Heavy rainfall has been forecast at isolated places over South Tamil Nadu and Puducherry on Thursday, while thunderstorms would roll out at some other places across these regions as also over neighbouring Kerala, following the arrival of the North-East monsoon on Wednesday.

November 2-4 would see fairly widespread rainfall over Kerala and Karnataka; scattered over Tamil Nadu and Puducherry as well as over North-East India. Isolated rainfall is forecast over Odisha and Lakshadweep Island, India Meteorological Department (IMD) said.

South-West monsoon exits

Earlier on Wednesday, the IMD announced that the North-East monsoon rains had commenced over extreme South Peninsular India after predecessor South-West monsoon had exited the entire country.

A cyclonic circulation lay over South-West Bay of Bengal off the North Tamil Nadu coast holding the easterly to north-easterly flows together. A rush of activity in the upstream South China Sea is engaging the attention of weather watchers for potential impact on the Bay of Bengal waters.

South China Sea typhoon

On Wednesday, a typhoon (cyclone) in the South China Sea had crossed the Vietnam coast and is likely sending out a remnant across Thailand and Myanmar into the Bay. Latest model projections do not, however, show it getting a second lease of life as a low-pressure area in the Bay.

Instead, the remnant circulation is projected as shifting places in the larger Bay and setting up a broad-based trough of low-pressure (as against a full-fledged low-pressure area). But it would still be capable of pushing in moisture-laden easterly to north-easterly flows into the Tamil Nadu coast.

Second typhoon in making

This typhoon would be followed by another, located on Wednesday over the Philippine Sea as a rudimentary circulation. It would earn its spurs as a typhoon and push across Vietnam and Thailand to drop anchor as a weakened circulation in the Bay during the first week of November.

Global models have indicated that the seasonal rainfall over the South Peninsula and the adjoining areas may pick up by November 7 after the Arabian Sea also gets active. The wet and rainy phase may last through the entire month of November and potentially into early December.