Monsoon To Enter Kerala By May 30, Mumbai By June 8

MAY 23, 2017, TUESDAY 

Looking at forecast charts by global Numerical Weather Prediction models one can safely say that the southwest monsoon is set to arrive in Kerala by May 30, 2017. Our estimate is it will hit Goa by June 4 and Mumbai by June 7-8.

The monsoon onset we are talking about as decided by parameters set by the indian Meteorological Department. If we were to go by amount of rainfall alone, heavy thunderstorms will start lashing Kerala in the next 3-4 days.

According to accumulated rainfall forecast charts by the European agency, ECMWF, by June 1, parts of Kerala will have received a whopping 334 millimetres of rain. Monsoon is expected to cover coastal Karnataka by June 1 itself.

After the Kerala onset, the rains will clamber up the latitudes quickly and reach Mumbai by June 8. Fortunately for Indian monsoon this year there have been no depressions/tropical cyclones in either the Arabian Sea or Bay of Bengal which suck away its energy and throw it in another direction, thus slowing down its progress.

There is little possibility of a storm in the seas except for a Bay of Bengal upper air cyclonic circulation which may intensify to a low pressure area/tropical storm by month end. But even that is expected to move into Bangladesh/Indian northeast, thus it will actually hasten monsoon's entry into eastern India.

According to the ECMWF forecast rains will be knocking on Goa's doorsteps by June 2.

Monsoon arrival means massive changes in upper atmosphere winds, some 12-13 kilometres high in the air. This June 1 forecast map shows the monsoon winds are already blowing over peninsular India. The perennial easterly jet stream has been pushed northwards into Tibet. This occurs every year during monsoon time.

There is sobering news for those expecting a bumper harvest this year. In it's latest forecast the Bureau of Meteorology says the Indian Ocean Dipole may not be so positive in August. In fact the European model predicts a weak IOD this year.

Similarly NASA and the ECMWF says El Niño may rear it's ugly head by August. Only NOAA paints a rosier picture. Be prepared for poor rains in August-September unless of course the picture changes by then.

Monsoon To Intensify From May 29

MAY 22, 2017, MONDAY

After May 20, the buildup of the monsoon has begun. In the Arabian Sea the coast off Somalia has become increasingly stormy with many clusters of thunderstorms. This activity will over the next few days shift eastward towards the Maldives, nearer to the Indian coast.

On the Bay of Bengal side the seas west of the Andaman Nicobar islands is becoming increasingly stormy. A low pressure area may develop here in the next 24 hours.

All this is just a curtain-raiser to the main event. The monsoon assault on the Indian mainland.

The arrival of the rainy season this year will occur on two fronts.

First the Bay of Bengal will spawn a big rainmaker low pressure system in northeastern part of the sea on May 29.

Secondly, the Arabian Sea will go into a massive ferment off the Kerala-Karnataka coast from May 29-30. That will result in the monsoon hitting Kerala. Not only that. That area may spawn a low pressure system. Some forecast models are already predicting that a massive tropical cyclone will emerge from that.

More on that later. Because the storm situation in the Northern Indian Ocean has not yet become any clearer. We have to wait. 

Personally we think the chances of a tropical storm either in the Bay of Bengal or Arabian Sea is decreasing as the Madden Julian Oscillation is moving away from the Indian Ocean. We may at most get a low pressure/depression in the Bay of Bengal. That too is not certain.

Some Signs That Monsoon 2017 Is Preparing To Come

APRIL 17, 2017, MONDAY

The south west monsoon is still about 40 days away, before it arrives to an eagerly awaited welcome to the Indian subcontinent but we can discern some signs that hint at its arrival.

The first is the strong almost daily thunderstorm activity in the Indian North Eastern states, like Assam, and also in Myanmar and Bangladesh. The daily precipitation in these areas started almost a fortnight ago. A look at accumulated rainfall forecast by the reliable ECMWF model reveals that in the coming days the pre-monsoon activity is going to become very vigorous.(SEE FORECAST MAP). Moreover the thunderstorm activity is becoming vigorousl in south eastern Bay of Bengal from where the monsoon enters each year.

Secondly, the wind direction in the Bay of Bengal and Arabian Sea has reversed in the last few weeks as the winter northeast monsoons have long departed. The winds are beginning to blow in Gujarat and parts of Sindh from the Arabian Sea. As strong pre-monsoon winds push up from Somalia.

Similarly in the Bay of Bengal moist winds are moving up north hitting Myanmar, Bangladesh and India's North East bringing pre-monsoon thunderstorms in these areas. The recent tropical cyclone MAARUTHA is going to act as a catalyst speeding up the arrival of the monsoon.

The CFS model has predicted that pre-monsoon activity is going to start in Gujarat, Sindh, Maharashtra and parts of Rajasthan in mid May itself.And that monsoon is going to become vigorous in both the Arabian Sea and Bay of Bengal from June 1, 2017 itself. Both the seas are going to throw out at least a tropical cyclone/depression/low pressure system each in June. Good rains are expected in Odisha, Gujarat, Sindh and Oman in June.