Tamil Nadu, Puducherry, Kerala, and South Interior Karnataka are expected to receive heavy rain from Wednesday at isolated places for three days, ahead of the arrival of the North-East monsoon.

The India Met Department (IMD) has maintained the watch for seasonal showers to formally begin over the South Peninsula from Thursday as the helpful easterly wind regime settles over the Bay of Bengal.

‘Low’ fails forecasts

Across international waters, Super typhoon ‘Yutu’ is entering the South China Sea and pumping easterlies into the Bay. The weakened typhoon is, however, forecast to steer itself away to the North, towards South China.

Back home, an anticipated low-pressure area failed to materialise over the North-West Bay of Bengal; an overnight cyclonic circulation is hovering off the Andhra Pradesh-Odisha coast, pushing some rain into the region. This would be a blessing in disguise for easterly flows entering the Bay since they would not be required to feed into the stray ‘low’ for long; instead they would be able to reorient themselves towards the Tamil Nadu coast.

The Chennai Met Centre in fact sees the rains escalating on Thursday in time for the onset of the North-East monsoon, with heavy to very rain being forecast at isolated places over Tamil Nadu and Puducherry.

Heavy rain is forecast the same day for Kerala and South Interior Karnataka. On Friday, Tamil Nadu, Puducherry, Kerala and South Interior Karnataka would receive heavy rain, according to this outlook.

To grow in intensity

The US National Centres for Environmental Prediction agrees with the outlook, but goes on to add that the North-East monsoon rains would grow further in intensity during the second week of onset, from November 7 to 15.

It has hinted at a weather system (likely depression) originating from the South-East of Sri Lanka (South-West Bay of Bengal) and washing along the South Tamil Nadu coast.

A weather tracker employed by the US National Weather Services indicates this system may cross interior Tamil Nadu and Kerala and emerge into the South-East Arabian Sea where it might redevelop. But there is no consensus on exactly where this system would go, although some models find a track north-north-east towards the Gujarat-Mumbai region while others see it navigating to the open Arabian Sea.

Significantly, the Navy Global Environment Model sees a totally different track around Sri Lanka, but to its West (not the Tamil Nadu coast), and reaching the Lakshadweep Sea/South-East Arabian Sea where it may intensify.