The South-West monsoon has advanced into the deltaic areas of Myanmar, at least six days behind schedule (normal onset is between May 21 and 25), the Myanmar Department of Meteorology and Hydrology said. In an update issued today morning, the Myanmar Met said that the monsoon has also advanced into parts of South-West and East-Central Bay of Bengal.

Untimely ‘Low’

India Met Department (IMD) has already mentioned about the monsoon entering the southernmost parts of Maldives-Comorin, more parts of South-West and South-East Bay, remaining parts of the Andaman Sea and the Andaman Islands as well as some parts of East-Central Bay.

The monsoon is moderate over the Andaman Sea and the South-East Bay this morning, the Myanmar Met said, with a few clouds over the South-East and South-West Bay and partly cloudy to cloudy elsewhere in the Bay. The Maldives Met Service said this morning warned of fairly widespread rain with occasional heavy showers and thunderstorms over the country.

Surface winds will blow in monsoon-friendly direction from the South-West/West at 20- to 37 km/hr over the central atolls, but from West/North-West at eight km/hr to 24 km/hr elsewhere. This is attributed to an an untimely low-pressure area off the Horn of Africa, from where the monsoon winds originate. Monsoon winds have to be Westerly/South-Westerly as they blow in towards Sri Lanka/India.

Onset over Lanka

According to wind-field projections put out by the IMD, this 'rogue' circulation may not last for long, and proper Westerly to South-Westerly flows would revive by June 4/5. This could go on to precipitate the monsoon onset over Sri Lanka by June 5/6 (late by more than 10 days), apart from setting up a circulation around the Maldives that could bring the monsoon to Kerala and mainland India.

A 10-day outlook put out by the Sri Lanka Department of Meteorology also suggested a sustained flare-up of high winds and heavy rain along its south-western flanks from June 5/6. As for today, it said that showers or thundershowers will occur at times in the sea areas off the Sri Lanka coast extending from Puttalam to Pottuvil via Colombo and Galle.

Heavy showers can be expected at some places in these sea areas. Winds will be South-Westerly and the speeds could range between 20- to 40 km/hr around the island. Wind speeds can accelerate 55 km/hr at times in the sea area off the coast extending from Puttalam to Kankasanturai via Mannar and in the sea area off the coast extending from Galle to Batticaloa via Pottuvil.

Wind directions

The sea extending from Galle to Batticaloa via Pottuvil can remain 'fairly rough' today. Overall, these conditions represent a good build-up to the monsoon. A shipping forecast issued by the Sri Lanka Met said that moderate South-Westerly winds would prevail over the Maldives and South-West Bay of Bengal. It would be North-Westerly over the Lakshadweep, though.

Occasional showers or thundershowers are forecast for Western Sri Lanka, the Maldives and South-West Bay. Scattered showers is likely elsewhere over these areas. The seas would be 'fairly rough' and 'rough' (wave heights ot 8- t0 13 ft) at times over the Comorin, 'moderate to fairly rough' (4- to 8 ft) at times off Maldives and Western Sri Lanka.

Meanwhile, it remains to be seen whether the circulation likely developing around Maldives by June 5 would go on to intensify and track towards Oman/Yemen. This could weaken the monsoon flows headed to India in the process, especially if it were to become a cyclone, as has happened during the monsoon onset phase in the past. Most global models have ruled out this probability, although the Climate Prediction Centre of the US National Weather Service has hinted at a 'low risk of cyclogenesis' in the Arabian Sea.

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