Heavy to very rainfall has been forecast for Friday and Saturday over Coastal and South Interior Karnataka and Kerala as a potent combination of a cyclonic circulation off the Karnataka coast and a truncated offshore trough from South Maharashtra coast to North Kerala, watched from above by a zone of monsoon turbulence, continue to dictate terms to regional weather.

Each feeds into the other, and the circulating moisture-laden winds from the Arabian Sea blast into the heights of the Western Ghats to be propelled higher to cool, condense and precipitate.

Fairly widespread to widespread rainfall with isolated heavy falls, thunderstorm and lightning are forecast over Peninsular India for another 4-5 days. The next low-pressure area is expected to come up over the Bay of Bengal by Sunday.

International model forecasts continue to suggest that the Arabian Sea and the Bay of Bengal have enough fuel left to power the monsoon at least until September 23, subsequent to which the intense rainfall belt may move northwards to Coastal Karnataka-Goa on the West Coast and Andhra Pradesh-Odisha on the East Coast.

The IMD has forecast heavy to very heavy rainfall over Coastal and South Interior Karnataka and Kerala; heavy over Madhya Maharashtra, Konkan, Goa, Coastal Andhra Pradesh, Telangana, Rayalaseema, North Interior Karnataka, Tamil Nadu and Puducherry.