The skies over interior Tamil Nadu cleared briefly on Monday, except Chennai and the surroundings over the northern coast, after the trough that connected the Comorin area (South-East Arabian Sea) with the cyclonic circulation over South-East Bay of Bengal collapsed. The truncated trough now connects the South-East Bay with the South-West Bay, off the Sri Lanka and Tamil Nadu coasts. 

Brief lull expected

This will provide a brief lull from intense thunderstorms that have hit the region over the past couple of days until a rain-driving low-pressure area, the first of the season, forms over the South-West Bay off the Sri Lanka coast in the next couple of days (by Wednesday). The India Meteorological Department (IMD) expects it to track to the North-West towards the Tamil Nadu-Puducherry coast, with a possible slight intensification during the subsequent two days (by Friday).

But the IMD has predicted strong winds with wind speeds of 45-55 kmph gusting to 65 kmph (of near-cyclonic strength), to prevail over the Tamil Nadu-South Andhra Pradesh coasts on Thursday and Friday. Fairly widespread to widespread light to moderate rainfall with isolated heavy falls will likely impact the Andaman and Nicobar Islands, which are forecast to continue on Tuesday. 

Isolated heavy rain likely

Fairly widespread to widespread light to moderate rainfall with isolated heavy falls, thunderstorms and lightning are likely over Tamil Nadu, Puducherry, Karaikal, Kerala and Mahe and South Andhra Pradesh from Friday. Isolated very heavy falls are also likely over Tamil Nadu, Puducherry and Karaikal on Friday. An extended outlook from the weekend hinted at the possibility of fairly widespread to widespread light to moderate rainfall over parts of the South Peninsula and over the Lakshadweep and Andaman and Nicobar Islands, with isolated heavy falls likely over Tamil Nadu and Kerala. 

Successor ‘low’ seen

Numerical model predictions from the IMD hint at the development of a successor ‘low’ after a parent circulation drifts in from the Malacca Strait-South China Sea to the Bay. It could intensify at least into a depression off the Sri Lanka-Tamil Nadu coasts by November 16, up to which forecasts are available. The US National Centres for Environmental Prediction tend to more or less agree, pointing to a ‘very rainy week’ ending November 15. Heavily endowed thunderstorms are seen massing up off the Sri Lanka-Tamil Nadu coast during the subsequent week beginning November 16. 

Western disturbances

Meanwhile to the North of the country, this week could likely prove wet and cold, with a rain and snow-producing western disturbance waiting over Afghanistan to move in to Pakistan and North-West India. A successor disturbance is expected to chug in and affect the region from Wednesday. The IMD has forecast fairly widespread light to moderate rainfall or snowfall over Jammu, Kashmir, Ladakh, Gilgit-Baltistan, Muzaffarabad and Himachal Pradesh, while it will continue to be isolated light to moderate over Uttarakhand from Wednesday to Friday. Isolated light rainfall to a drizzle is likely over North Punjab and North Haryana during the period and over North Rajasthan on Tuesday. 

Weather bloggers’ take

 

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