The low-pressure area formed over the Bay of Bengal is sort of "blowing hot and blowing cold". From showing no signs of deepening on Wednesday, it suddenly became 99B on Thursday, raising hopes of becoming "well marked".(Sounds familiar, heard this before :))
In sympathy, the western trough off the coast suddenly shot into action, and precipitated heavy rains along the Konkan/Goa coast on Thursday (24th.), wiping out the fears of reducing rainfall there due to the "break Monsoon" scare. And, the monsoon axis, as if in obeyance, has retreated its threatening stand, by forming a core of 992 mb far away from the Indian land mass,deep into the Sindh desert. The correct place for the western end of a typical axis.
The low in the bay is likely to become ‘well marked' soon.That's the repeated expectation since the last 24hrs,but as and when it does, it should travel west into India, and merge into a W.D. approaching from the northwest, and set up rains over the Gangetic plains, and rain in some places in the North, bringing some respite from the severe heat.
But as estimated, the interiors of the peninsula region are relatively drier. Rainfall figures of interior Maharashtra and peninsula cities are still wanting, and rains are badly needed there. And may remain so for the next 2/3 days.
Mumbai has got more than its a fair share of drenching. With Colaba recieving 210 mms of rain in the last 24 hrs, ended Friday morning, the June total has leaped to 909 mms. Now thats a whopping 495 mms above the noraml, or +54%, for this time of the year. The all time high for June is 1280 mms.
But the all India average is -11%, a big improvement from last year, after the disastrous 54 per cent deficit recorded up to June 25 last season. The year 2009 had witnessed the worst drought in three decades.
The +ve regions are the areas where the monsoon has not yet arrived. Like Rajasthan, with+214%. But mainly due to the interaction of the remant of Phet with a W.D. over the region. -ve is in the East.
One of our readers has rightly commented today, that Mumbai is recieving very good rains in spite of no system or active MJO, either from the bay or the Arabian Sea. Defying forecasts, the off shore trough along the west coast, a permanent feature during the monsoon, has shown "its strenght" in the last 4 days and produced very good rainfall along the Konkan and specially off the Mumbai coast.
You see, the trough has been "going on and off" very frequently. It formed a embedded vortex, which suddenly disappeared, without crossing the coast. But still precipitated rains off the Mumbai area (see previous blog). Now today, its Northern end has abruptly moved North to the Saurashtra coast. While observing the trough. I had judged about 100 mms of rain for Mumbai Thursday/Friday, but Thursday itself brought 210mms in Colaba, but 120 mms in the suburbs.Sporadic and differentiating.Santa Cruz total till today is 643 mms !
Ahead,I see the rains lessening a bit in Mumbai during the weekend, only to pick up slightly from Monday.
Further Monsoon movement will depend on the behaviour of the low in the bay. Dont see much prospects of the low picking up till Monday.Hence, rainfall in the interiors of Maharashtra, Karnatak,and eastern plains of Northern India will be restricted. But rainfall can be expected, next 2 days,in Chattisgarh and Eastern M.P. due to the weak low persisting.
Do not see rains advancing much into Saurashtra too.