Agri Business

Heavy rain belt shifting from foothills to plains of N-W India

Vinson Kurian Thiruvananthapuram | Updated on July 28, 2020 Published on July 28, 2020

The monsoon trough, which lies close to the foothills of the Himalayas and presides over a wet session over East and North-East India, is likely to descend southward from tomorrow (Wednesday) and bring the heavy to very heavy rain to bear down on the plains of North-West India and adjoining Central India.

The trough will allow strong southerly/south-westerly flows from the Arabian Sea and progressively south monsoon flows from the Bay of Bengal to converge over North-West India on Wednesday and Thursday. Till then, the monsoon would stay mostly subdued over North-West and adjoining Central India.

The India Meteorological Department (IMD) has said that the rainfall intensity and distribution could increase over North-West India and Madhya Pradesh from Wednesday to Friday. Since the trough is heading southward, it is likely that a helpful cyclonic circulation may form in the adjoining Bay of Bengal.

Cyclonic circulation in Bay

What inspires confidence in this outlook is the arrival of a monsoon-friendly Madden-Julian Oscillation (MJO) wave off Africa and its concurrent passage to the West across the Arabian Sea and the Bay. The wave is responsible for formation of lows and depressions, apart from precipitating even monsoon onsets.

In fact, the IMD has located a circulation lies over South-East and adjoining South-West Bay but that is expected to move closer to the Sri Lanka-Tamil Nadu-Andhra Pradesh coast, and head North-West into Peninsular India. It could weaken under the influence of another low brewing over the North-East Bay.

It is this circulation that is forecast to strengthen and sustain long enough to cross the West Bengal and Odisha coast and set off for West or North-West India, the first full-fledged low from the Bay to do that during this season. It would ensure spatial and temporal spread of rainfall along the way and across.

Heavy to very heavy rain

The IMD has forecast widespread rainfall with isolated heavy to very heavy falls over Uttarakhand, Uttar Pradesh, Bihar, hills of West Bengal, Sikkim and the North-Eastern States (mainly Arunachal Pradesh, Assam and Meghalaya) until Thursday; and over Punjab, Haryana, Chandigarh, Delhi, Himachal Pradesh and Madhya Pradesh from Wednesday to Friday.

Isolated extremely heavy falls are forecast over the hills of West Bengal ad Sikkim until Thursday even as it rained over Uttarakhand and Bihar on Tuesday. Meanwhile in the South, fairly widespread to widespread rainfall with isolated heavy to very heavy falls are forecast over Karnataka, Tamil Nadu and Kerala during next 4-5 days as the monsoon strengthens over both the Arabian Sea and the Bay.

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Published on July 28, 2020
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