Thursday, April 12, 2007

Monsoon Watch - 3

The low pressure that formed around the southern tip of India, suddenly weakened into an "upper air circulation"(UAC). Some models suggest that this UAC may shift north east and head into the Bay of Bengal.If the Bay temperatures rise,(still around 30°), this may get converted into a low.

But, on the positive side for the monsoon,a "wind discontinuity line" has established along a north-south alignment in the southern peninsula. It could evolve into a trough of low pressure.This north - south trough gets converted to an east - west trough, before the on-set of the monsoon.
The line of wind discontinuity today runs from the southern tip of india upto Nagpur.The eastern side has moist south easterlies,thus producing convective rains,and the western side has dry northerlies.Thus, thunderstorms develop along the line of wind discontinuity.This is a convential pre monsoon feature.

With the confirmed deflection of W.D.'s away from the northern regions now,the ground for further heating of large areas of the sub continent has been prepared.Within a few days,temperatures in Sindh (Pakistan),Gujarat,Rajasthan may go upto 44°-46°.

In the Southern Hemisphere, the cyclone activity has stopped since the first week of April. At the instant, the south easterlies down there are re-curving at around 5°s, and thus indicating that the ITCZ is around 5°s. While the south easterlies should to gain speed in about 15 days, the ICTZ can cross the equator around first week of May, that is per the normal date. Once the moves towards the north, monsoon lows are formed in the Bay and Arabian Sea branch.

As on today, the monsoon seems to be on schedule.


Anonymous said...

Today's - 15th April image showed lightning activity stretching from Bihar to North Konkan (around Mumbai) and even Southern Gujarat, what is causing this? Also the's forcast for Mumbai shows 30-60% probability of T'storms for Mumbai for 6-8 days ahead - what is the reason for this. Such a prolonged T'storm spell (if it were to occur) is surely unusual.


Rajesh said...

If you will see in my last blog,I had mentioned the formation of a trough of low (2nd.para).Now this has formed,and due to the excessive heat,covective t-clouds have formed along the trough line.
The clouding over Bihar is due to another weak circulation.
By the way ,where are you located,and please give me your email for direct exchanges.

North India heat on 24th From Navdeep Dahiya Maharashtra heat on 24th.. Graph courtesy Shri Hosalikar (RMC)