The Hindu Business Line : ‘Low’ becomes well marked over Bay

Thiruvananthapuram, Nov 13 The anticipated low-pressure area surfaced over southeast Bay of Bengal on Wednesday night itself, and has since intensified to being well-marked on Thursday as the system as a whole moved laterally to the southwest Bay.

India Meteorological Department (IMD) expected the well-marked ‘low’ to fast-forward as a depression in the next 24 hours but the US Joint Typhoon Warning Centre (JTWC) has set up a tropical cyclone watch in the Bay.

On Thursday, the JTWC traced the system approximately 430 nautical miles (796 km) east of Chennai. Recent satellite imagery showed deep convection developing near the centre of the slowly consolidating low-level circulation centre (LLCC).

This disturbance continues to enjoy the twin advantages of low to moderate vertical wind shear and favourable diffluence aloft, the window effect that helps the system to breathe and grow in strength. Maximum sustained surface winds were estimated at 20-25 knots (37-46 km/hr).

‘FAIR’ POTENTIAL

Due to the consolidating deep convection, potential for the development of a tropical cyclone (a ‘depression’ or above) in the next 24 hours is upgraded to fair, the JTWC said.

Numerical weather prediction models indicate an initial west-northwestward movement for the system, bringing increased rain activity over the south peninsula.

A warning issued separately by the IMD said that isolated heavy rainfall is likely over Andaman and Nicobar Islands, south Tamil Nadu and Puducherry during the next 36 hours.

Three days from Sunday would witness fairly widespread rainfall activity with isolated heavy falls over coastal areas of Tamil Nadu, south Andhra Pradesh and Lakshadweep. The rains are expected to accelerate over the remaining parts of the south peninsula as well.

The Chennai Met Centre said in its update that rainfall occurred at few places over Kerala during the 24 hours ending on Thursday morning. Isolated rainfall occurred over Tamil Nadu, but the southern districts of Tamil Nadu came in for some wet weather from a suitably guided band of northeasterlies.

Forecast for the next two days said that rain or thundershowers are likely to occur at many places over south coastal Andhra Pradesh, coastal Tamil Nadu and Puducherry and at a few places over Rayalaseema and north coastal Andhra Pradesh.

THUNDERSHOWERS FORECAST

Isolated rain or thundershowers are likely over interior Tamil Nadu and south Kerala.

As for the north, the IMD cited current meteorological analysis and numerical weather prediction models to suggest that a western disturbance is likely to cause scattered precipitation activity over the western Himalayan region during the next three days.

Minimum temperatures are above normal by 5-6° deg C over parts of Rajasthan, Haryana, Punjab, some parts of central India and northwest Jammu & Kashmir; 3-4° deg C above normal over remaining parts of central and northwest India and Gujarat; and 2-3° C above normal over remaining parts of central India and adjoining areas.

The mercury is expected to fall as the region comes under the grip of cold and sinking air in the rear of the western disturbance.

This is expected to happen after Sunday, the IMD said.

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