Monsoon low-pressure areas and cyclonic circulations marching out of the Bay of Bengal as if on the assembly line and crossing the Odisha coast do not augur well for the soaked hinterland over Central India and the West Coast. The genesis and track of these systems are always fraught with the threat of sustained heavy rain for days, as is borne out from the experience of the last few days. Being one of the two ‘sweet spots’ for monsoon circulations to converge, Odisha ensures rain for Central India and the West Coast in the main. The other spot is the Head Bay of Bengal, from where these systems direct rain clouds to the plains of North-West India.

Flows from either side

Systems crossing the Odisha coast cause the eastern end of the monsoon-driving trough over land pinned down to East and Central India while drawing in moisture-saturated flows from the Arabian Sea on the other side. The sustained feed of moisture from either side (from the Arabian Sea and the Bay) in this manner will maintain the potency of the systems as they travel West over Central India towards Mumbai and Gujarat, dumping heavy to very heavy rainfall along the way.

‘Low’ leaves flooding trail

For instance, the first low-pressure area of the season emanating from the Bay and crossing Central and West India has left a flooding trail, and doesn’t seem to have lost any of its potency after crossing Gujarat and entering South Pakistan. A successor cyclonic circulation (it doesn’t need even a ‘low’ in these surcharged environments to pour it down) from the Bay has parked itself over North Odisha and adjoining Chhattisgarh (and lately over Vidarbha), as an India Meteorological Department (IMD) update said this (Thursday) morning.

Successor may hit same track

It is also expected to meander across Central India, and even before it can enter West Madhya Pradesh and Gujarat, it would likely see a third circulation in the current series pop up over the Bay by Saturday. This time around, it might land to the South of Odisha and North Andhra Pradesh coasts initially, only to move later towards North-East to access the sweet spot over the Odisha coast. Numerical projections from the IMD suggest that this system will drop anchor there for a few days and gain in strength before hitting the familiar track, triggering another wave of heavy to very heavy rainfall over Central India. It may re-intensify over Gujarat as it readies to exit land and steps into the Arabian Sea.

Gujarat, Mumbai on guard

The state of Gujarat, the Mumbai metropolis and West Madhya Pradesh need to keep strict vigil during the tenure of these systems. Similarly, the West Coast will encounter flooding rain as the offshore trough has come back to life again, and on Thursday morning, it extended nearly full-strength from Gujarat to the Karnataka coast. The lingering impact of a Madden-Julian Oscillation (MJO) wave has kept the Bay of Bengal boiling even after its core moved away into the West Pacific. The Bay may stay active until July 26, per global model projections.

Heavy clouds converge

This (Thursday) morning, heavy clouds hovered over a stretch from Okha, Dwarka, Bhatiya and Porbandar and an area bounded by Bhanvad, Kalavad, Gondal, Jetpur, Upleta and Kuttiyana; Veraval, Kodinar, Una, Rajula, Mahua, Talaja, Navasari, Billimora, Valsad and Vapi along Coastal and South Gujarat; and Palghar, Vasai-Virar, Wada, Shahapur, Thane, Ambarnath and Mumbai in Maharashtra. Elsewhere, they hung heavy over the East Coast from Amalapuram, Tuni, Visakhapatnam, Vizianagaram, Tekkali, Sompeta, and Brahmapur along Andhra Pradesh and Odisha, as well as the adjoining interior.

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