Tuesday, May 04, 2010

 Monsoon Watch - 5
The parameter of utmost concern to me now is the Bay factor. The consistently -ve factor from the very first MW.
The latest winds in the Bay continues to show strong winds rushing Northwards along the East coast of India, into the trough lined up in the North-East. The North-West flow of winds into the Myanmar coast also exists.
Also, the SST in the Bay is now very conducive to host a low anytime now.
In fact, on comparing the Bay SST on this date last year,(Maps from NOAA) we can see how much hotter the waters are this year.( Last year, 2 cyclones had cooled the waters of the Bay). A low, according to me, should have normally formed by 15th. April. 
Now, the delay in the formatiion of the wanted Bay low is due to non active movements of MJO towards the East from western Indian Ocean..
Also, according to ECMWF forecasts, and other models,no low is predicted in the Bay till the 11th.May at least.
Indicator :-ve
 The 200 hpa jet stream. Normally, they should be Easterlies right upto 20N by May end to facilitate the Northward movement of the Monsoon Current. Today, the jet stream is developed upto the Equator, but is stationary. These jet winds need to get organised soon, and come upto 8N by 2nd.week of May at least, and then move upto 10N before 20th.May, to be in time for the Andaman Sea Monsoon arrival. 
With the heat continuing in the Northern regions,the Seasonal Low in the Thar Desert is deepening, with a core pressure now at 998mb, and spread over a wider area. (See Thai Met Dept Map). And this is perfectly forming as per schedule.
Moisture inflow  into Kerala and South Karnataka has now lessened. As mentioned in my MW previously, this is absolutely necessary for the creation of a good gradiant between Kerala pressure and Rajasthan/Sindh pressure. And that is a must for creating a pull Northwards for the Monsoon. Overall position in this parameter is much improved since MW-4.
A north-south trough from Madhya Pradesh to the Tamil Nadu coast across east Vidarbha, Andhra Pradesh, south interior Karnataka and Tamil Nadu indicates the line of wind dis-continuity has also formed in the Peninsula region.This is a pre monsoon formation, and is a fore-runner for the seasonal low to stretch its presence over central India.              
Indicator: +ve

Conclusion: There continues to be a doubt on the timely arrival of the Monsoon in the Bay branch. The Arabian Sea branch, may not be affected by the temporary "dis-organisation " in the equatorial winds at the equator. ( Provided they regroup fast as predicted). Rains have also tapered down a bit on the South-West coast, as required now. Arrival date should be around 1st. June for Kerala.
(This Monsoon chase is my personal view, and my personal analysis and deciphering is done as per my assumptions). 

1 comment:

anant said...

Intresting , if i remember correctly the cyclone formed in the Bay (Aila) took away lot of moisture and impeded monsoon flow, do you think that this time cyclone is a distant possibility and actually it will help organise monsoon flow.