True to forecasts, a low-pressure area may be building in the Bay of Bengal as early as during the next 24 hours (by Wednesday) thanks to typhoon Sarika that hit South China and Vietnam on Tuesday.

Westward-bound typhoons (cyclones) originating in the North-West Pacific/South China Sea are always expected to trigger some kind of response in the Bay that lies to the immediate west.

Onset window

Normally, a ‘low’ forming during the monsoon transition period such as this should help bring in the North-East monsoon.

But this is apparently being ruled out now, according to model forecasts. It would be at least another week before the ‘monsoon on retreat’ can set in over the South Peninsula.

This is so because the ‘low’ would most likely travel in a north-northeast track (father away from India’s coast) towards Myanmar, taking the rain with it.

Projections by the India Met Department (IMD) that the seasonal rains would materialise around October 26, at least six days beyond the October 15-20 timeline for normal onset.

Easterly wave

An ‘easterly wave’ with a rainhead upfront is forecast to cross in from the extreme East Bay of Bengal and head towards Sri Lanka/Tamil Nadu with associated easterly to north-easterly winds to bring in the rains.

Till then, a withdrawing South-West monsoon would set up thundershowers over extreme southern parts of Kerala and Tamil Nadu as per an outlook by the US Climate Prediction Centre.

The week beginning October 24 during when the North-East monsoon is expected to set in would see below normal rain for most of the peninsula, except parts of North Kerala and Coastal Karnataka.

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