Tuesday, June 30, 2009

The last 8 days has suddenly made all the difference and changed the total weather scenario, in the Indian region. The Monsoon, has moved, or jumped, northwestward by covering the states of Mah, Gujarat, Chattisgarh, M.P .Bihar and U.P. Delhi and parts of Punjab within with the last week. Thus, the northern limit of the Monsoon has achieved near normal levels after having lagged well behind in time and place by almost 15-20 days.

But now, onset/advance needs to be converted into normal rainfall, and as Jim from Accuweather puts it " for the details of atmospheric behavior under the setting of Monsoon are critical."

The June rain totals in almost all regions are below normal, that too to a large extent in regions of Mah, Karnatak to name a few. Details of the quatum of rain and deficit will be put up on this blog in a few days after the release of the details.
Now, this is predominantly due to be the lack depressions, the last was Tropical Cyclone Aila in the bay, and one depression in the Arabian Sea, fizzling out in 1 day over Gujarat.
After moving into Delhi today, mainly due to the Upper Air Circulation over the U.P. region, the monsoon may slow down for a few days. This can be due to the upper Air Circulation fizzling out due to lack of sufficient support from the bay.

And no "low" is forecasted yet in the bay, not till the 5th. of July .at least.
Rains may yet be subdued again in the states of Mah. Gujarat, M.P. Karnataka and the central/northwest regions of India. May not be a "break monsoon", but surely the easterly winds needed to bring in the bay moisture into central India will be missing till the 5th./6th.
But W.Bengal and the north-east may continue to recieve moderate rains, at times heavy, as the northern bay will be springing up a low in the next 5/6 days, and the moisture inflow into the W.B. coast may continue.

Normally, depressions deliver widespread rains in the main heartland of India. this year, the late onset and the absence of rain-making systems from the bay, is the reason for the deficit.
For the next 5 days, there is no indication of is any depressions.


2 comments:

Anonymous said...

I was checking the wind directions over Mumbai and what surprised me was that the wind direction changes from WSW to SW to E to SE etc., shouldn't the wind direction during SW Monsoon be from West or South West?

rajesh said...

I too observed the winds changing in Mumbai, from SE to E and sometimes due S. I cannot give an expert's comment on this. But I feel this is di=ue to the various small "vortex" that form in the off shore trough off Mumbai ,or Konkan coast. A vortex is something like a mini low pressure area. When this is formed off the north Konkan coast, the wins rotate, in a small region in the anti-clockwise cirection. Hence the changes we see sometimes, till the vortex vanishes.

I did not get your name as you had put in Anonymous. Can you please give your ID ?