972
WTNT42 KNHC 091442
TCDAT2
HURRICANE FRED DISCUSSION NUMBER 8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072009
1100 AM AST WED SEP 09 2009
FRED HAS CONTINUED TO RAPIDLY INTENSIFY THIS MORNING AND IS NOW A
MAJOR HURRICANE. SATELLITE IMAGES SHOW THAT THE EYE HAS BECOME
DISTINCT ON BOTH VISIBLE AND INFRARED CHANNELS AND REMAINS
EMBEDDED WITHIN A COLD CENTRAL DENSE OVERCAST. THE LATEST DVORAK
ESTIMATES FROM TAFB/SAB ARE 102 KT...WITH OBJECTIVE T-NUMBERS NEAR
115 KT. THE INITIAL INTENSITY IS RAISED TO 105 KT...MAKING FRED
THE SECOND MAJOR HURRICANE OF THE SEASON.
ADDITIONAL STRENGTHENING IS POSSIBLE TODAY BEFORE INCREASING SHEAR
AND SLIGHTLY COOLER WATERS CAUSE FRED TO WEAKEN TOMORROW.
THEREAFTER...THE HURRICANE WILL BE MOVING OVER MARGINAL SSTS COOLER
AND INTO A DRIER MID-LEVEL AIRMASS...WHICH SHOULD ENHANCE THE
WEAKENING EFFECTS OF THE EXPECTED STRONG SHEAR. THE LATEST NHC
FORECAST IS CLOSE TO A BLEND OF THE SHIPS MODEL AND THE PREVIOUS
FORECAST. THE GFDL AND HWRF MODELS...WHICH APPEAR TO BE LESS
SENSITIVE TO INCREASED SHEAR...DO NOT WEAKEN FRED NEARLY AS MUCH AS
THE OFFICIAL FORECAST AT DAYS 4 AND 5.
THE MOTION CONTINUES TO BEND GRADUALLY TO THE RIGHT AND IS NOW ABOUT
305/11. THERE IS NO CHANGE TO THE FORECAST REASONING AS MOST
GUIDANCE IS WELL-CLUSTERED ON A GRADUAL TURN TOWARD THE NORTH AND
NORTHEAST DUE TO A MID- TO UPPER-LEVEL TROUGH OVER THE CENTRAL
ATLANTIC. IN ABOUT 48 HOURS...ALL GUIDANCE SIGNIFICANTLY
DECELERATES FRED AS THE HURRICANE BECOMES CAUGHT IN LIGHT STEERING
CURRENTS. MOST OF THE GLOBAL MODELS REBUILD THE RIDGE TO THE NORTH
OF FRED BY THE END OF FORECAST PERIOD...WHICH WOULD CAUSE THE
CYCLONE TO MOVE MORE TO THE NORTHWEST. THE OFFICIAL FORECAST IS
SLIGHTLY EAST OF THE MODEL CONSENSUS INITIALLY...THEN ENDS UP
SOMEWHAT TO THE WEST IN THE ANTICIPATION THAT A WEAKER SYSTEM WOULD
TAKE A MORE WESTWARD PATH. THE TWO BIGGEST OUTLIERS TO THIS
FORECAST ARE THE GFDL AND HWRF...WHICH TAKE FRED FARTHER NORTH THAN
MOST OF THE OTHER MODELS...PROBABLY BECAUSE THEY KEEP IT AS A DEEP
CYCLONE FOR TOO LONG.
IT IS QUITE UNUSUAL TO HAVE SUCH A POWERFUL SYSTEM SO FAR EAST IN
THE BASIN AND FRED IS ONLY THE THIRD MAJOR HURRICANE NOTED EAST OF
35W IN THE TROPICAL ATLANTIC OCEAN...AND THE STRONGEST HURRICANE SO
FAR SOUTH AND EAST IN OUR DATA RECORD. THIS TYPE OF SYSTEM...
HOWEVER...WOULD HAVE BEEN VERY DIFFICULT TO ACCURATELY OBSERVE
BEFORE SATELLITE PICTURES BEGAN IN THE 1960S.
FORECAST POSITIONS AND MAX WINDS
INITIAL 09/1500Z 13.9N 32.4W 105 KT
12HR VT 10/0000Z 14.9N 33.5W 110 KT
24HR VT 10/1200Z 16.2N 34.3W 105 KT
36HR VT 11/0000Z 17.2N 34.7W 90 KT
48HR VT 11/1200Z 17.7N 34.6W 80 KT
72HR VT 12/1200Z 18.7N 34.0W 60 KT
96HR VT 13/1200Z 20.5N 34.2W 45 KT
120HR VT 14/1200Z 23.5N 36.0W 30 KT
FORECASTER BLAKE
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