Wednesday, May 04, 2011

Heating trend may once again get briefly disrupted

Expectations of low-pressure area in the Bay of Bengal having subsided, the focus has once again shifted to the heating pattern in northwest India.
The heating in this geography has a crucial bearing on the strength and prospects of the impending southwest monsoon.

The highest maximum recorded in the country on Monday was reported from this region, but at 44.4 deg Celsius, it might just have failed to warm the cockles of hardened monsoon watchers.
The heating has admittedly been below par during the season until now and arrival by Thursday of a fresh but heat-killer western disturbance as forecast by India Meteorological Department (IMD) may pour cold water on any hopes of a smart pick-up in mercury over this region.

Sustained heating is required to set up the “heat low,” a peculiar atmospheric phenomenon special to this part of the world, that helps moisture-laden southwesterly monsoon winds march up north along the pressure gradient.

The IMD maintained its outlook for the westerly system on Tuesday morning, which would affect the western Himalayan region and adjoining plains of northwest India from Thursday.
As a result, scattered rain or thundershowers are expected to break out over the western Himalayan region, as per a short-term outlook valid until Friday.

Isolated dust storm or thunderstorm would occur over adjoining plains of northwest India during this period.
The IMD has said that no significant change is expected in maximum temperatures over northwest, west and central India. But even dust storms/thunderstorms can cap maximum temperatures by varying margins, even if temporarily.

Meanwhile, an upper air cyclonic circulation persisted over east Uttar Pradesh.
A trough from this system extended downward, but unlike until the previous day, was cut short over north coastal Andhra Pradesh. It ran through east Madhya Pradesh, Chhattisgarh and interior Orissa.
The other upper air cyclonic circulation, which was expected to father the “low” in the Bay, hung above central parts of south Bay of Bengal.
Satellite imagery early on Tuesday evening showed the presence of convective clouds over parts of east-central and south Bay of Bengal and southeast Arabian Sea.
A short-term outlook valid until Friday said that widespread rain or thundershowers would occur over Andaman and Nicobar Islands, scattered over south Karnataka, Kerala and Lakshadweep and isolated over rest of peninsular India.
Fairly widespread rain or thundershowers would occur over the Northeastern States.
Scattered rain or thundershowers would occur over sub-Himalayan West Bengal, Sikkim and isolated over the rest of east India.
An extended forecast valid until Sunday said that fairly widespread precipitation activity would unfold over western Himalayan region.
Isolated dust storm or thunderstorm could break out over the adjoining plains of northwest India.
Isolated rain or thundershowers would occur over the Northeastern States and adjoining east India. 

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