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Saturday, Dec 03, 2005
Climate & Weather
Industry & Economy - Climate & Weather
Invading westerlies lop the top off `Baaz', weaken storm
Thiruvananthapuram , Dec 2
TROPICAL Cyclone Baaz underwent at least three rounds of deterioration over the Bay of Bengal waters to become a well marked `low' by Friday night, ensuring that it would have scaled down to barely tropical storm strength at the time of landfall.
It will still be able to buffet the coast with winds reaching 50-60 km/h before a truncated `Baaz' proceeds to drive up rain bands into the interior parts of Andhra Pradesh and Tamil Nadu, says a forecast by the National Centre for Medium Range Weather Forecasting (NCMRWF).
An eventful past 24 hours began to unfold with the cyclonic storm weakening to a deep depression at 5.30 p.m. on Thursday while being unmoved from its position about 350 km away off Chennai. It then moved northwest to a location 250 km east of Chennai, but had weakened further into a depression by 5.30 a.m. on Friday. By 8 p.m., it had become a well-marked `low.'
According to Dr K.J. Ramesh of the NCMRWF, the strength of the steering anti-cyclonic flow aloft may have proved too much for the system even as it came under the influence of a mid-latitude westerly trough moving to the northeast.
The net result was that the organised upper level clouds of the vertical formation got sheared from the top, dispersing them to a direction northeast of the centre in line where the domineering winds were blowing.
The relatively cooler coastal waters and proximity to land may have undermined the base of the towering system.
On Friday, bands of convective cloud bands were found to have extended to the coasts of north Tamil Nadu and Andhra Pradesh and light to moderate rainfall activity had already been triggered in these areas.
Under this scenario, fairly widespread rainfall with isolated heavy falls are likely over the extreme north coastal Tamil Nadu and coastal Andhra Pradesh during the next two days.
Subsequently, scattered rain is likely in Kerala, Karnataka and the Lakshadweep islands.
The Honolulu-based Joint Typhoon Warning Centre (JTWC) had come out with the prediction that moderate wind shear and proximity to land will cause `Baaz' to undergo considerable weakening on the seawaters itself. On Friday, it said that the speed with which system cantered towards coast did not exceed four knots (7.5 km/h) against the six knots (11 km/h) forecast on Thursday.
The convection got displaced as a result of the increasing wind shear, which ruled out any further intensification of the system. This was the final advisory on `Baaz' but the system will be closely monitored for signs of regeneration, the JTWC added.
Meanwhile, the NCMRWF was closely watching the renewed buzz in the Andaman Sea where some convective clouding has already been observed. It is quite possible that the warming seas in the extreme southeast Bay of Bengal (around 90E) throws up a cyclonic circulation sooner than later.
If properly evolved, this migrant circulation from the South China Sea could set up the next monsoon system in the Bay, third in a row.
The overbearing presence of the mid-latitude westerly trough did a `Baaz' on Friday with the convective cloud bands of the `low' over the east-central Arabian Sea as well.
The lopped off bands extended in north easterly direction over the Konkan coast, madhya Maharashtra, Vidarbha, south Gujarat and Madhya Pradesh on Friday as well. This will bring isolated to scattered rainfall over these areas during the next 36-48 hours.
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