The Hindu Business Line : Cyclone alert off as ‘low’ becomes marked

Thiruvananthapuram, May 15 The US Navy’s Joint Typhoon Warning Centre (JTWC) has invalidated Wednesday’s cyclone formation alert issued for the Bay of Bengal basin, even as the causative ‘low’ became well marked on Thursday.

The system lay over east-central and adjoining northeast Bay of Bengal and coastal areas of Myanmar, an India Meteorological Department (IMD) update said. Widespread rainfall with isolated heavy to very heavy fall is likely to pound an already soaked the Andaman Islands during the next two days.

A medium-range forecast from the Ministry of Earth Sciences said that the well-marked ‘low’ will intensify further and move in northwesterly direction.

DISTORTED FEATURE

Meanwhile, back-to-back western disturbances have continued to wreak havoc with the nascent ‘heat low’ over northwest India. A poorly developed ‘heat low’ distorts the pressure gradient along which the monsoon normally gets driven from the ‘high’ over the peninsular south.

The westerlies and their offspring thundershowers, dust storms and squalls have brought down the mercury to below the normal for the season at many places. For days together, bulk of the heating has taken place towards the southeast coast, with even a ‘mirror heat low’ over coastal Andhra Pradesh.

The IMD cited numerical weather prediction models to suggest scattered rain/thundershowers and isolated thunder squalls over the Indo-Gangetic plains for five days from Friday. Scattered rain or thundershowers are likely over West Bengal, Sikkim, the Northeastern States, Orissa and the extreme south peninsula during the next three days.

Isolated rain or thundershowers are likely over the northwest, Chhattisgarh and north Madhya Pradesh while isolated dust storm is likely over Rajasthan. Rain or thundershowers are likely at a few places over south Tamil Nadu, Kerala and Lakshadweep and isolated over north Tamil Nadu.

DAY’S MAXIMUM

On Thursday, however, the highest maximum of 44.0 deg C was recorded at Nagpur, the IMD update said. The day temperatures are likely to remain below normal over northwest and central India during the next three days as well.

International model forecasts indicate that the southwest coast and the northeast would witness varying amounts of rainfall from this weekend in the run-up to the onset of the southwest monsoon. The IMD has set a nine-day ‘window’ on either side of May-29 median for the monsoon to establish over Kerala.

The latest outlook from the US National Centres for Environmental Prediction (NCEP) indicates a blow-up of rainfall along the south Kerala coast during the week ending May 22. This will be followed by a full-scale onset of the monsoon during the week starting May 23, with a rain-belt featuring bands with precipitation amounts ranging from eight cm to 20 cm hitting coastal Kerala.

Almost simultaneously, the northeast too would witness the Bay arm of the monsoon push rains into the region after sprinting through Myanmar and Bangladesh.

The Ensemble Forecast System (EFS) of the US Navy’s Fleet Numerical Meteorology and Oceanography Centre (FNMOC) seemed to suggest organised convection (a likely ‘low’) in the Lakshadweep area around the weekend and its intensification in phases.

The resultant rains are forecast to reach south Kerala around May 20 and a limited progression to the northern parts of the State is indicated from May 23.

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