Feeble cyclonic circulation over TN bl-premium-article-image

Vinson Kurien Updated - December 02, 2011 at 10:32 PM.

weather

Southwest Bay of Bengal has shown some signs of life with a trough of lower pressure (not amounting to a low-pressure area) getting thrown up by the prevailing easterly flows.

A feeble upper air cyclonic circulation too has spun up over south Tamil Nadu and neighbourhood in the lower levels.

NO MJO SUPPORT

The trough extended to west-central Bay of Bengal reflective of the pattern of build-up ahead of the meaningful wet session last week culminating in a low-pressure area and a near-cyclone.

But things do not look that promising given that there is no support from the upper levels of the atmosphere when a transiting wet phase of a periodical Madden-Julian Oscillation (MJO) wave set up the ground for cloudiness and rain.

The periodical MJO wave that alternates in wet and dry phases is in the process of travelling further to the east over Indian Ocean. Its influence is confined to equatorial East Indian Ocean and adjoining south Bay of Bengal. Model forecasts suggested the possibility of a weather system forming southeast Bay but getting propelled to the east-northeast.

In the circumstances, rains are being forecast for parts of coastal Tamil Nadu and the extreme south peninsula.

An India Meteorological Department (IMD) forecast valid until Monday sad that rain or thundershowers are likely at many places over Andaman and Nicobar Islands and at one or two places over extreme south peninsular India.

Meanwhile, to the northwest, a feeble western disturbance has drifted in over north Pakistan and was waiting to move further to the east across the border to northwest India.

Rain or snowfall has been forecast at one or two places over Jammu and Kashmir.

Isolated rain or thundershowers is likely over the Northeastern States from Saturday.

NO DENSE FOG

Fog or shallow was observed over parts of Indo-Gangetic during the 24 hours ending Friday morning.

Stations where visibility reduced to 200m and below were Amritsar, Karnal, Palam (Delhi) and between 500m 200m at Ridge (Delhi), Aligarh, Agra, Bharatpur, Lucknow, Fursatganj, Varanasi, Tehri and Patna.

An IMD outlook ruled out dense fog conditions over the Indo-Gangetic plains during the next three days.

Published on December 2, 2011 16:04