Hurricane FRED

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HURRICANE FRED DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072009
500 PM AST WED SEP 09 2009
 
THE EYE OF FRED HAS BECOME LESS DISTINCT THIS AFTERNOON AS CIRRUS
CLOUDS HAVE OBSCURED THE CENTER.  HOWEVER...CONVECTION IN THE
EYEWALL REMAINS STRONG WITH AN OVERALL SATELLITE APPEARANCE
BEFITTING A MAJOR HURRICANE.  SATELLITE CLASSIFICATIONS ARE A
LITTLE LOWER THAN SIX HOURS AGO...AND THE INITIAL INTENSITY IS
REDUCED TO 100 KT.  FURTHER WEAKENING IS POSSIBLE LATER TONIGHT BUT
A MORE SIGNIFICANT WEAKENING IS EXPECTED BY LATE TOMORROW AS FRED
ENCOUNTERS INCREASING VERTICAL WIND SHEAR AND DECREASING WATER
TEMPERATURES.  THESE ENVIRONMENTAL CONDITIONS ONLY GET MORE HOSTILE
AFTER 48 HOURS AND THE SHIPS MODEL ALSO DIAGNOSES DRY MID-LEVEL AIR
NEAR FRED.  INTENSITY GUIDANCE IS COMING INTO BETTER AGREEMENT WITH
THE HWRF/GFDL NOW SHOWING A WEAKER SYSTEM THAN EARLIER MODEL RUNS
BY DAY 5.  THE OFFICIAL FORECAST IS REASONABLY CLOSE TO A BLEND OF
THE SHIPS/LGEM AND THE PREVIOUS FORECAST.  IT WOULD NOT BE
SURPRISING IF FRED DISSIPATED BEFORE THE END OF THE FORECAST
PERIOD.
 
THE INITIAL MOTION IS NOW 315/11.  FRED CONTINUES TO GRADUALLY GAIN
LATITUDE AS SUBTROPICAL RIDGING ERODES TO ITS NORTH. WHILE THERE IS
GENERAL AGREEMENT ON THE HURRICANE TURNING TOWARD THE NORTH AND
DECELERATING IN A DAY OR SO...THERE ARE A VARIETY OF SOLUTIONS
THEREAFTER.  AT ONE EXTREME...THE UKMET HAS FRED MISSING A MID- TO
UPPER-LEVEL TROUGH OVER THE CENTRAL ATLANTIC...CAUSING THE CYCLONE
TO STALL SOUTH OF 17N AND EVENTUALLY MOVE WESTWARD UNDER A NEW
RIDGE.  A DIFFERENT SOLUTION IS PROVIDED BY THE GFDL/HWRF/NOGAPS
MODELS...WHICH SHOW FRED BEING STEERED QUICKLY NORTHWARD BY THAT
TROUGH AND APPROACHING 30N BY THE END OF THE FORECAST.  AT THIS
POINT...THE OFFICIAL FORECAST WILL LEAN ON THE IDEA THAT THE
CYCLONE WOULD EVENTUALLY WEAKEN AND BE STEERED MORE BY THE
LOWER-LEVEL FLOW AT LONG-RANGE...LEADING TO A MORE WESTWARD TRACK
AT THAT TIME. THE OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS
FORECAST AND REMAINS TO THE SOUTHWEST OF THE MODEL CONSENSUS AT DAY
5.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      09/2100Z 14.8N  33.3W   100 KT
 12HR VT     10/0600Z 15.8N  34.0W    95 KT
 24HR VT     10/1800Z 17.0N  34.6W    90 KT
 36HR VT     11/0600Z 17.8N  34.7W    80 KT
 48HR VT     11/1800Z 18.3N  34.4W    65 KT
 72HR VT     12/1800Z 19.5N  33.5W    50 KT
 96HR VT     13/1800Z 21.5N  34.5W    40 KT
120HR VT     14/1800Z 23.5N  37.0W    25 KT
 
$$
FORECASTER BLAKE
 
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