Arabian Sea may throw in own surprise ahead of monsoon

Vinson Kurian Thiruvananthapuram | Updated on May 25, 2020

Several global models have suggested that a persisting circulation could be a potential harbinger of the monsoon into mainland India.   -  IMD website

Cyclonic circulation off Kerala coast bears watching

The Bay of Bengal may have seen off super cyclone Amphan that brought the monsoon into the South-East Bay, and the Andaman & Nicobar Islands earlier this year. It now appears that the Arabian Sea may be waiting to throw in its own surprise ahead of monsoon onset over the Kerala coast in mainland India.

The India Meteorological Department (IMD) has factored in a delay of four days and has said that the seasonal rains would arrive in the State around June 5 with a model error of four days. A rogue circulation, likely emerging midway off Somalia, is what is currently seen as throwing a spanner into the monsoon works.

Likely low-pressure area

However, a persisting circulation nearer home over the South-East Arabian Sea, off Kerala and over Lakshadweep, has been engaging the IMD’s attention for several days now. Several global models have latched on to it, portraying it as a potential harbinger of the monsoon into mainland India.

According to them, it would convert itself into a low-pressure area into the first week of June, and could go on to intensify over the warm waters of the South-East Arabian Sea around Lakshadweep.

The sea surface temperatures there are 30-31 degrees Celsius, ideal for its further growth even into a storm.

The IMD has said that heavy rainfall may break out at isolated places over parts of the South Peninsula from tomorrow (Tuesday) to Thursday. From Saturday (May 30), it would be scattered to fairly widespread over Lakshadweep and the southern Peninsula, and heavy- to very heavy- over coastal Karnataka and Kerala.

Maldives rain trends

Meanwhile, the monsoon pieces are falling right into place elsewhere over Maldives where all indications are that the rains may have established. The normal timeline of onset is mid-May. Scattered showers and few thunderstorms have been forecast for the country, to the South-West of Sri Lanka.

Winds will be south-westerly/westerly at 8-24 m/hr in the southern atolls and west/northwesterly elsewhere at 16-32 km/hr. Winds may gust to 64 km/hr during showers. The seas will be slight (wave heights of up to 4 ft) in the southern-most atolls and moderate ( 8 ft) to rough (13 ft) elsewhere.

The monsoon establishes first from the southern atolls and propagates northward. Global forecasts say that the northern and central atolls may receive normal rainfall in May while it would be above normal over the south.

June-September may see above normal rainfall (+10 per cent) across the atolls.

Heavy rain, high winds over Lanka

Sri Lanka, the penultimate stop for the monsoon before it hits Kerala, would witness showers or thundershowers at several places over the western and the Sabaragamuwa, central and southern provinces today (Monday).

Heavy falls above 10 cm are likely at some places along the western slope of the central hills.

Winds will be monsoon-friendly south-westerly reaching speeds at 30-40 km/hr over the seas around the island. The speed can clock at 50 km/hr and even 70-80 km/hr in the deep and shallow sea areas off the coast extending from Puttalam to Kankasanturai via Mannar, and Matara to Potuvil via Hambantota.

Published on May 25, 2020

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