The India Met Department has warned of heavy to very heavy rainfall for the peninsula for next three days under the influence of a low-pressure area taking shape just off the Kerala-Karnataka coast.

The ‘low’ is expected to materialise over the south-east Arabian Sea and adjoining coasts of north Kerala and Karnataka as early as Saturday, the Met said on Thursday.

Enabler zone

A preparatory upper air cyclonic circulation over south interior Karnataka has now moved west to the Lakshadweep-Comorin area and is embedded into an east-west shear zone of monsoon turbulence.

A key monsoon enabler, the shear zone features opposing winds in an area rising from three km and six km into the atmosphere.

This is the height where the monsoon is most active in the atmosphere. The shear zone also sets up the platform for rain-bearing systems (low-pressure area) to play around in.

The current scenario nearly depicts normal monsoon onset conditions, replete with a rain-friendly Madden-Julian Oscillation wave transiting the region in the higher levels of the atmosphere.

Rain outlook

Given this, the peninsula is forecast to slip under a pulsating wet spell especially along the south-west coast covering Kerala and Karnataka as also the Lakshadweep islands.

In fact, the Met forecast heavy to very heavy rainfall for Lakshadweep for Thursday. Heavy rain was also forecast for entire Karnataka, Kerala, Tamil Nadu, Puducherry, Marathwada and Madhya Maharashtra.

Beware Karnataka

A warning sounded for Saturday said heavy to very heavy rainfall with extremely heavy falls could batter coastal Karnataka. Heavy to very heavy rain has been forecast for Kerala and south interior Karnataka.

Heavy rain has been forecast also for Madhya Maharashtra, Marathwada, interior Tamil Nadu, Puducherry and Lakshadweep.

Meanwhile, an outlook from the US National Centres for Environmental Prediction shows the low-pressure area clambering up along the edge of the coast up to Goa-Konkan and getting dissipated.

It also indicated the possibility of the eastern end of the seasonal trough now hugging the Himalayan foothills reverting and dipping into north-east Bay of Bengal by Wednesday next.

It remains to be seen whether it can dig out a low-pressure area from the seas, which can fan monsoon winds back into the plains of north-west India.

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