The Hindu Business Line : Heat wave relents under easterly influence

Thiruvananthapuram June 11 Some respite from sizzling hot conditions is at hand for north and northwest India under the benign influence of an unsettled weather pattern concurrently causing torrential rainfall over eastern China.

The confluence of the prevailing southwest monsoon current and an extra-tropical westerly trough far to the east is impacting the hills of north India in the form of an `easterly pulse' with an embedded circulation.

It is sending out some peripheral rain bands to parts of the hilly regions while setting up dust storms in the plains, said Dr K. J. Ramesh of the Department of Science and Technology. This has prevented maximum day temperatures from building further on an already high base of 45 deg C in most parts of the region.

But hot westerlies from the northwest could be expected to roar back into the plains once this circulation dies out. Going forward, however, anticipated moisture feed from what looks like a strengthening monsoon current should bring in isolated thundershowers to Delhi and other places in the region, Dr Ramesh said.

The apprehension is that the incursion of moisture into the area in this manner could go to make life unbearable what with daytime temperatures expected to remain on the wrong side of 40 deg C. The scheduled time of arrival of monsoon into the region is only by June-end.

Progress report

Meanwhile, the monsoon continued to make noticeable progress in the east and northeast while conditions are becoming favourable for its onward progress on the west coast, an update by India Meteorological Department (IMD) said on Monday.

The belt of heavy rain expected to sit over the Orissa region is fast evolving. This will be part of a larger low-pressure area that is seen materialising close to land over the Orissa-West Bengal coast.

Development of a full-blown `heat low' in northwest India and adjoining Pakistan is the latest emerging positive signal for monsoon to progress to the north on its own. It would not need to wait for an Arabian Sea `low' to hitch a ride.

`Heat low' is a vitally important component in the monsoon system and sets up the ideal pressure gradient that helps the monsoon current to glide to the north. It gets established over the desert region (Rajasthan and further into the west) where there are few clouds.

The main heat low is across the international border into Pakistan.

Viewed from the planetary angle, though, the `Indian monsoon low' extends from the northern hemisphere Africa to southern Asia.

Rainfall activity

The IMD update said that conditions are favourable for further advancement of the monsoon into some more parts of Konkan, Goa, south Madhya Maharashtra and some more parts of the interior peninsula during the next three days.

Fairly widespread rainfall activity with isolated heavy to very heavy falls is likely over the north-eastern States and adjoining east India.

Isolated heavy to very heavy rainfall is likely over the north-eastern States, West Bengal, Sikkim, coastal Karnataka, Kerala and Lakshadweep during the next two days.

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