Monday, May 13, 2013

Cyclone "Mahasen" - No sign of Northerly movement yet !

Latest analysis show that the system has moved N-W during past 6 hrs.
Present location is 12.8N , 85.7E.
From morning, the pressure and wind speed has remained the same.


JTWC warning and path projection at 8:30pm IST

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TROPICAL CYCLONE 01B (MAHASEN), LOCATED APPROXIMATELY 630 NM SOUTH-
SOUTHWEST OF KOLKATA, INDIA, HAS TRACKED NORTHWESTWARD AT 09 KNOTS 
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY 
(MSI) SHOWS A LARGE CENTRAL DENSE OVERCAST FEATURE WITH A PARTIALLY 
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC). A 131116Z SSMIS 37 GHZ 
MICROWAVE IMAGE SHOWS THE BULK OF THE DEEP CONVECTION IS SHEARED 
WEST OF THE LLCC WITH SOME SHALLOW FRAGMENTED CONVECTIVE BANDING TO 
THE NORTH. THE INITIAL POSITION IS BASED UPON THE MICROWAVE IMAGE 
WITH FAIR CONFIDENCE. THE INITIAL INTENSITY REMAINS ASSESSED AT 50 
KNOTS WHICH IS SLIGHTLY HIGHER THAN A DVORAK CURRENT INTENSITY 
ESTIMATE OF 45 KNOTS FROM PGTW DUE TO THE TIGHTLY WRAPPED STRUCTURE 
OF THE SYSTEM. UPPER LEVEL ANALYSIS INDICATES FAVORABLE WESTWARD 
OUTFLOW IS BEING OFFSET BY MODERATE (15-20 KNOTS) VERTICAL WIND 
SHEAR (VWS), WHICH IS EVIDENT IN THE PARTIALLY EXPOSED NATURE OF THE 
SYSTEM. TC 01B IS CURRENTLY IN A WEAK STEERING ENVIRONMENT AS THE 
SUBTROPICAL STEERING RIDGE EAST OF THE SYSTEM IS WEAKENING AND RE-
ORIENTING IN RESPONSE TO AN APPROACHING MIDLATITUDE SHORTWAVE 
TROUGH, WHICH IS CURRENTLY OVER NORTHEASTERN INDIA. TC 01B IS 
EXPECTED TO SLOWLY TRACK NORTH FOR THE NEXT DAY AS THE STEERING 
RIDGE REMAINS WEAK AND CONTINUES TO RE-ORIENT. AFTER TAU 24, THE 
SYSTEM IS EXPECTED TO ACCELERATE AND TRACK NORTHEAST AHEAD OF THE 
TROUGH. AS THE SYSTEM GAINS LATITUDE, GRADUAL INTENSIFICATION IS 
EXPECTED AS VWS RELAXES AND INCREASING POLEWARD OUTFLOW FROM THE 
STRONG WESTERLIES NORTH OF THE SYSTEM ALLOWS FOR A PEAK INTENSITY OF 
70 KNOTS AT TAU 72. AFTER TAU 72, TC 01B WILL BEGIN TO WEAKEN AS VWS 
INCREASES AND LAND INTERACTION ALLOWS FOR DISSIPATION OVER LAND AT 
TAU 120. DYNAMIC MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT AS 
NAVGEM HAS STARTED TO SHOW THE RECURVE SCENARIO, ALTHOUGH IT REMAINS 
THE WESTERN OUTLIER. ALTHOUGH THERE IS A GENERAL AGREEMENT IN THE 
RECURVE, MODELS CONTINUE TO VARY IN THE TIMING AND SPEED OF THE 
TURN. IN LIGHT OF THIS, THE JTWC FORECAST IS LAID CLOSE TO MULTI-
MODEL CONSENSUS WITH LOW CONFIDENCE DUE TO THE LARGE SPREAD IN 
SOLUTIONS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 131200Z IS 21 FEET.
All weather models other than NAVGEM model has predicted a Odisha coast landfall as Cyclone on 17-May.

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