The Hindu Business Line : Pacific typhoon pestering monsoon system

Thiruvananthapuram, July 18 A west Pacific typhoon named Kalmaegi raging over the past two days has been the latest drag on the Indian monsoon which finds a surge from the southwest coast faltering.

The typhoon has prevented a nascent trough in the Arabian Sea from deepening to expected levels. Kalmaegi may have weakened as a tropical storm over China but is forecast to re-curve to the northeast and dip into the East China Sea.

Another round of strengthening in the East China Sea is not entirely ruled out, which should be cause of some concern. A west-northwest moving system heading into South China Sea could at least be expected to send in a pulse into the neighbouring Bay of Bengal.

Failure of the peninsular seas to spin up a system strong enough to rally incoming flows around itself has cost the monsoon dear. July normally sees three to four such systems driving rainfall into the mainland. The flows have instead come to be appropriated by stronger systems beyond India’s territorial waters.

Invading dry northwesterlies from West Asia have been another unwelcome feature. They freely mixed with the southwesterlies, unsettling the moisture balance and compromising their carry and precipitation capacity.

Meanwhile on Friday, a land-based cyclonic circulation sprung up over Bangladesh and adjoining Gangetic West Bengal. This is expected to move west over the Orissa coast, according to some model predictions. It will drive rain initially into east and central India.

An India Meteorological Department (IMD) update on Friday said that fairly widespread rainfall activity with isolated heavy to very heavy falls is likely over the Northeast, West Bengal, Sikkim, Bihar, north Uttar Pradesh and Uttarakhand during the next four days.

REVVING UP

The land-based monsoon trough continued to pass through the foothills of the Himalayas. This will act with the incoming cyclonic circulation and rev up the rainfall in the east and northeast.

In the south, the offshore trough from the Karnataka coast to Kerala coast persisted. It is likely to cause fairly widespread rainfall with isolated heavy falls over coastal Karnataka, Kerala and Lakshadweep over the next four days. A warning valid for the next two days said isolated heavy to very heavy rainfall is likely over the North-East, sub-Himalayan West Bengal, Sikkim, north Uttar Pradesh and Uttarakhand. Isolated heavy rainfall is likely over Bihar, coastal Karnataka, Kerala and Lakshadweep as well.

Out look for the next three days said that fairly widespread rainfall activity is likely over the North-East, the Gangetic plains, coastal Karnataka, Kerala and Lakshadweep.

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