An expected strengthening of easterly wave activity across the Bay of Bengal would revive the North-East monsoon yet again, signaling a wet spell for the best-known easterly wave playground comprising the island nation of Sri Lanka and the States of Tamil Nadu and Kerala in South Peninsular India.
In fact, Sri Lanka may get hit from Tuesday, as per global model projections. The Sri Lankan Meteorological Department has predicted several spells of showers over the Northern, North-Central, Eastern and Uva and Provinces from as early as Monday afternoon.
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Pilot showers over Lanka soon
The India Meteorological Department (IMD) saw scattered to fairly widespread rain/thundershowers over Tamil Nadu, Puducherry, Karaikal, Kerala, Mahe and Lakshadweep from Wednesday to Friday. Isolated heavy falls are also likely over Tamil Nadu, Puducherry and Karaikal during this period.
An extended outlook valid from Saturday to Monday hinted at the possibility of scattered to fairly widespread rain/thundershowers with isolated heavy falls over Tamil Nadu, Puducherry, Karaikal, Kerala, Mahe and Lakshadweep, and breaking afresh over upstream Andaman & Nicobar Islands.
To the North-West of the country, a winter-modulating western disturbance that caused heavy rain/snow over the hills and parts of adjoining plains on Monday morning over North Pakistan and adjoining Punjab, has weakened, letting in colder north-westerly winds into the region.
Cold, denser air over ground
In this manner, the warmth associated with clouding and moisture of a western disturbance from the ascending motion of air has been replaced with colder and denser air that sits over the ground, bringing to bear the frigid conditions in the upper air. Cloudless skies only aggravate the night temperatures.
The IMD expected that minimum (or night) temperatures to fall by 3-5o Celsius over most parts of North-West India during the next four days. No significant change in minimum temperatures is expected over most parts of Central and East India during next two-three days, after which they will also fall.
‘Cold day to severe cold day’ conditions have been warned of at a few places over Punjab until Tuesday and ‘cold day conditions’ over Haryana, Chandigarh and North-West Rajasthan. A ‘cold day’ is declared when maximum (day) temperature is less than or equal to 16o Celsius.
Fresh western disturbance
The arrival of a fresh western disturbance along can break the cold spell, and the IMD has already located an incoming one over Afghanistan and neighbourhood. Its moisture-carry, associated clouds, and ascending air would once again set up heavy snow or rain/thundershowers over the hills and plains and drive away the cold.
Meanwhile, a cyclonic circulation from an erstwhile low-pressure area over the South Arabian Sea persisted on Monday. However, a trough originating from it to South-West Madhya Pradesh across South Gujarat coast, and responsible for unseasonal rain over parts of Gujarat, Madhya Pradesh and Maharashtra over the past few days, has weakened.