The location and strength of the Madden-Julian Oscillation (MJO) wave may play an important role in the development of monsoon over India during the next several weeks, says the Climate Prediction Centre of the US National Weather Service.

The MJO wave is a global band of low-pressure area moving periodically from West to East, and determines the initiation and intensity of low-pressure areas/depressions/cyclones and also oversees monsoon onsets under its footprint.

Bay under watch

Cyclone ‘Vayu’ took advantage of an MJO wave traversing the West Indian Ocean and adjoining South Arabian Sea. The wave is now over the East Indian Ocean and adjoining Bay of Bengal.

This is what has prompted forecasters to scan the Bay for signs of storm initiation, with a rudimentary cyclonic circulation waiting in readiness over North-East and adjoining East-Central Bay.

The presence of the MJO wave is expected to wake up the circulation and prompt it to descend to the lower levels to set up a low-pressure area, which a storm tracker of the Climate Prediction Centre expects to intensify in due course as a storm.

Meanwhile, the US agency said that unusually warm waters in the Arabian Sea have set up a rare band of easterly winds over the Indian Ocean, which has significantly delayed the monsoon onset over the Kerala coast.

Dry spell seen

The Climate Forecast System model says a dry spell would continue over India through June 12-18 week and and most of June 19 Week-2 (June 19-25), delaying the monsoon onset over the rest of the country.

But during the second week and into the third, this models moisture cover over South India, likely signalling the arrival of a fresh pulse of the monsoon.

In the meantime, the India Met Department (IMD) has forecast widespread rainfall likely with isolated heavy falls over the Southern parts of West Coast and North-East India from June 18 to 20.

Isolated to scattered rainfall likely over the hills of North-West India, the Andaman and Nicobar Islands and the rest of the South Peninsula as well as East India during this period.

‘Vayu’ aftermath

Meanwhile, the lingering very sever cyclone ‘Vayu’ would bring to beat gale winds speeding up to 130 km/hr and gusting to 145 km/hr over the North Arabian Sea and the Gujarat coast in morning hours on Friday and decrease gradually thereafter.

The Sea condition would be ‘rough’ to ‘very rough’ (wave heights of eight to 20 ft) along and off the Lakshadweep-Kerala-Karnataka-Goa and South Tamil Nadu coasts and ‘phenomenal’ (46 ft) over the northern parts of East-Central Arabian Sea.

Strong winds with speeds reaching 40-50 km/hr are forecast over East-Central Bay and adjoining Andaman Sea as well as the South-West Arabian Sea off Somalia coast. This is indicative of fresh monsoon flows/storm genesis over the respective areas.

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