The Hindu Business Line : Easterly wave may stall, get split

It appears that a chunk of the incoming easterly wave would get deflected in a north-northeast direction and culminate in a rousing wet session over West Bengal, Bangladesh and even adjoining Myanmar.

Residual moisture would get spilled into the southern peninsula, especially along the southeast coast, according to near consensual forecasts by international weather models. The Ensemble Forecast System of the US Navy’s Fleet Numerical Meteorology and Oceanography Centre says that piloting rains should reach the peninsular coast Thursday onwards, before intensifying.

The parent trough located in the southwest Bay of Bengal on Wednesday could get split into two, with the offspring travelling to the north-northeast under the coercive influence of opposing westerlies. The Bay waters to the north and northeast are relatively cool, and would decelerate the system.

The weakened system would crawl into the Bangladesh coast, only to be greeted by a resident pool of moisture in the region. On Wednesday, a helpful trough from sub-Himalayan West Bengal and Sikkim lay extended to the North Bay of Bengal through Gangetic West Bengal.

This would provide the needed fuel for the system to rain it down there, before being pushed into the south-southeast over parts of Indo-China as well.

LEAD TIME

The warmer waters in the southwest Bay of Bengal would give the remnant system sufficient lead time, and coupled with the longer stay mandated by the invading westerlies, it could endow itself with the means to spin up to near-cyclonic speeds.

The strengthening system might just move a little to the east-northeast, but would be made to apply brakes as it encounters the cool waters in that part of the Bay.

The opposing trough embedded in westerlies is seen as digging up some weather over northwest India around March 30 and into the first week of April. The concurrent wet session in the southern peninsula may fluctuate on day-to-day basis, especially over Kerala and Tamil Nadu.

The cyclonic circulation over Gujarat and adjoining Saurashtra persisted. Another cyclonic circulation lay over east-central Arabian Sea off the Karnataka, Goa and Maharashtra coasts. A trough ran down from Vidarbha to Kerala through Marathwada, Madhya Maharashtra and north interior Karnataka.

An India Meteorological Department forecast on Wednesday said that rainfall activity is likely to remain subdued over south peninsula with possibility of only isolated to scattered rain or thundershowers during the next three days. But the Northeastern States are likely to witness scattered to fairly widespread rain or thundershowers accompanied by isolated thunder squalls.