Tropical Cyclone BOB D1 Update 2 ( TS Thane)

METD WEATHER

AKSHAY DEORAS

SEVERE WEATHER FORECASTER

The anticipated storm of the year TS BOB D1 ( Thane) is robustly growing and in the past 12hrs has significantly grown as was expected. 

The IR-BD spectrum satellite imagery clearly depicts a fully exposed LLCC which was partial 12hrs ago. The LLCC ( Low Level Cyclonic 

Circulation Center) is backed by stronger winds (over 35kt as per NRL) to the East of LLCC which seems to be the aggressive developing side of the system. Also the Highest PW lies around the East of the system which is backing up the LLCC. 

"The cyclonic storm THANE over southeast Bay of Bengal moved northwestwards and lay centered at 1730 hrs IST of today, the 27^th December 2011 near latitude 12.5⁰N and longitude 86.5⁰E, about 650 km east-southeast of Chennai (Tamilnadu), 700 km northeast of Trincomalee (Srilanka) and 670 km west-northwest of Port Blair (Andaman & Nicobar island)"

 IMD QUOTES AT 1730 IST,27TH DEC 2011

The argument is not on the LLCC but is on the overall momentum of the system. In the past 12hrs, the low level convergence has decreased barely to 5kt as per CIMSS and the system is on the boundary of 28C SST and shall soon step in the 27C. Guidance indicates that the Vertical wind shears have temporarily relaxed as the system continues to mature amidst an excellent poleward outflow south of the tropical ridge ( high pressure area) which shall intensify more leading to a more West-North West bend in the path. 

Given the present microwave imagery,it appears that TS BOB D1 ( Thane) HAS CROSSED THE MID STAGE OF FINAL INTENSIFICATION ROUND. 

Considering the present estimates from CIMSS,GFS and the overall dynamics including the decreased lower convergence,lower SST and cool air dry inflow METD WEATHER ESTIMATES THE SYSTEM TO REACH THE PEAK IN NEXT 8 HOURS AND THEN START WEAKENING. 

FORECASTS ( VALID +12HRS FROM 1130PM IST,27TH DEC)

TS BOB D1 WILL REACH THE PEAK INTENSITY ON WED ( 28TH DEC 2011) MORNING PERIOD 

METD WEATHER ESTIMATES THE SYSTEM TO REACH THE CATEGORY 1 STATUS ( IF THE PRESENT MAX WIND OF 1 MIN SUSTAINED IS OVER 105KM/HR WHICH IS NOT KNOWN)

THE SYSTEM WILL WEAKEN FROM 12 NOON,28TH DEC 2011 AND PROGRESS TOWARDS AREAS AROUND CHENNAI ON 29TH DEC EVENING

IT SHALL BE A TROPICAL DEPRESSION DURING LANDFALL

CENTRAL INDIA MOISTURE INCURSION- 

THE MOISTURE ASSOCIATED WITH THE BOB D1 AFTER LANDFALL AT MID LEVELS SHALL MOVE TOWARDS THE CENTRAL INDIA CONSIDERING THE 12Z,GFS 27TH DEC 2011 RUNS. THE LOWER TO MID LEVEL WINDS UNDER THE INFLUENCE OF THE SYSTEM AROUND NGP SHALL BE SOUTH SOUTH-EAST

IF IT CONTINUES THEN THE CENTRAL PARTS OF INDIA WILL GET SOME RAINFALL ON NEW YEAR EVE ESPECIALLY 31ST DEC 2011 AND SOMETIME AROUND 1-2 JAN 2012 WHICH WILL DEPEND ON THE PATH.. 

Akshay Deoras
Severe Earth & Space Weather Forecaster,Astrophysics article writer.

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