Saturday, October 22, 2016

Posted Saturday Night....10.30 pm IST:
BB-14 moved E/NE from our last report, and is located currently at 15N and 92E. Estimated core wind speeds at 25kts. 
Expected track is NE, and intensification expected.

Vagaries sees reducing and decreasing possibility of significant re-curving after reaching Myanmar coast. If at all it re curves, it will start to weaken considerably.

NEM is delayed till at least end October...

Thursday, October 20, 2016

Vagaries Views..Posted Friday Night:
BB-14, a depression with estimated core pressure at 1000/1002 mb and estimated core winds at 20-25 kts , is located at 14N and 90 E. Seemingly stationary, but has taken an anti clockwise loop and come back to yesterday's position.

Divergence at the 200 levels is seen, thus and along with vertical wind shear over the core region, we expect further intensification of system. Will become a Deep Depression by Saturday, and in all likely hood a cyclone by Sunday/Monday.
Expected to track E/NE towards the Myanmar coast near Pathein. 

As the system intensifies off the Myanmar coast, 200 level winds guidance and no 500 level ridge resistance will steer the stem BB-14 from th Myammar coast to re-curve and track NW towards the Bengal coastline.Expected there by around 25th October, depending on the re-curve spped.

In this scenario, the NEM can get delayed beyond the expected 24th date...

Posted Thursday Night:

A well marked Low, BB-14, has formed in the Bay, at 14N and 90E to be precise.The UAC from BB-14 extends to the Upper Air levels.
Currently, the convection and precipitation is in the SW quadrant, along with maximum winds at 20-25 knts. 

This system is likely to deepen into a depression in the next 24 hrs. 
Some International Models suggest BB-14 to move in a NE track and towards the Myanmar coast. The system then hits the Myanmar coast and moves inland.
Another Forecasting model makes the system just graze the Myanmar coast around the 24th, and then forecasts a W/NW track towards Odisha on the Eastern Coast of India.Another forecast, in agreement with IMD, suggests the system to go towards Bengal after the brush with Myanmar.
One particular model forecasts a direct track NW towards the AP/Odisha coast.
These various track estimates are based on certain uncertain Upper Winds and STR at 500 level, which is positioned in far West today, and the tracks of 2 consecutive WDs.

Since I am unable to estimate the track of this puzzling BB-14, would like to read comments on possible track from readers. Please post your views by Saturday.

Tuesday, October 18, 2016

Mumbai.....Starting to Feel the Heat ??

Well, See last year ( and 2014 October for comparison) this time Here and Here...and compare...Last year was the Hottest October ever at Scruz and the Warmest October Night ever at Colaba !

Monday, October 17, 2016

With the 2016 rainy seasons hesitating to change between the SWM and NEM, a brief Summary of the NEM.

-The SWM onset is well defined, and follows a well coursed out Northward progress. And can be discerned with reasonable accuracy on charts.
For the NEM, it is not so.
In fact, on many occasions, there is no clear indication between the withdrawing SWM and setting NEM. Often one tends to merge into another.
So, setting a date for the commencement of NEM is difficult, and sometimes not possible.

-The main has its origin, its "Power House", is at the Mascrene Highs off Madagascar. The NEM has its origin round a large anti-cyclone over Siberia.

-The Upper winds during the NEM across the Bay are in a clockwise direction.That is an anti-cyclone is formed. At a level of 500 mb, the centre of the anticyclone shifts to central Burma region.
-The Upper Air temperatures show a Northward gradient in the NEM.Near 10N it is normally warmest, and dropping by 8c at 30N.

-Jet streams at 200 hpa are common to both the monsoons.
In the SWM, the Tropical Easterly Jet stream dominates the Peninsula, while the Sub-tropical Westerly Jet Stream is the feature of the NEM.

-The normal Sea Level Pressure during the NEM is a large system of low pressure over the Central Bay. It can extend into the Indian Peninsula as a trough.Towards the end of November,there is a shift southwards of this extended low.
-The general variations and fluctuations in intensity of this low pressure, governs the rainfall. When the trough is well defined, and the low is well marked, rainfall over the southern peninsula is good.
-During the NEM, an occasional burst of cold air from the Siberian High develops a low pressure sysytems over the Equatorial regions of the South China Seas. These systems move slowly westwards thru Sarawak/Eastern Malaysia coast, and remnants of these cross over into the Bay and form depressions.

Most of the NEM rains depend on depressions and cyclones from the Bay towards the East Coast of India.

The advent of the NEM is getting  delayed this year.
Vagaries predicts its advance around the 24th. taking into considerations the withdrawal of the SWM. The SWM lingers on, and even today, on the 17th, is still prevailing over parts of Karnataka and T.N.

The overall delayed actions, beyond forecast estimates, is mainly attributed to the stubborn SWM, and to some extent the weak MJO not "supporting" the fast formation of NEM currents in the Bay. Cooler SSTs are long overdue west of Java and Sumatra.

But, the upper winds are showing signs of "resigning" and changing. The Mascrene highs have lost their grip, and are seasonal and weaker, and the Tibetan/Siberian High is taking shape ,though late.

Friday, October 14, 2016

Monsoon withdraws from Mumbai....
Withdrawal Position on 14th October....

Heavy Rains in Kerala and adjoining T.N....( As estimated ..See reason in Monday 10th Oct Post)

Amounts from PJ....

Thursday, October 13, 2016

Posted 13th October Thursday Night
Technical Withdrawal Line of South West Monsoon...Images below give the explanation..
For Mumbai, though technically not in the withdrawal region, the Monsoon is as good as withdrawn...and Withdrawal for Mumbai will be announced here by 15th, as the 200 level winds change and UTH drops, along with favourable (for withdrawal) level drop of OLR .