Winds blowing into Bay gathering pace

Westerly to southwesterly winds blowing into the Bay of Bengal may start gathering momentum over the next few days, an India Meteorological Department (IMD) update said on Friday evening.

This is considered a good augury for the onset of southwest monsoon over Andaman and Nicobar Islands, the country's farthest outpost towards east-southeast, around the normal timeline of May 15-20.

In fact, satellite pictures and global models showed that these winds have already picked up pace over upstream equatorial Indian Ocean just south of Sri Lanka and are racing into the Bay, pulled in by a weak low-pressure area in the southwest Bay.

Clouds have filled the region, and they would continue to be guided towards the Myanmar region as the weak ‘low' heads in a north-northeast direction.

From Myanmar and adjoining western parts of Southeast Asia, some of the floating moisture is seen being diverted northeast India, which may spark further activity in the already turbulent weather over that region.

IMD has also observed that the wind direction and strength indicates that the pressure-gradient - arising from enhanced warming in the Bay - may be building ahead of the onset of the monsoon.

The ideal pressure gradient was conspicuous by its absence through the course of the previous monsoon.

This had kept the Bay unusually quiet and left behind large rainfall deficiencies over east and northeast India.

In contrast, the Bay has warmed up to around 30 deg-Celsius already this year – well above the threshold for it to sustain low-pressure areas, tropical depressions or even a cyclone.

But nothing of that sort has happened so far this year since a barrage of strong opposing flows from prevailing western disturbances have prevented any system from taking shape. The latest in the series of these westerly systems was on show on Friday over north Pakistan and adjoining Jammu and Kashmir with an induced cyclonic formulation clinging to its underbelly.

The IMD has warned of isolated thunder squalls over Himachal Pradesh, Uttarkhand, Punjab, Haryana, Delhi, north Rajasthan, Uttar Pradesh, Jharkhand, Orissa and Gangetic West Bengal until the day after (Sunday).

The induced upper air cyclonic circulation was parked over northwest Rajasthan on Friday.

A trough ran out towards east-southeast from here across Haryana, Uttar Pradesh, southwest Bihar and Jharkhand to end up in a counterpart circulation over Gangetic West Bengal.

Satellite imagery on Friday afternoon showed convective clouds over parts of south and adjoining central Bay of Bengal and Andaman Sea.

An extended outlook valid until Wednesday spoke about the possibility of a fresh western disturbance approaching northwest India.

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