972
WTNT42 KNHC 112039
TCDAT2
TROPICAL STORM FRED DISCUSSION NUMBER 17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072009
500 PM AST FRI SEP 11 2009
THE CLOUD PATTERN HAS BEEN SIGNIFICANTLY DISRUPTED BY SHEAR AND
CONSISTS OF A SHAPELESS AREA OF CONVECTION. THE CENTER IS STILL
NEAR A CONCENTRATED AREA OF THUNDERSTORMS BUT MICROWAVE IMAGES...
ALTHOUGH SPARSE...CLEARLY SHOW THAT THE LOW-LEVEL CENTER IS BECOMING
INCREASINGLY DETACHED FROM THE CONVECTION. GIVEN THE SATELLITE
PRESENTATION...AND THE LATEST DVORAK T-NUMBERS...THE INITIAL
INTENSITY HAS BEEN LOWERED TO 60 KNOTS. SINCE THE SHEAR OVER FRED
IS NOT GOING TO RELAX...WEAKENING IS FORECAST AND FRED WILL
GRADUALLY FADE.
FRED IS EMBEDDED WITHIN VERY LIGHT STEERING CURRENTS...AND HAS BEEN
DRIFTING NORTHEASTWARD. BRAVO TO MOST OF THE TRACK MODELS...WHICH
REALLY ANTICIPATED THIS RARE MOTION FOR SUCH A LOW LATITUDE CYCLONE
LOCATED IN THE CLIMATOLOGICAL TRADE WIND BELT. LITTLE MOTION IS
ANTICIPATED FOR THE NEXT TWO DAYS WHILE THE STEERING CURRENTS ARE
LIGHT. THEREAFTER...THE GLOBAL MODELS DEVELOP A SUBTROPICAL RIDGE
TO THE NORTH...A PATTERN MORE COMMON FOR SEPTEMBER...PROVIDING A
WEST-NORTHWESTWARD STEERING TO WHATEVER IS LEFT OF FRED. THE
WESTWARD BEND AFTER THREE DAYS IS THE SOLUTION OF MOST OF THE
RELIABLE GUIDANCE AND IS REFLECTED IN THE OFFICIAL FORECAST.
FORECAST POSITIONS AND MAX WINDS
INITIAL 11/2100Z 18.1N 34.6W 60 KT
12HR VT 12/0600Z 18.2N 34.4W 55 KT
24HR VT 12/1800Z 18.4N 34.4W 45 KT
36HR VT 13/0600Z 18.8N 34.9W 35 KT
48HR VT 13/1800Z 19.5N 36.0W 30 KT
72HR VT 14/1800Z 21.0N 40.0W 25 KT...REMNANT LOW
96HR VT 15/1800Z 22.5N 45.0W 20 KT...REMNANT LOW
120HR VT 16/1800Z 24.0N 50.5W 20 KT...REMNANT LOW
FORECASTER AVILA
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