The Hindu Business Line : Persisting `low' over Bay key to monsoon revival

THE trough of low pressure persisting at sea level over the southwest Bay of Bengal over the past few days holds the key to the revival of the northeast monsoon.

There has not been any significant rain activity in much of the peninsula for weeks together. The `low' is now expected to pull itself together and get into `action mode' bringing the reverse monsoon back into the reckoning in parts of the southern peninsula by mid-week next week.

Model projections by the National Centre for Medium Range Weather Forecasting (NCMRWF) indicate the advancement of the rain-belt associated with the Bay system into the Sri Lankan and southern Tamil Nadu coasts by Monday next.

A counterpart weather system seen taking shape around that time over the southeast Arabian Sea off Kanyakumari is expected to bring parts of the southwest coast too under some rain activity.

If these were to proceed to their logical conclusion they would have only perpetuated a trend when mid-December turned `wet' for the peninsula towards the latter part of the northeast monsoon. There have been years when parts of the peninsula, especially Tamil Nadu, have been subjected to heavy rain around this time.

Asked whether the typhoons that battered South-East Asian countries during the past week may have affected the northeast monsoon — just as they did in the case of the southwest monsoon, Dr M. Rajeevan, Director - Forecasting, India Meteorological Department, replied in the negative.

An unusually large number of typhoons forming in the Western Pacific and moving northwards are known to `suck' most of the prevalent southwest monsoon currents to the western Pacific robbing the Indian monsoon circulation of much of its steam. "There may not be a one to one correspondence here. But there is a statistical relationship between North West Pacific typhoons and the Indian summer monsoon," he said.

In the case of the northeast monsoon, though, the typhoons should not create much of a problem not just because the cyclone season in the Bay of Bengal will have ended by that time but also because the flows are originating from the east.

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