Hurricane DARBY

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HURRICANE DARBY DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 PM PDT WED JUL 28 2004
 
DARBY RETAINS A WELL-DEFINED EYE AND DVORAK INTENSITY ESTIMATES ARE
A CONSENSUS 5.0...OR 90 KT.  DARBY WILL BE CROSSING THE 26C SST
ISOTHERM IN ABOUT 12 HOURS...SO A LITTLE MORE INTENSIFICATION IS
POSSIBLE TONIGHT BEFORE THE SYSTEM BEGINS TO DECAY.  THE SHIPS
MODEL TAKES DARBY DOWN FAST...DISSIPATING THE SYSTEM IN 96 HOURS
AFTER IT PASSES OVER 23-24C WATER.  THE GFDL HAS A SLOWER DECAY...
EVEN SHOWING A BIT OF A RECOVERY AT 5 DAYS AS SSTS SLOWLY INCREASE
AGAIN.  IF THE GLOBAL MODELS ARE RIGHT...HOWEVER...STRONG WESTERLY
SHEAR SHOULD PREVAIL BY THEN AND PRECLUDE ANY RESTRENGTHENING.  THE
OFFICIAL FORECAST CALLS FOR A DECAY RATE THAT ROUGHLY SPLITS THE
DIFFERENCE BETWEEN THE SHIPS AND GFDL AND IS SIMILAR TO THE
PREVIOUS ADVISORY.

THERE HAS BEEN NO CHANGE TO THE TRACK FORECAST PHILOSOPHY AND THE
OFFICIAL FORECAST LARGELY UPDATES THE PREVIOUS TRACK.  SUFFICIENT
RIDGING TO THE NORTH OF THE CYCLONE SHOULD KEEP THE PRESENT
MOTION...295/12...STEADY UNTIL DARBY WEAKENS AND TURNS A LITTLE TO
THE LEFT WITH A SHALLOW LAYER FLOW.  THE GFS...WHICH INITIALIZES
DARBY AS A 1010 MB LOW AND WEAKENS IT QUICKLY...REMAINS THE OUTLIER
ON THE LEFT SIDE OF THE GUIDANCE ENVELOPE.  THE NOGAPS ON THE OTHER
HAND KEEPS DARBY SEEMINGLY TOO STRONG AND TAKES IT NORTHWESTWARD
INTO A WEAKNESS IN THE SUBTROPICAL RIDGE.  THE OFFICIAL FORECAST IS
IN BEST AGREEMENT WITH THE UKMET AND MEDIUM BAM.

FORECASTER FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/0300Z 16.6N 125.8W    90 KT
 12HR VT     29/1200Z 17.3N 127.5W    90 KT
 24HR VT     30/0000Z 18.0N 129.6W    80 KT
 36HR VT     30/1200Z 18.6N 131.8W    70 KT
 48HR VT     31/0000Z 19.0N 134.0W    60 KT
 72HR VT     01/0000Z 19.5N 139.0W    45 KT
 96HR VT     02/0000Z 20.0N 144.0W    35 KT
120HR VT     03/0000Z 20.0N 149.0W    30 KT
 
 
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