Tropical Storm SERGIO
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TROPICAL STORM SERGIO DISCUSSION NUMBER 17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP212006
100 PM PST FRI NOV 17 2006
SERGIO'S LOW-LEVEL CENTER HAS SEPARATED FROM THE DEEP
CONVECTION...WHICH HAS BEEN DISLOCATED TO THE NORTHEAST BY
SOUTHWESTERLY UPPER-LEVEL WINDS. A SLIGHT ADJUSTMENT OF THE
CYCLONE'S POSITION TO THE SOUTH WAS MADE ONCE VISIBLE SATELLITE
IMAGERY WAS AVAILABLE THIS MORNING. SERGIO'S CURRENT MOTION IS A
SLOW DRIFT TO THE NORTH. THE CYCLONE SHOULD TURN TOWARD THE
NORTHWEST AND ACCELERATE SOMEWHAT AS IT BECOMES STEERED BY THE
LOWER TROPOSPHERIC FLOW ON THE SOUTH SIDE OF THE RIDGE. THE
FORECAST TRACK GOES WITH THE CONSENSUS OF THE DYNAMICAL
MODELS...WITH THE EXCEPTION OF THE GFS MODEL IN THE FIRST 24
HOURS...WHICH HAS AN UNREALISTIC INITIAL MOTION TO THE WEST.
INTENSITY ESTIMATES OF ABOUT 40 KT WERE PROVIDED BY THE CIRA AND
CIMSS TECHNIQUES FROM A 1227 UTC AMSU PASS. HOWEVER...A BLEND OF
THE DVORAK CI AND DATA-T NUMBERS FROM TAFB...SAB...AND AFGW SUGGEST
AN INTENSITY OF 45 TO 50 KT AT 18 UTC. GIVEN THE CONTINUED
DETERIORATION OF THE CONVECTION NEAR THE CENTER AND THE AMSU
VALUES...THE ANALYZED INTENSITY IS SET AT 40 KT. DESPITE RATHER
WARM SSTS...THE IMPACT OF WIND SHEAR AND A STABLE ATMOSPHERE SHOULD
CONTINUE TO CAUSE SERGIO TO WEAKEN. THE FORECAST INTENSITY IS
CLOSE TO SHIPS AND THE FSU SUPER-ENSEMBLE...BUT IS SUBSTANTIALLY
BELOW THE GFDL MODEL WHICH...FOR SOME REASON...CONTINUES TO PREDICT
SERGIO TO BE A HURRICANE DURING THE NEXT TWO DAYS.
FORECAST POSITIONS AND MAX WINDS
INITIAL 17/2100Z 14.0N 102.6W 40 KT
12HR VT 18/0600Z 14.3N 102.7W 35 KT
24HR VT 18/1800Z 14.8N 102.9W 30 KT
36HR VT 19/0600Z 15.6N 103.6W 30 KT
48HR VT 19/1800Z 16.3N 104.2W 25 KT
72HR VT 20/1800Z 17.5N 107.0W 20 KT...REMNANT LOW
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FORECASTER AVILA/LANDSEA
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