Hurricane SHARY

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HURRICANE SHARY DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL202010
500 AM AST SAT OCT 30 2010
 
SHARY POSES A BIT OF A CONUNDRUM THIS MORNING.  THE LATEST SATELLITE
IMAGES SHOW THAT DEEP CONVECTION HAS CONTINUED TO GROW AND BECOME
MORE SYMMETRIC NEAR THE CENTER.  IN ADDITION...TRMM PASSES FROM
OVERNIGHT INDICATED THE DEVELOPMENT OF A SMALL EYE FEATURE IN THE
37-GHZ CHANNEL.  WHILE DVORAK T-NUMBERS ARE HIGHER THAN EARLIER
...THEY ARE FAR FROM SUPPORTING HURRICANE INTENSITY...ALTHOUGH
THESE SATELLITE ESTIMATES ARE CLEARLY NOT HANDLING THIS SYSTEM WELL. 
THE DEEPENING OF CONVECTION AND THE EYE FEATURE IN MICROWAVE IMAGERY
SUGGEST A FURTHER ORGANIZATION OF SHARY AND AT LEAST A NOMINAL
INCREASE IN WIND SPEED FROM THE 60 KT OBSERVED FROM THE AIRCRAFT. 
NORMALLY A 5-KT WIND ADJUSTMENT WOULD NOT REQUIRE THIS MUCH
DISCUSSION...BUT A CHANGE IN STATUS DOES COMPLICATE MATTERS.  IT IS
HARD TO DISCOUNT THE LARGE CONVECTIVE INCREASE AND THE SIGNIFICANT
IMPROVEMENT ON MICROWAVE IMAGES SINCE THE AIRCRAFT DEPARTED...THUS
THE INITIAL WINDS ARE NUDGED UPWARD TO 65 KT.  THIS IS A GOOD CASE
OF A SMALL HURRICANE THAT WAS VERY UNLIKELY TO BE OBSERVED BEFORE
THE RECENT ERA WHEN MICROWAVE SATELLITE IMAGERY WAS AVAILABLE. 

THE TRMM PASSES AND GEOSTATIONARY SATELLITE IMAGERY INDICATE THAT
SHARY HAS ACCELERATED CONSIDERABLY AND IS NOW SPEEDING
NORTHEASTWARD AT ABOUT 30 KT. THIS GENERAL TRACK IS EXPECTED TO
CONTINUE WHILE THE SYSTEM REMAINS ENTRENCHED IN SOUTHWESTERLY
MID-LATITUDE FLOW. A COLD FRONT RAPIDLY APPROACHING SHARY IS
EXPECTED TO CAUSE THE HURRICANE TO BECOME AN EXTRATROPICAL LOW
WITHIN 12 TO 24 HOURS BEFORE ABSORBING THE CYCLONE BY 36 HOURS. THE
GLOBAL MODELS ARE IN GOOD AGREEMENT ON THIS TRANSITION...AND THE
NEW FORECAST IS ADJUSTED TO THE RIGHT TO ACCOUNT FOR THE INITIAL
MOTION AND THE LATEST TRACK GUIDANCE. SHARY SHOULD BEGIN TO WEAKEN
SOON DUE TO INCREASING SHEAR AS IT MOVES OVER WATERS COOLER THAN
76F. THE INTENSITY FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS
ONE AFTER ACCOUNTING FOR THE SLIGHTLY HIGHER INITIAL WINDS. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      30/0900Z 33.6N  59.4W    65 KT
 12HR VT     30/1800Z 35.7N  54.6W    55 KT
 24HR VT     31/0600Z 38.5N  48.0W    45 KT...POST-TROP/EXTRATROP
 36HR VT     31/1800Z...ABSORBED BY A COLD FRONT
 
$$
FORECASTER BLAKE
 
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