The Hindu Business Line : Bay `low' set to intensify soon

The long-delayed but crucially important low pressure area over Bay of Bengal materialised on Friday, with all models suggesting its rapid intensification into a monsoon depression.

A forecast by the National Centre for Medium Range Weather Forecasting (NCMRWF) said the system is likely to intensify over the next 48 hours and move typically west-northwest into Orissa, Chhattisgarh and Madhya Pradesh. This will bring widespread rainfall with isolated heavy showers over Gangetic West Bengal, Jharkhand, Orissa and Coastal Andhra Pradesh during next two to three days. The activity will extend into Chhattisgarh, East Madhya Pradesh, Vidarbha, East Uttar Pradesh and Telangana subsequently.

HEAVY FALLS SEEN

With the system moving inland after three days, the wet session over Konkan, Goa, Madhya Maharashtra and South Gujarat will bear down with renewed vigour. Heavy to very heavy falls have been indicated at a few places in this region and isolated extremely heavy rainfall in some others.

Dr Akhilesh Gupta of the Department of Science and Technology told Business Line that the system had good potential for intensification. But indications are that the system will head mostly west to set up an interaction with the resident cyclonic circulation over Gujarat.

Dr Gupta did not rule out the possibility of a cyclonic circulation forming over Gujarat as a result, which can let loose a torrent and hold it for a much longer time than any other monsoon system. It can co-exist with a monsoon depression to spearhead a busy wet session till such time that the two stay apart at a minimum distance of 500 km.

SECOND LOW SOON?

Further intensification of the Bay system is ruled out for two reasons: one, vertical wind shear is very high, and two, the location is too close to land, which reduces the stay over warm waters of the Bay. Significantly, Dr Gupta cited from the European Centre for Medium-Range Weather Forecasting (ECMWF) model suggesting the formation of a second `low' over the Bay by July 8.

Dr Paul Roundy of the University of Colorado discounted the probability of a tropical cyclone developing in the Bay of Bengal any time soon.

But he saw a broad monsoon depression currently extending into the region.

Tropical cyclones are rare in the Bay of Bengal during July, presumably because the monsoon trough tends to lie largely over land.

The forecast scheme has done very well in the past in the Bay, he said. But Dr Julian Heming of the UK Met Office said his model featured only a `weak low' over Bay of Bengal.

Commenting on the scenario over the Central Pacific, Dr Roundy said the developing system is most likely to begin recurving as it crosses the Philippine islands. This could result in its re-intensification but it will be prone to move in a north-northeast direction and remain neutral to Indian monsoon.

Dr Heming agreed that there is a consensus on the system developing of east of the Philippines.

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