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...