Monday, November 25, 2013


Akshay Deoras
Severe Weather Forecaster,

Today afternoon, Tropical Storm LEHAR intensified to a Category 1 Cyclone as its max sustained winds reached 65 Kt and as of this post continue to be at 65Kt as the cyclone tracked west-northwest at around 07Kt (13km/hr) in the Bay of Bengal about 965km SE of Vizag,1100km east-south east of Machilipatnam,1050km east - south east of Kakinada,Andhra Pradesh and having tracked 200km from Port Blair after bringing heavy rains and winds in the Andaman and Nicobar Islands. However I am personally not convinced with the latest image of the system and some more observations, lets have a look here

Dry Air-

Like mentioned in yesterday's blog post, the amount of dry air entering the Bay of Bengal from East/North East India is increasing every hour as Cyclone LEHAR continues to act like a magnet doing this job. A 24hr comparison of the CIMSS Total Precipitable Water (TPW)clearly shows an increase in the spread of dry air which even now seems to be wrapping around the system in its northern periphery.

The topmost image shows TPW as of yesterday and the below image shows the latest precipitable water. One can see that blue,green region has moved further down (southward) as the Cyclone LEHAR presently at 12.5N,91.0E continues to move NW. Possibly the dry air is interacting with the outer rainbands- Northern and North-Western rainbands of LEHAR as can be possibly inferred from this latest IR-NHC imagery via CIMSS

The 1330UTC obtained NHC enhancement image shows a more or less oval structure of the CDO (Central Dense Overcast) feature which continues to obscure the LLCC. An animation of the IR imagery shows the centre is losing the convergence. It also indicated a possible exposed LLCC (although for a short time) and that the convection is possibly re-organising around a new centre marked by a very favoured wind field as can be seen in this image

The above IR BD image has contours of lower air convergence imposed on it. An increasingly favourable 30Kt region is developing coupled by an excellent poleward flow of 40Kt peak.
SST continues to be very favourable, in the 29C range which is overpowering the moderate 20kt wind shear in the region.

An analysis of all indicates that dry air has likely collided with the outer northern rainbands of Cyclone LEHAR and the convection is re-organising around a new centre and the system is overall maintaining its intensity. Over the next 12hrs, Cyclone LEHAR shall intensify gradually although I don't expect a Rapid Intensification yet considering the fact that wind shear are forecasted to remain moderate all the time in LEHAR's journey. Dry air wrapping shall be a factor to watch out and hence still I don't expect it to intensify beyond Category 2 which shall happen later tomorrow,26th Nov.

Given the fact that dry air interaction will act as a barrier and the SST will be decreasing beyond  36hrs from now ( morning of 27th Nov 2013), LEHAR shall make a landfall as a Category 2 cyclone close to Kakinada,Andhra Pradesh on the morning of Thursday,28th Nov 2013. The state of sea in the Bay of Bengal shall remain ROUGH in this period and hence fishermen shouldn't venture out in the sea till Friday,29th Nov 2013.

More details are awaited like potential damage to Andhra Pradesh coast which will enable to put the graphic map so STAY TUNED!!!

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