Mumbai spared potential repeat of 2005 floods

Vinson Kurian Thiruvananthapuram | Updated on July 05, 2020 Published on July 05, 2020

A less-than-active Bay of Bengal more than helped

Emerging evidence suggests that a mid-tropospheric cyclonic circulation (MTC) was operating behind the enhanced rainfall event over Mumbai, South Gujarat and Saurashtra during the past couple of days, offering a throwback to the evolution of the historic rainfall and flood events way back in 2005.

India Meteorological Department (IMD) had located the MTC off the Gujarat coast, among the most prominent areas identified across the world as capable of hosting and sustaining such a weather system, and has been tracking it after it triggered a spike in rainfall amounts over the adjoining region.

Strong convergence zone

Research has shown that active monsoon conditions over North Konkan (including Mumbai) are usually associated with a trough off the West Coast, low/depression over the North Bay, presence of an MTC of off the North Maharashtra-South Gujarat coast, and a strong pressure gradient along the coast.

The prominent missing link this year was the less-than-active conditions in the Bay, according to experts. As such, the Gujarat-Kutch zone of convergence is among the major 17 zones embedded in the oriental (South-West Asian monsoon) and susceptible to flare-ups from MTCs periodically.

On Sunday morning, the IMD instead zeroed in a low-pressure area lies over Coastal Saurashtra, marked by dense clouding over Saurashtra, Kutch and South Gujarat. The low continues to attract rain-bearing monsoon westerlies to south-westerlies into the West Coast.

Cyclonic circulation in Bay

A cyclonic circulation lies over the West-Central and adjoining North-West Bay off North Coastal Andhra Pradesh and South Odisha, which is capable of pumping in the south-easterly monsoon winds from the Bay into the land-based monsoon trough that connects East India with North-West India.

The IMD has said that the low over Coastal Saurashtra and the intense monsoon flows will feed into each other, allowing the low to become more marked (intensified) by Monday. It stands to gain also from the presence, though truncated, of an offshore trough from South Gujarat to Karnataka.

The land-based trough runs in from Anupgarh (Sriganganagar, Rajasthan) and is aligned along an ideal track that links with Sikar, Gwalior, Sidhi, Ranchi, Jamshedpur, and Haldia before dipping into the East-Central Bay. All these areas over North-West and East India benefit from the proximity to the trough.

Heavy rain, thundershowers

The IMD has forecast fairly widespread to widespread rainfall with isolated heavy to very heavy falls over Gujarat during next 3-4 days and over Konkan and Goa till Monday. Isolated extremely heavy falls are forecast over East Gujarat on Sunday and Monday and Saurashtra and Kutch during the next three days.

To the East, fairly widespread to widespread rainfall or thundershower activity along with isolated heavy to very heavy falls is predicted over East and adjoining parts of Central India during the next 3-4 days.

The monsoon trough across North India too is forecast to become more marked from Monday.

This would likely set up the ground for high convergence of strong moist westerly/south-westerly winds from the Arabian Sea over plains the plains of North-West India. This would bring fairly widespread to widespread rainfall with isolated heavy falls over parts of the region during the next 3-4 days.

Intense thunderstorms and lightning may develop on Sunday across Himachal Pradesh, Uttarakhand, East Rajasthan, Haryana, Chandigarh, Delhi, Uttar Pradesh, Jharkhand, the plains of West Bengal, Chhattisgarh, Odisha, Madhya Pradesh, Telangana, Coastal Andhra Pradesh, Rayalaseema, Gujarat, Assam, Meghalaya, and Kerala.

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Published on July 05, 2020
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