Thursday, December 17, 2009

Remnant ‘low' continues to rain over coastal TN

Tuesday's well-marked ‘low' over north Sri Lanka and adjoining Gulf of Mannar has further weakened into a ‘low' and has persisted around the same region overnight on Wednesday.

A remnant of erstwhile tropical cyclone Ward that has mostly failed forecasts made by the best centres around the globe, the system threw up signals that it might retrace the very track it had trodden while making the first landfall over Sri Lanka.

Wet spell

This would take it careening north along the Tamil Nadu coast to sustain the wet spell up till Chennai before sliding into open Bay of Bengal, said a US National Centres for Environmental Prediction (NCEP) forecast.

This spell could last until December 23, the NCEP precipitation model said on Wednesday.

It is also likely that the moisture-laden easterlies get acted upon by westerlies blowing into the peninsula.

This could cause the easterlies to drop some moisture over parts of internal peninsula as also the southern fringes of central India, the US forecaster said.

Going forward, it said that widespread light to moderate rains are likely to hang over parts of the peninsula, including the northern belt, during December 24 to January 1, as seasonal easterlies start to blow into the peninsula afresh.

Once again, the core area of weather panning out would be southeast Tamil Nadu-north Sri Lanka coasts from where the rains would get propagated north and west, according to the NCEP.

The prospect of fresh rains is being attributed to the arrival of a weather-boosting Madden-Julian Oscillation (MJO) wave in the upper levels over the equatorial Indian Ocean and adjoining southern Indian peninsula.

Successful season

The wave would be active from December 22 to 29, according to the Jones MJO model tracker as also Coupled Linear Inverse model of the Earth System Research Laboratory of the US National Oceanic and Atmospheric Administration.

This would effectively mean that what has till now been a successful northeast monsoon (11 per cent surplus all-India as on December 9) would last until the very end (normally December 30).

But the Empirical Wave Propagation technique of the NCEP for tracking MJO movement is of the view that the benign phase (not very intense, though) might last until the last week of January, 2010. But this would bear watching.

An update from the Chennai Met Centre said on Wednesday that the northeast monsoon has been vigorous over Tamil Nadu.

Rainfall occurred at many places over Tamil Nadu and at a few places over Rayalaseema.

Isolated rainfall occurred over coastal Andhra Pradesh, Kerala and south interior Karnataka.


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


A warning valid for the period said that isolated heavy to very heavy rain is likely to occur over coastal Tamil Nadu and Puducherry.

Towards the north, maximum temperatures were above normal C over many parts of central and adjoining east India, north Andhra Pradesh and some parts of west western Himalayan India.

Minimum temperatures were appreciably above normal over parts of Rajasthan, Gujarat, Madhya Pradesh and interior peninsular India.

Forecast by India Meteorological Department said that isolated rainfall activity is likely over Northeastern States.

Isolated rain or snow over western Himalayan region has been forecast during the next 24 hours. Isolated light rain or thundershowers are likely over central India.

Minimum temperatures are likely to fall over northwest India during the next two days with the passage of a prevailing western disturbance.

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