Tropical Storm SERGIO

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TROPICAL STORM SERGIO DISCUSSION NUMBER  24
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP212006
700 AM PST SUN NOV 19 2006
 
THE LOW-LEVEL CIRCULATION CENTER OF SERGIO REMAINS EXPOSED UNDER THE
INFLUENCE OF STRONG SOUTHWESTERLY SHEAR AND CONVECTION CURRENTLY IS
AROUND 75 N MI EAST OF THE CENTER.  DVORAK DATA T-NUMBERS BASED ON
SHEAR PATTERNS FROM 1200 UTC REMAIN AT T3.0 FROM BOTH TAFB AND
SAB.  HOWEVER...FIRST-LIGHT VISIBLE PICTURES INDICATE THE CONVECTION
HAS BECOME FURTHER DETACHED...SO THE INITIAL INTENSITY HAS BEEN
LOWERED TO 35 KT...WHICH STILL COULD BE A BIT GENEROUS.  LATEST
QUIKSCAT PASS...FROM 1254 UTC...INDICATED 30-40 KT WINDS OVER THE
EASTERN SEMICIRCLE SOME OF WHICH ARE PROBABLY OVERINFLATED DUE TO
RAIN CONTAMINATION.
 
THE INITIAL MOTION IS ESTIMATED TO BE 270/3.  THE LOW- TO MID-LEVEL
RIDGE TO THE NORTH OF THE CYCLONE IS STEERING THE CYCLONE ON A
GENERAL WESTWARD MOTION.  HOWEVER...THE STRONG UPPER-LEVEL
SOUTHWESTERLY WINDS ARE HAMPERING THE CYCLONE'S FORWARD MOTION.  AS
THE RIDGE MIGRATES EASTWARD...THE SHEAR IS EXPECTED TO CONTINUE TO
INCREASE AND THE CYCLONE SHOULD BE STEERED SLOWLY TO THE WEST UNTIL
DISSIPATION OCCURS.  THIS IS CONSISTENT WITH THE GFDL AND FSU
SUPERENSEMBLE SOLUTIONS...AS WELL AS THE PREVIOUS FORECAST.
 
AS THE SHEAR IS FORECAST TO INCREASE...THE CIRCULATION SHOULD BE
PULLED FURTHER AWAY FROM THE CONVECTION.  CONTINUED WEAKENING IS
ANTICIPATED...AND SERGIO IS EXPECTED TO BE A REMNANT LOW IN TWO
DAYS.  THIS REASONING FOLLOWS CLOSELY WITH INTENSITY GUIDANCE FROM
SHIPS...GFDL...AND FSSE.  HOWEVER...BASED UPON THE CURRENT SATELLITE
DEPICTION OF THE CYCLONE WEAKENING TO A REMNANT LOW COULD OCCUR
FASTER THAN INDICATED IN THE FORECAST.  

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/1500Z 15.3N 105.5W    35 KT
 12HR VT     20/0000Z 15.4N 105.8W    30 KT
 24HR VT     20/1200Z 15.6N 106.2W    30 KT
 36HR VT     21/0000Z 15.8N 107.2W    25 KT...DISSIPATING
 48HR VT     21/1200Z 16.0N 108.5W    20 KT...REMNANT LOW
 72HR VT     22/1200Z 16.0N 110.5W    20 KT...REMNANT LOW
 96HR VT     23/1200Z...DISSIPATED
 
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FORECASTER MAINELLI
 
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