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Hurricane DANIEL


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HURRICANE DANIEL DISCUSSION NUMBER  27
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP052006
800 AM PDT SUN JUL 23 2006
 
DANIEL REMAINS AN IMPRESSIVE CATEGORY FOUR HURRICANE IN SATELLITE
IMAGERY. DESPITE MOVING OVER SLIGHTLY COOLER WATERS....CLOUDS TOPS
HAVE COOLED ONCE AGAIN AND THE EYE HAS BECOME MORE DISTINCT. A
BLEND OF SUBJECTIVE SATELLITE INTENSITY ESTIMATES YIELDS AN 
AVERAGE OF 115 KT...WHILE UW-CIMSS THREE-HOURLY AVERAGE RAW ADT
ESTIMATES ARE T6.3 ABOUT 122 KT. THEREFORE...THE INITIAL INTENSITY
REMAINS 115 KT. 
    
EVEN THOUGH THE HURRICANE HAS BEEN FORECAST TO SOON SLOW DOWN...
DANIEL CONTINUES TO MOVE STEADILY WEST-NORTHWESTWARD AND THE
INITIAL MOTION IS ESTIMATED AT 285/12. THE CYCLONE CONTINUES 
TO BE STEERED BY A STRONG MID-TO-UPPER LEVEL RIDGE TO ITS
NORTH...WHICH MOST OF THE MODELS HAVE BEEN FORECASTING TO WEAKEN. 
UNCERTAINTIES IN THE FORECAST TRACK AFTER 72 HOURS EXIST
AS A RESULT OF A RATHER LARGE SPREAD IN THE DYNAMICAL MODEL TRACKS.
BOTH THE GFDL AND GFS SIGNIFICANTLY BREAK DOWN THE RIDGE IN THE NEXT
24-48 HOURS. HOWEVER...BOTH MODELS HAVE VASTLY DIFFERENT SOLUTIONS. 
THE GFS SLOWS THE SPEED OF DANIEL TO 5 KT IN 24 HOURS AND THEN 2 KT
OR LESS BETWEEN 36 AND 96 HOURS...WHILE THE GFDL TURNS DANIEL
NORTHWARD JUST WEST OF 140W.  IN CONTRAST...THE UKMET AND NOGAPS
KEEPS A FAIRLY STRONG RIDGE THROUGHOUT THE ENTIRE FORECAST PERIOD
WHICH KEEPS DANIEL ON A STEADY WEST-NORTHWESTWARD TRACK.  SINCE IT
DOES NOT APPEAR THAT THE RIDGE WILL WEAKEN AS MUCH AS THE GFS/GFDL
SOLUTIONS THE OFFICIAL FORECAST TRACK WILL MAINTAIN A GENERALLY
WEST-NORTHWESTWARD MOTION...ALTHOUGH A BIT SLOWER THAN THE CURRENT
SPEED.  THE OFFICIAL FORECAST IS SLOWER THAN THE UKMET BUT IS CLOSE
TO THE NOGAPS AND GFDL/UKMET/NOGAPS MODEL CONSENSUS.
 
DANIEL IS EXPECTED TO REMAIN OVER 25C SSTS FOR THE NEXT 48 HOURS...
AND THEN MOVE OVER ONLY SLIGHTLY COOLER WATER. VERTICAL SHEAR IS
FORECAST BY THE GFS-BASED SHIPS MODEL TO REMAIN LOW THROUGH 96
HOURS AND THEN INCREASE TO 15-20 KT FROM THE SOUTH-SOUTHWEST. AS A
RESULT...THE SHIPS MODEL WEAKENS DANIEL SIGNIFICANTLY AT DAYS 
4 AND 5. HOWEVER...THE LARGE SAMPLING RADIUS USED BY THE SHIPS MODEL
APPEARS TO BE RESULTING IN AN OVERESTIMATE OF THE SHEAR SINCE BOTH
IT AND THE OTHER GLOBAL MODELS INDICATE DANIEL IS FORECAST TO MOVE
INTO A LIGHT WIND REGIME THAT IS EXPECTED TO EXIST BETWEEN SEVERAL
SMALL UPPER LEVEL LOWS AROUND THE HAWAIIAN ISLANDS. LOWER SHEAR
CONDITIONS COMBINED WITH SSTS NEAR 25C MAY RESULT IN DANIEL NOT
WEAKENING AS MUCH AS CURRENTLY INDICATED IN THE OFFICIAL FORECAST
AND BY THE SHIPS MODEL.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/1500Z 14.9N 135.7W   115 KT
 12HR VT     24/0000Z 15.4N 137.3W   105 KT
 24HR VT     24/1200Z 15.9N 139.1W    95 KT
 36HR VT     25/0000Z 16.3N 140.4W    85 KT
 48HR VT     25/1200Z 16.8N 141.8W    75 KT
 72HR VT     26/1200Z 17.8N 144.0W    65 KT
 96HR VT     27/1200Z 19.0N 147.5W    55 KT
120HR VT     28/1200Z 20.0N 152.5W    45 KT
 
$$
FORECASTER BROWN/STEWART
 
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