Saturday, May 14, 2016

Monsoon Watch -4.....15th May 2016

Though a bit late, the important parameters have improved and become "Positive" after our previous MW-3. Seeing the development now, I would vouch for the Monsoon arrival date for Mainland Kerala mentioned in MW-3.

1. Seasonal Low: Indicator: +ve
The heat is on in the Gujarat, Rajasthan/Sindh regions from the last 8 days, so chances for the seasonal low to form and establish itself soon.Today the pressure at MSL is 1002/1004 mb, with the core at 1000/1002 mb. Gradient not enough.
The sub Continent hot spots have just about touched the 48c mark in Pakistan (Balochistan/Sindh) and around 47c in India. 
Should head for the 50c mark in Pakistan between 21st-25th May.

2. ITCZ: Indicator: Normal
BB-1 has got the Eastern end of the ITCZ Northwards, and very favourable for the Monsoon  (Bay Branch).

3. Jet Streams: Indicator:-ve
Easterly flow has now commenced at 8N.Western Disturbance M-3 will slightly upset the Northward track of the 200 hpa Easterlies.

4. Cross Equatorial Winds: Indicator: +ve
Well established in the Southern Hemisphere region. SE winds, with sufficient speed hitting the East African coasts, and gaining sufficient speed as Westerlies South off Sri Lanka.
Winds are now picking up, and rubbing the Somali coast at sufficient speed in getting the "Somali Current" established. 
The SST off the Somali Coast is 23/25c, While the required SST in First week June is 19/20c. (Required to form masses of Monsoon clouds in the warm central Arabian Sea).
The Bay Low has formed...in good time, and BB-1 is helping the Bay Branch of the Monsoon.


5. ENSO factor in arriving at the rainfall amount is also of importance. The interface is the sea surface: that is where the transfers of water (evaporation/precipitation)  and momentum occur. (An accurate coupling of the fast atmosphere to the slow ocean is essential to simulate the ENSO, which in turn can simulate the inter-annual variability of Indian monsoon.) Unfortunately, getting an accurate, or near to accurate forecast of the ENSO for the next 2 months is difficult, with no guarantee of accuracy or performance surety.
We still see El Nino lingering now. But, there is a possibility of a Neutral event occurring as early as July. Now, this would result in enhanced rainfall from July/ August. That is the best thing we want. But I would not endorse the timing of the event as yet. I would give it a 50-50 chance for Neutral ENSO by June/July.

Pulses from the Eastern Pacific area, that is S.China sea, would mean depressions and systems forming in the Bay. 'In Situ" systems and systems from the Far east would contribute to the rainfall to the east Coast, move  thru Central India and into Gujarat and even into Sindh (Pakistan). El-Nino, even a mild one like the current May condition, would sort of restrict these pulses, and in fact encourage WDs into coming down south, more South than normal. 
But, we would have to hope and pray for the Neutral conditions to prevail by June/July and hang on beyond September. again.

Rainfall Estimate for Monsoon 2016 for India and Pakistan will be published here in MW- 4 (Additional) on 20th.May...

12 comments:

abizer Kachwala said...

Rajesh sir,I agree that i have referred to a site showing weather forecast that was the bbc weather which is reliable,besides various weather forecasting sites such as accuweather,weather channel ,etc are non reliable and they give non-reliable and erratic forecasts.As we all know that it isn't that easy to predict nature.I am 14years old ,i have been following your forecasts since 2012 ,i have learnt many things from your forecasts,and have found that almost all your forecasts have turned into reality.Its not easy to give a steady forecast unlike others who withdraw their forecasts every minute,your forecsts are appreciable and worth praising!!!

Karan Kumbhar said...

Sir
IMD predicts a delayed onset over kerala (7TH JUNE). Any changes in monsoon arrival dates from your side ?

rajesh said...

abizer: I shall encourage and guide you as much as possible. Be free to ask.

Hrishikesh said...

Sir what about Mumbai and Lonavla for 18th-21st can we expect rain?

emkay said...

BBC weather predicted earlier than normal swm today on mainland, IMD says 7 days delay, Rajesh bhai sticking to normal arrival- so it's an interesting situation

rajesh said...

Karan/Emkay: I have mentioned in MW-4, the article above, that I keep the SWM arrival date for Kerala as mentioned in MW-3 of 5th May...the date for Kerala was announced as 4th/5th June in MW-3.

Hrishikesh: Can expect rain on that date depending on the movement (if) AS-1 forms as mentioned.

Karan Kumbhar said...

Thank you sir
Didn't read that part
Irrelevant question !

Zohair said...

Great work as usual, and thanks a lot sir for mention sindh seperately, :)

Zohair said...

Do u think all other regions will also see delay in onset?

kako sehr said...

Subsurface waters anamolies of Pacific put la nina as more favorable to la nada for mid July and after wards. Though u don't consider but negative iod is likely to be moderately to highly negative during swm 2016 which is biggest threat to swm 2016. I think swm 2016 is likely to be 10-15 % below normal, if not then above normal ms is absolutely unlikely to happen.

Nilay Wankawala said...

Where as vow 's MW 4 arrives on time, and sir releasing arrival date well in time in MW 3, IMD has announced late arrival of swm 2016 into kerala yesterday by 6 7 days. This is the accuracy timeliness and perfection of Rajesh sir forecasts....great work sir....you are always a true leader in forecasting from all perspectives. ...

Zohair said...

how does western pacific effects on MonSoon? least cyclones during La Nina/Neutral? or movement of cyclons?