A low-pressure area has formed off the Kerala-Karnataka coasts, in the firmest yet indication about the strength of flows associated with the advancing South-West monsoon.

India Met Department (IMD) said this morning that the 'low' would intensify to become 'well-marked' over the next couple of days, likely precipitating the monsoon onset over Kerala.

'Low' materlialises

A prevailing circulation in the Bay of Bengal off South Tamil Nadu on the other side of the peninsula, which has been under watch for some time, has merged into the 'low' off Kerala.

Expectations are that the ceding of space by the circulation would only spawn a line-up of peer systems/'low's in the Bay, one after the other, during this week, fuelling the monsoon. The first of the series is expected to pop up over the East-Central Bay as early as tomorrow, driving the onset phase of the monsoon along with the counterpart off Kerala.

Meanwhile, a Myanmar Department of Meteorology and Hydrology has said that a 'low' has already formed over the South-West Bay. The monsoon over the South Andaman Sea in the neighbourhood, is 'weak to moderate' in intensity with a few clouds over the North Bay while being cloudy elsewhere, it added .

Synchronised seas

'Low's in the Arabian Sea and the Bay provide for a synchronised onset phase of the monsoon that has not been in view n the recent past. This is especially so given the fact that two predecessor cyclones had disturbed the monsoon build-up, diverting the flows and moisture away to Yemen and Oman.

Forecasts say the 'low' in the Arabian Sea could start weakening not too long after the onset and could slowly away, but the one in the Bay could become a depression. While the latter would be headed into Myanmar and Bangladesh, a successor or two developing in the Bay in its wake may cross the East Coast of India.

A third may also be there for the asking, all of which would help drive the monsoon into North-East, East and East-Central India and help it entrench itself there.

Monsoon advance

An 'amber colour' warning put out by the Met Department of neighbouring Sri Lanka said wind speeds around the island could race up to 60-70 km/hr right until Tuesday.

The seas extending from Puttalam to Batticaloa via Colombo and Hambantota can be 'rough' at times as the wind gusts could clock up to 80 km/hr during this period. This would coincide with the evolution of the 'low' over the South-East Arabian Sea off Kerala just to to the North-North-West of the island.

Meanwhile, IMD said that in view of the advance of the monsoon, squally weather would prevail over the South-East Arabian Sea over the next three to four days. Affected areas include Lakshadweep, Maldives, the Kerala and Karnataka coasts in the Arabian Sea side and South-East Bay of Bengal and South Andaman Sea on the other side.

Heavy to very heavy rain with extremely heavy rain is variously forecast for Kerala, Coastal Karnataka, Lakshadweep and parts of Tamil Nadu and Puducherry during this period.

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