The Sri Lankan Met Department has said that South-West monsoon conditions will get established over the island nation during the next few days (from June 3, Monday), marking a delay of at least 12 days from the normal onset of May 22. Sri Lanka is the penultimate pit-stop for the monsoon before it arrives over the Kerala coast in India.

Penultimate stop

Normally, it takes a week for the monsoon to advance from Sri Lanka to Kerala, but, as per latest India Met Department (IMD) forecasts, it may not take that long this year. On Friday, the IMD had not only retained the normal monsoon outlook during June to September but also reaffirmed the onset date over Kerala as 'around June 6,' as predicted earlier.

Related news:IMD retains normal monsoon outlook, reaffirms June 6 onset

But its own wind-field projections on Saturday morning suggest that a helpful monsoon onset 'vortex' (cyclonic circulation) would form off the Kerala coast by only June 10, bringing heavy rain into the State. Earlier, the Climate Prediction Centre of the US National Weather Service has hinted a below-normal rainfall for India and South-East Asia until June 11.

Also read:Below normal rain until June 11, may lead to mercury flare-up

Onset vortex

An onset vortex is known to occur over the mini warm pool over the South-East Arabian Sea off the Kerala coast where the sea surface temperature peaks just before the onset of monsoon. The vortex powers the monsoon onsets by several notches, but have become increasingly rare in recent years, due to the changing dynamics of the Arabian Sea.

In the instant case, the IMD projections show a northward movement of the vortex along the Kerala and Karnataka coasts, which would be the best thing to happen during the monsoon onset phase. But its onward track needs constant monitoring for signs of deviation to West-North-West or North-West, away from India's West Coast towards the open waters, which could affect the monsoon progress.

Meanwhile on Saturday, the Sri Lanka Met Department said that there is high possibility of enhanced showery conditions emerging to the South-West of the island nation ahead of the impending monsoon onset. Showers or thundershowers will occur at several places in the Western, Southern, Central and Sabaragamuwa provinces. Several spells of light showers will occur in North-Western province as well.

Weak over Andaman sea

Outlook until Sunday said that showers or thundershowers will occur at times in the seas off the coast extending from Puttalam to Pottuvil via Colombo, Galle and Hambantota. Winds will be South-Westerly speeding to 40 km/hr in the sea areas around the island. The speed can increase up to 55 km/hr off the coast extending from Puttalam to Trincomalee via Mannar and Kankasanturai and off Galle to Batticaloa via Pottuvil.

The monsoon is, however, weak over the Andaman Sea, South and East-Central Bay of Bengal and weather is partly cloudy elsewhere in the Bay, said the Myanmar Department of Meteorology and Hydrology. The Thailand Met Department too said on Saturday morning that the monsoon had weakened over the Andaman Sea.

The IMD said that conditions are favourable for further advance of monsoon into extreme southern parts of Arabian Sea, some more parts of Maldives-Comorin Area, and South-West, South-East and East-Central Bay of Bengal during next three days.

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