International weather models have hinted at the possibility of a storm developing in the Bay of Bengal within a week’s time.

This will happen as a weather-generating Madden-Julian Oscillation (MJO) wave departs the East African coast to trigger activity quite some distance to the east in the south-east Bay of Bengal.

‘Low’ expected

The MJO wave travels in the upper air but dictates weather over ground by organising thunderclouds under its footprint. The wave can oversee formation of low-pressure areas that might go on to set up storms.

Movement of the wave is also closely watched during this time of the year since it can also set up right conditions over ground for monsoon onset.

A US Navy model said that south-westerly winds may gather pace over the Bay of Bengal in a couple of days and drag the monsoon current over the islands around the scheduled time.

The winds are forecast to curve in over the Andaman Islands to set up a low-pressure area in due course. The ‘low’ is initially forecast to head towards Myanmar, the US Navy model said.

Rain spurt

But it will merely graze the south-west Myanmar coast and slip right back into the sea to strengthen at a location almost equidistant from the Bangladesh coast and Gangetic West Bengal in India.

The US National Centre for Environmental Prediction too seemed to agree with this prognosis and suggested that this might coincide with a sudden spurt in rain activity over peninsular India.

But this is not to be taken for the onset of the Arabian Sea arm of the monsoon that hits mainland India along the Kerala coast around June 1.

In fact, this model goes on to predict a second spell of rain over the Kerala coast that it believes could gradually precipitate the onset of monsoon towards the end of the month.

Early onset?

It seeks to build a scenario where the monsoon could set in a few days ahead of the normal date of June 1.

The European Centre for Medium-Range Weather Forecasts refrained to put out a storm watch in the Bay just yet but agrees that a broad area of lower pressure may build there from mid-May.

It sees south-westerly winds suddenly whipping up pace after May 21 around in south-west Bay of Bengal and lower pressure starting to establish in south-east Arabian Sea in tandem.

These are conditions normally taken to signal that the seas are preparing themselves to host the monsoon current and connect it onward with mainland India.

India Met Department has already forecast that seasonal rains would be below par this year thanks to the lingering El Nino shadow.

(This article was published on May 13, 2014)
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