[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 300237
TCDAT5
TROPICAL STORM SHARY DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL202010
1100 PM AST FRI OCT 29 2010

DEEP CONVECTION HAS PERSISTED THIS EVENING AND HAS EXPANDED A BIT
OVER THE SOUTHEAST THROUGH NORTHEAST PORTION OF THE CYCLONE.
EARLIER REPORTS FROM AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT
WITHIN THIS PARTICULAR AREA WERE 73 KT AT FLIGHT LEVEL...AND 60 KT
BASED ON AN SFMR WIND ESTIMATION.  CONSEQUENTLY...THE INITIAL
INTENSITY IS HELD AT 60 KT FOR THIS ADVISORY.  SHARY IS MOVING
WITHIN A REGION OF INCREASING SOUTHERLY SHEAR...NOW 20-30 KT...AND
IS FORECAST TO INCREASE FURTHER THROUGH THE PERIOD.  THE SHEAR
ALONG WITH COOLER SEA SURFACE TEMPERATURES SHOULD INDUCE A
WEAKENING TREND DURING THE NEXT 24 HOURS.  SATELLITE IMAGERY
INDICATES THAT A BAROCLINIC SYSTEM IS RAPIDLY APPROACHING
BERMUDA...AND INTERACTION WITH SHARY SHOULD BEGIN LATER TONIGHT.
THE FSU CYCLONE PHASE EVOLUTION DIAGRAMS FOR THE GFS/UKMET/CMC
UNANIMOUSLY AGREE THAT SHARY WILL COMPLETE THE TRANSITION TO AN
EXTRATROPICAL LOW WITHIN 24 HOURS...AND THIS IS INDICATED IN THE
OFFICIAL FORECAST.

THE INITIAL MOTION IS ESTIMATED TO BE NORTHEASTWARD...050/18.  THIS
GENERAL MOTION IS EXPECTED TO CONTINUE WITHIN THE DEEP SOUTHWESTERLY
TROPOSPHERIC FLOW DURING THE NEXT 24 HOURS AS THE SYSTEM MAKES ITS
TRANSITION TO A NON-TROPICAL LOW.  THE LIFE EXPECTANCY OF
POST-TROPICAL SHARY SHOULD BE SHORT...AS ALL OF THE LARGE-SCALE
MODELS SUGGEST THAT THE CYCLONE WILL BECOME ABSORBED BY THE FRONTAL
ZONE IN 36 HOURS.  THE OFFICIAL FORECAST IS BASED ON A BLEND OF THE
GFS...ECMWF...AND THE UKMET...AND IS ADJUSTED TO THE RIGHT OF THE
PREVIOUS ADVISORY.


FORECAST POSITIONS AND MAX WINDS

INITIAL      30/0300Z 31.9N  63.3W    60 KT
 12HR VT     30/1200Z 34.5N  59.0W    50 KT
 24HR VT     31/0000Z 38.2N  51.7W    45 KT...POST-TROP/EXTRATROP
 36HR VT     31/1200Z...ABSORBED BY FRONT

$$
FORECASTER ROBERTS/BROWN

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