The Hindu Business Line : Monsoon withdrawal to start from Monday

Conditions for withdrawal of monsoon are expected to start building up over extreme west Rajasthan from September 11 onwards, 10 days behind schedule.

September 1 is the normal date for withdrawal to start, but successive monsoon low's racing in late from the southeast of the country had left a draping of moisture hanging over the region.

The seasonal anti-cyclone that presides over the withdrawal phase cannot settle into place unless the moisture rains out completely from the region.

LAST SYSTEM

The well marked `low' over southwest Rajasthan and neighbourhood weakened overnight on Friday and moved away westwards. This could be the last monsoon system to curl into the region given that the brewing `low' in the Bay of Bengal would not be able to progress much inland due to stressed moisture supply.

The National Centre for Medium Range Weather Forecasting (NCMRWF) kept up the vigil for the `low', expected to form out of a cyclonic circulation over the Bay any time after Monday. But Dr Akhilesh Gupta of the Department of Science and Technology was sceptical about its longevity.

NOT DIPPING

This is because there is no northwest-to-southeast monsoon trough presently dipping into the Bay, which is normally what receives the `low' and allows it to roll over into land.

The system slowly meanders its way into west-northwest across central and northwest India producing rain.

In any case, the east-west oriented shear zone of monsoon turbulence is active in the extreme south peninsula. A cyclonic circulation is already embedded into the shear zone and located over land across Tamil Nadu, south interior Karnataka and Kerala. This is likely to sustain for another 48 hours, bringing fairly widespread rainfall with isolated heavy falls over the south peninsula.

RAINS IN EAST, SOUTH

As is to be expected during the weakening phase of the monsoon, rains have extended to the eastern region of the country, including the southeastern seaboard and the northeast.

An NCMRWF forecast said isolated heavy falls are likely over Tamil Nadu, Pondicherry, Kerala, Lakshadweep, Sub-Himalayan West Bengal, Sikkim and the North-East during the next three days.

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