update said early this (Friday) morning.

Moisture-laden western disturbances that cross in from the international border from Pakistan are responsible for triggering winter rain or thunderstorms over the plains of North-West India and snow along the hilly regions.

Anticyclone in charge

Cold wave conditions set in on the trail of a passing western disturbance from North-West or Central India to further East or North-East. Colder north-westerlies of Arctic origin fill the plains instead, and, being denser, sink to the ground bringing down the mercury level appreciably.

This process will be overseen by a seasonal anticyclone that moved into place at the lower level over North-West and adjoining Central India after the South-West monsoon exited the country. The anticyclone has clockwise movement of air around it, which guide the cold north-westerly winds.

Dry weather predicted

In this manner, the western disturbances have a major role to play in amplifying variously warm/wet weather and cold/dry conditions over areas that come under its footprint. The warmth is generated by the moisture and upward motion of air as against the sinking motion in the case of the anticyclone.

The IMD has forecast dry weather for most parts of North-West and Central India during the next five days since the western disturbance activity will be muted. No significant change in minimum temperatures is indicated, and hence, no cold wave conditions.

Wet over South Peninsula

Meanwhile, light to moderate rainfall may continue over parts of the South Peninsula during this period as the North-East monsoon negotiates the last month of the season. A helpful trough has taken shape in the easterlies blowing coastward, and runs from Sri Lanka to Andhra Pradesh along the Tamil Nadu coast.

Rain or thundershowers lashed many places over Odisha yesterday (Thursday); a few places over the plains of West Bengal, Rayalaseema, Tamil Nadu, Puducherry and Karaikal, while it was isolated over Coastal Andhra Pradesh, Yanam, South Interior Karnataka, Kerala and Mahe.

Mercury dip in East

Forecast until tomorrow (Saturday) said isolated to scattered light/moderate rainfall may occur over Coastal Andhra Pradesh, Yanam, Rayalaseema, Tamil Nadu, Puducherry, Karaikal, Kerala and Mahe during the next five days and over South Interior Karnataka and Telangana.

Night temperatures may fall by 2-3 degrees Celsius over most parts of the East India during the next three days. This will be accompanied by a gradual rise of the same by a similar order over Maharashtra. No significant change is seen over the rest parts of the country during the next four days.

An extended forecast valid from Wednesday to Friday next (December 15-17) said that scattered/fairly widespread light to moderate rainfall is likely over Tamil Nadu, Puducherry and Karaikal and isolated over Kerala, Mahe, South Interior Karnataka, Coastal Andhra Pradesh and Yanam.

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