The Hindu Business Line : Bay ‘low’ materialises, seen tracking west

Thiruvananthapuram, Dec. 3 India Meteorological Department (IMD) has said the anticipated low-pressure area has materialised over the southeast Bay of Bengal on Wednesday evening, which is expected to chart a westward course.

The US Naval Research Laboratory at Monterey estimated winds buffeting the system, initially tagged ‘96B Invest,’ had logged up to 20 knots (37 km/hr) at 6.30 pm Indian Standard Time.

Heavy rains have been forecast for the Andaman and Nicobar Islands over the next two days. Rain or thundershowers have been also forecast at isolated places over Kerala, Karnataka, Rayalaseema, Lakshadweep, Konkan and Goa. Extended forecasts up to Monday say that scattered rainfall activity is likely to persist over the south peninsula and fairly widespread rainfall activity over Andaman and Nicobar Islands.

WESTERLY SYSTEM

It is also becoming increasingly clear that the Bay ‘low’ would have to contend with a moderately strong western disturbance and associated band of westerlies. They are forecast to dip as far down as the north and northwest Arabian Sea and mop up the moisture to be later transported against the heights of the western Himalayas as well as into the plains of northwest India.

Consensus prediction by international models continues to suggest the westward movement of the Bay ‘low’ to the southwest but at least one model sees slight deepening of the central pressure and consequent strengthening of the system in the process. This phase would become prominent on Friday and Saturday as the ‘low’ encounters the reasonably warm waters of 28 to 29 deg C (above the threshold 27.5 deg C) over the central and adjoining southwest Bay of Bengal.

COOLER WATERS

From here, however, it would aim towards northernmost Sri Lanka and the Palk Straits where sea surface temperatures have cooled down to 26-27 deg C in the wake of the passing of cyclone Nisha, causing the former to let off steam and decelerate.

One model ventures to suggest the breaking up of the system into two on impacting north Sri Lanka, with the more potent system crossing into the island nation. The remainder is shown to stroll towards and wash over along the adjoining Tamil Nadu coast to trigger rains there.

Meanwhile, Global Forecast System (GFS) model runs by the US National Centres for Environmental Prediction are of the view that there is a lull in the seasonal easterlies to northeasterly flows across the Bay which would hold until Sunday.

RAINS PETER OUT

An update by the Regional Met Centre, Chennai, said the 24 hours ending Wednesday morning saw rains weaken in tandem with the prevailing easterlies.

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