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.

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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.

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Uncertainty Continues In Northern Indian Ocean Weather

MAY 21, 2017, SUNDAY

As the southwest monsoon marshals its forces for an Indian entry into Kerala, doubts remain as to what will be the arrival like. Will it be steady, undeterred by a tropical cyclone gulping away some of its moisture and stamina? Or will an Arabian Sea tropical cyclone snatch away some its momentum as it veers off tangentially to Oman?

A Bay of Bengal/Arabian Sea storm is beneficial for monsoon rains in India if the system makes landfall into the indian coast. It acts as a locomotive which pulls along the rains into the country. A cyclone going to Myanmar or Oman is not conducive for Indian monsoon. They suck away considerable amount of the monsoon's energy and from an Indian perspective counterproductive.

Meanwhile the numerical weather prediction (NWP) models are taking us on a wild goose chase. Not only are they not agreeing with one another but contradicting themselves in successive data output.

The GFS was indicating a Bay of Bengal storm yesterday, is predicting an Arabian Sea cyclone today. According to it the storm will start off as a low near the Kerala coast on May 30/31 then intensify into something awful and hit Oman by June 6.

Meanwhile even the stolid, European ECMWF with their much vaunted supercomputers too seem to be confused. Earlier it was predicting an Arabian Sea cyclone going to southern Oman/Yemen. Now it foretells a depression in the Bay of Bengal on May 31 near the Myanmar coast.

Presently the Indian Ocean is in a state of tremendous flux as the approaching rainy system is creating massive turbulence. The utter anarchy of nature is such that even the biggest man made supercomputers are unable to discern any pattern. Simply put the supercomputers cannot make head or tail out of the prevailing situation in the ocean.

That is why we are seeing ever changing contradictory forecasts by the NWP.

The GEFS (Global Ensemble Forecast System) believes monsoon will hit Mumbai on June 4, 2017

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Storm Situation In Arabian Sea/BOB Remains Confusing

MAY 20, 2017, SATURDAY

Storm or no storm? That is the question. The Arabian Sea and Bay of Bengal has the entire international forecasting community confused.

Let us see first what the leading numerical weather forecasting models are saying what is going to happen in the next ten or so days.

The Canadian CMC model talks of a low pressure system moving past Sri Lanka eastward soon then re-curving back and hitting northern Tamil Nadu-southern Andhra Pradesh coast. It then crosses peninsular India, emerges in the Arabian Sea and intensifies into a tropical cyclone.

The American GFS predicts a low pressure area forming in the Bay of Bengal on May 22. This may enter Andhra after a few days and end up near Mumbai/South Gujarat on May 29. Ot it may move past Odisha coast and hit West Bengal/Bangladesh by the month end.

Confusing. Confusing.

The European model ECMWF says no Bay of Bengal storm. An Arabian Sea system may form on May 25-26. Where it goes? Perhaps Oman. Perhaps Yemen.

The Indian Meteorological Department is bullish on a Bay of Bengal low pressure system developing on May 22-23.

The ensemble forecast of the GFS is supporting a Bay of Bengal depression/cyclone hitting Andhra Pradesh near Visakhapatnam. Hence we can safely say there is a good possibility of this happening. The American agency Climate Prediction Center too says the same thing.

Just look at the CMC and GFS forecasts below. It explains the prevailing confusion.

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Arabian Sea, Bay Of Bengal May Spawn Storms Soon

MAY 19, 2017, FRIDAY

We had predicted that the Madden Julian Oscillation currently passing by the Indian Ocean may throw out a tropical storm or two in the coming days. That seems to be happening. But when and where? That seems hazy at present.

The European forecast agency believes a low pressure system will develop in southern Arabian Sea on May 24. This will intensify into a tropical cyclone and may hit central Oman near Duqm on May 28. But this is not yet supported by other global models.

The American agency NCEP thinks a slow moving low pressure system will develop by May 21 in the Bay of Bengal near Andaman Islands. Other models suggest the expected system will form later around May 28. Where it goes is hard to say now.

The result of these storm antics? The monsoon will arrive in Kerala only after the Arabian Sea cyclone reaches Oman. Though the slow moving Bay of Bengal storm may push the rainy season into India earlier.

Let us see what does happen. The window of opportunity for tropical cyclone formation in the Arabian Sea, BOB closes by May end. The Madden Julian Oscillation will then pass over into the west Pacific region.

The names of the two tropical cyclones will be MORA, and OCKHI.

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