Tuesday, May 27, 2014

Monsoon Watch - 5...28th May 2014

SWM has further moved into  Maldives and Northern Andaman Sea.

Cross Equatorial Flow

has picked up considerably in the Bay. In fact it is showing an independant trend, disassociating itself from the Arabia Sea branch. Winds around 30 knts (40 last year) are seen gushing Northwards off the Somali Coast, and 30 knts winds are also seen in the Bay.
Winds off the Sri Lanka coast are picking  up considerably.
But the Arabian Sea banch is dis organised and shows no definite formations from the Somali coast to the West Indian coastline. 

Today's SST map

reproduced here to show the Sea temperature falling  along the Somali coast. It is presently around 23c (20/21)c. { Brackets indicate last year's readings}.

Now, this difference with the Central Arabian Sea plays a key role in cloud formations off the Western Coastline of India in the Central Arabian Seas. The SST along the Somali coast should rapidly fall to around 18/20c in the next 10 days.

But the present fall is not sufficient to help form Monsoon clouds around the Central Arabian Sea. Cloud formation near Sri Lanka is slow, and in next 3/4 days, wind speed along the Sri Lanka coast is estimated at 35 mph (in gusts). 
A slight fall is seen in the Bay water's SSTto 30c.

The ITCZ is slowly moving up, but is still around the Equator, and in the 7N region in the Bay sector.

The Seasonal Low seems to lack strength. We see today's pressure at 1002 mb (998). Taking time to gradually ready enough to create a gradiant to pull up SW winds into the mainland. The day temperatures on the Sub-Continent Northern plains are on the lower/average side from this week with the average the day's highs are around 41/43c (43/44c). 

Across in Pakistan' Sindh region, the core area for the formation of the low, the highest had already crossed 50c last year. 
Now, with the first meaningful heat wave getting underway in the Northern regions of the sub-continent, we can expect the seasonal low to develop in the 

Sindh/Rajasthan region and attain a core pressure below 1000 mb at a rapid pace. By next week, we can hope to see 998 mb in the Thar Desert region. 
And with a systematic rise in wind speed in the S.Arabain Sea, SWM clouds could form by early next week in the Cetral Arabian Sea and off Sri Lanka.
SWM, as a weak current, should set in over Sri Lanka within next 3/4 days, that is by the 31st May. 

WDs should slow down now, as the jet streams at 200 hpa are re-grouping  into position. The Jet Stream Westerlies are almost upto the 10N line (15N), and the "High" formation is taking shape East of Bangladesh. Expected placement of this "High" should be inland towards MP for perfect position.

The Bay sector SWM has been stagnant, and not picking up as expected from a "setting in" Monsoon. 
As SW winds lack speed,no Low could form in the Northern Bay. In the next 3/4 days. UTH map show no concrete formation either in Bay or Arabian Sea next 5/6 days.
Better this happens before another WD reaches the region to spoil the "party".

Changes in 850 hpa winds ( and anomalys) show a weak MJO pattern.

Weak in our seas till 5th June, but strengthening to neutral (not strong) from 5th to 16th June..and going back to weak as the wave moves Eastwards.

As the SSTs are warming up, the El Nino conditions in Nino 3.4 are slowly building up. vagaries maintains a full El Nino will be in place after August 2014.
Rainfall will be almost around normal for Southern India and peninsula in June , and weaken after August. But Northern parts of Sub continent will see enhanced rainfall in the second half of the South West Monsoon.

Conclusion: Things have changed drastically in the last 10 days...or can we say, things have not developed in the "normal" speed , and in fact the SWM progress is hampered.
SWM advancing into Sri Lanka as a weak current by 31st May. 

Due to persistent ridge in the Arabian Sea till 3rd/4th June, and a High pressure zone in the 700 mb level in mid Arabian Sea, any formation of a low or system in the Arabian Sea till 6th June is difficult. MJO is also not favourable.

A trough along the West coast off the Kerala coast forms by 31st May or 1st June.. 

SWM Advance into Kerala around 2nd June. But, further advance would need monitoring. Possibly into Coastal Karnataka/Goa and Southern TN regions by the 5th of June. South Konkan and interior Karnataka ( Bangalore) around 7th/9th June, and North Konkan, South Madhya Mah (Pune), Mumbai by 10/11th June.
SWM advance into NE States by 2nd/3rd June and Kolkata by 10th June.
Marathwada and Vidharbh will get the Monsoon advance after 15th June..

Hot in Central India , NW India and most of the Plains of Pakistan till 20th June...SWM can cover India by end of June and enter Pakistan in 1st week of July.

Keep Checking Monsoon Advance Position in vagaries.


(This Monsoon chase is my personal view, and my personal analysis and deciphering is done as per my assumptions. Should not be used for commercial purposes). 


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The 7th vagaries' meet will be held on 31st May at the Upvan Lake, Thane. All are requested to attend....We will be discussing the next field trip to IMD Pune, and IMD Mumbai Doppler Chief Mr. S.Kamble will be attending. All are requested to be there on time at 5 pm IST....Please confirm attendance.





5 comments:

Abhijit said...

Vagarian Santosh Subramanian reports us on Kolkata weather.

A record cold day for Kolkata on a Summer Day :-
27th May 2014 Max temps :-
Alipur : 27.0 C (-8 C below normal)
Dumdum : 28.9 C (-6 C below normal)
Kankurgachi : 27.5 C
coollllllll!!

Total Mean Rainfall for Kolkata in the month of May is = 136.6 MM
Till date Kolkata in May 2014 , Has received =
Alipur : 87.3 mms
Dumdum : 84.3 mms (Till 27th May 2014)
Still around 51 mms to cover up , though i feel , that that deficit would be covered today ..

Abhijit said...

Today evening from 4pm onward suddenly sky turn dark with strong winds from NE and then was followed by moderate to heavy rain for 20mins in Badlapur.

Badlapur recorded 9mm rainfall till 5.30pm today and temp was drop to 25.7c while time of storm at 4.30pm.

Karjat AWS recorded 2mm rainfall and temp was drop to 24.6c while time of storm.

Junaid from Panvel reported light thundershower for 10 mins period.

Abhijit said...

Western Maharashtra was also lashed by Thunderstorm today afternoon..

Many parts of Nashik & Pune city reported Hails. Hadapsar in Pune received Hails..

Some rainfall details till 5.30pm today :

Satara 44mm
Solapur 23mm
Sangli 19mm
Nashik 12mm
Pune AP(Lohagaon) 8mm
Kolhapur 4mm
Pune city 2.8mm
Mahabaleshwar 2mm

Vinod said...

Wow when will mumbai get some rain..

Atul Naik said...

Presently enjoying freezing dry weather at 700, 500 hPa in Leh, Ladakh! But reports from home in Goa indicate more than usual pre monsoon shower activity, but still expectations of a late SWM onset.