An eagerly awaited low-pressure area in the Bay of Bengal has changed the complexion of the monsoon, triggering heavy to very heavy showers over the West Coast and Central India and preparing to unleash its fury over North-West India.

The ‘low’ briefly ratcheted up in strength, but weakened on Monday. It has not compromised the monsoon in any manner; the remnant circulation is potent enough to steer it, given the ‘surcharged’ weather conditions.

What has set up these is the abundant feed of moisture both from the Bay of Bengal in the East and the Arabian Sea from the West and directed into the ‘low’ located over Odisha on Monday.

The monsoon flows over the Arabian Sea combining with an incoming western disturbance have thrown up a counterpart circulation over South Pakistan that has since checked into Gujarat.

In fact, an existing circulation was located just to the east over Gujarat.

Besides, the offshore trough, another feature associated with an active monsoon, also lies extended from South Gujarat to Kerala coast.

These have rendered the South Gujarat-Mumbai-Konkan belt the fulcrum of enhanced monsoon activity, allowing for the rare but desirable spectacle of opposing wind flows laden with oodles of moisture running into each other.

Interaction of flows The prospect of interaction of these winds over West, North-West India and adjoining Central India would set the stage for an ‘explosive’ phase of the monsoon marked by heavy to very heavy rain and even stormy conditions.

The interaction of westerly and easterly winds triggers a huge churn in the atmosphere in which the rising motion of air cools the moisture instantaneously, triggering heavy precipitation.

Signs to this effect were already visible in terms of overnight rain on Monday morning when Dehradun was drenched with 18 cm, Bhira recorded 15 cm, Harnai and Alibagh 13 each; and Mahabaleshwar 12 cm.

This is only a sample of things to come from a monsoon that is powered by twin engines (in the form of circulations from the Bay and the Arabian Sea) and effectively put on ‘auto pilot.’

Productive phase The India Met Department (IMD) has dropped hints to the effect that the ongoing week would be the most productive phase of the monsoon after it arrived over the Kerala coast almost a month ago.

It said the monsoon would advance rapidly over Gujarat, Madhya Pradesh, Bihar, East Uttar Pradesh, West Uttar Pradesh, Haryana, Chandigarh, Delhi, Punjab, Uttarakhand, Himachal Pradesh and Jammu & Kashmir over the next five days.

It would also enter parts of Rajasthan, the border state in North-West India, and is largely seen covering enough ground to make good its lag over Central India while still managing to keep up with its itinerary.

Meanwhile, a familiar weather tracker of the US Climate Prediction Centre has hinted at the possibility of a follow-up low-pressure area forming over the Bay of Bengal by June-end.

This would effectively push the expansive phase of the monsoon early into July, although there is also the possibility that a customary ‘break phase’ of the monsoon may not be too far behind.

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