Hurricane ILEANA

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HURRICANE ILEANA DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP102006
200 PM PDT TUE AUG 22 2006
 
CONVENTIONAL SATELLITE IMAGERY ALONG WITH RECENT MICROWAVE DATA
INDICATE THAT ILEANA IS FORMING AN EYE...AND SATELLITE INTENSITY
ESTIMATES ARE NOW UNANIMOUSLY 65 KT FROM ALL THREE AGENCIES.
ACCORDINGLY...ILEANA IS UPGRADED TO A HURRICANE...THE 5TH OF THE
2006 SEASON...WITH AN INITIAL INTENSITY OF 65 KT.  ILEANA IS
EXPECTED TO BE OVER VERY WARM WATERS AND WITHIN A VERY WEAK
VERTICAL SHEAR ENVIRONMENT OVER THE NEXT 72 HOURS.
ADDITIONALLY...SEVERAL OF THE GLOBAL MODELS SHOW A LARGE
ANTICYCLONE IN THE UPPER LEVELS DEVELOPING OVER THE HURRICANE.  TO
FULLY TAKE ADVANTAGE OF THIS ENVIRONMENT...ILEANA NEEDS ONLY TO
CONSOLIDATE ITS INNER CORE...WHICH APPEARS UNDERWAY.  ALL OF THESE
FACTORS FAVOR ADDITIONAL STRENGTHENING AND THE OFFICIAL FORECAST
INDICATES ILEANA APPROACHING CATEGORY THREE INTENSITY WITHIN 48
HOURS...CONSISTENT WITH THE SHIPS AND FSU SUPERENSEMBLE MODELS.
BEYOND 72 HOURS...THINGS GET VERY COMPLICATED GIVEN THE UNCERTAINTY
IN THE FORECAST TRACK AND THEREFORE THE UNDERLYING SST.  THE
OFFICIAL FORECAST ASSUMES ILEANA WILL MOVE OVER PROGRESSIVELY
COOLER WATERS RESULTING IN STEADY WEAKENING.
 
ILEANA IS MOVING RIGHT ALONG THE PREVIOUS TRACK WITH AN ESTIMATED
INITIAL MOTION OF 300/14.  MODELS CONTINUE TO DIVERGE IN THEIR
SOLUTIONS...WITH THE PRIMARY DIFFERENCE BEING THE DEPTH AND
STRENGTH OF THE CYCLONE.  SINCE THE NOGAPS...GFS...AND GFS ENSEMBLE
MEAN DO NOT HAVE A REASONABLE REPRESENTATION OF THE VORTEX...THOSE
SOLUTIONS ARE DEEMED LESS LIKELY.  THE UKMET AND GFDL MODELS...
BECAUSE THEY DEPICT A STRONGER AND DEEPER VORTEX...APPEAR TO
PROVIDE BETTER SOLUTIONS DURING THE FIRST 2-3 DAYS UNTIL THE
CYCLONE APPROACHES COOLER WATERS.  THEREAFTER...THE UKMET STALLS
THE CYCLONE WHILE THE GFDL TURNS IT NORTHWARD UNDER THE INFLUENCE
OF A MIDDLE TO UPPER-LEVEL TROUGH WHICH DEVELOPS ALONG THE WEST
COAST OF THE UNITED STATES.  IT IS ASSUMED THAT THE CYCLONE WILL
NOT BE DEEP ENOUGH TO BE PICKED UP BY THIS TROUGH. INSTEAD...THE
OFFICIAL FORECAST SHOWS A CONTINUED NORTHWESTWARD MOTION...ALBEIT
SLOWER...ON DAYS 4 AND 5.  IT SHOULD BE NOTED THAT THERE IS GREATER
THAN USUAL UNCERTAINTY IN THE FORECASTS AT THESE LONGER RANGES.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/2100Z 15.8N 108.2W    65 KT
 12HR VT     23/0600Z 16.8N 109.5W    75 KT
 24HR VT     23/1800Z 18.2N 111.6W    85 KT
 36HR VT     24/0600Z 19.3N 113.6W    95 KT
 48HR VT     24/1800Z 20.3N 115.3W    95 KT
 72HR VT     25/1800Z 21.6N 117.4W    80 KT
 96HR VT     26/1800Z 23.0N 119.0W    60 KT
120HR VT     27/1800Z 24.0N 121.0W    45 KT
 
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FORECASTER RHOME
 
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