Tropical Storm OPHELIA

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TROPICAL STORM OPHELIA DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT WED SEP 07 2005
 
DATA FROM NOAA LAND-BASED DOPPLER RADARS AND A NOAA RECONNAISSANCE
AIRCRAFT INDICATE OPHELIA HAS BECOME SLIGHTLY BETTER ORGANIZED...
BUT IT STILL REMAINS A SHEARED TROPICAL CYCLONE. THE INTENSITY OF
35 KT IS BASED ON A BLEND OF SURFACE REPORTS OF 33 KT FROM DRIFTING
BUOY 41542...LOCATED JUST NORTHEAST OF THE CENTER...AND DOPPLER
RADAR VELOCITIES OF 36-44 KT BETWEEN 10000 FT AND 12000 FT. THE
HIGHEST RECON WIND REPORT HAS BEEN 42 KT IN THE NORTHWEST QUADRANT.
 
THE INITIAL MOTION IS 335/07...BASED ON THE LAST 3 RECON POSITIONS.
THE TRACK FORECAST IS ANYTHING BUT STRAIGHTFORWARD. THE MAJORITY OF
THE GLOBAL MODELS TAKE OPHELIA SLOWLY NORTHWESTWARD FOR 24 HOURS
AND THEN GRADUALLY TURN THE CYCLONE NORTHEAST AND EASTWARD...AND
MAKE A SMALL CLOCKWISE LOOP EAST OF FLORIDA BY DAY 5. ONLY THE
GFDL...SHALLOW AND MEDIUM BAM...AND ECMWF MODELS TAKE OPHELIA
WESTWARD ACROSS THE CENTRAL FLORIDA PENINSULA AND INTO THE EASTERN
GULF. HOWEVER...THEY DO SO ALMOST IMMEDIATELY AND ALSO AS A VERY
WEAK SYSTEM. GIVEN THAT OPHELIA IS ALREADY WELL EAST OF THOSE MODEL
FORECASTS...AND THAT 500 MB HEIGHTS HAVE BEEN RISING MORE QUICKLY
ALONG THE GULF COAST RATHER THAN FARTHER NORTH...SUGGESTS THAT THE
GFDL AND ECMWF MOELS ARE BUILDING TOO MUCH RIDGING TOO THE NORTH OF
OPHELIA. A WEAK SHORTWAVE TROUGH OVER THE CENTRAL U.S. IS EXPECTED
TO GRADUALLY SLIDE SOUTHEASTWARD AND ERODE THE EASTERN PORTION OF
THE RIDGE...WHICH SHOULD ALLOW FOR LIGHT NORTHWESTERLY MID-LEVEL
FLOW TO DEVELOP OVER THE SOUTHEAST U.S. AND PUSH OPHELIA EASTWARD
AWAY FROM FLORIDA BY 36-48 HOURS. THE FORECAST TRACK IS SIMILAR TO
BUT SLOWER THAN THE NHC MODEL CONSENSUS AND IS TO THE RIGHT OF THE
PREVIOUS FORECAST TRACK. HOWEVER...GIVEN THE UNCERTAINTY IN THE
LONGER TIME PERIODS...POSSIBLE LANDFALL ACROSS NORTHERN FLORIDA OR
GEORGIA DURING THE NEXT 5 DAYS CAN NOT BE RULED OUT AT THIS TIME.
 
OPHELIAS IS EXPECTED TO REMAIN UNDER LIGHT TO MODERATE SOUTHERLY
SHEAR FOR THE NEXT 2-3 DAYS...SO ONLY SLOW STRENGTHENING IS 
FORECAST. AFTER 72 HOURS...THE CYCLONE IS EXPECTED TO MOVE
UNDERNEATH A NARROW 200 MB RIDGE AXIZ WHILE REMAINING OVER 29C
SSTS...WHICH SHOULD ALLOW OPHELIA TO REACH HURRICANE STRENGTH.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      07/0900Z 28.3N  78.9W    35 KT
 12HR VT     07/1800Z 28.5N  79.4W    40 KT
 24HR VT     08/0600Z 28.8N  79.8W    45 KT
 36HR VT     08/1800Z 29.0N  80.1W    50 KT
 48HR VT     09/0600Z 29.4N  80.3W    55 KT
 72HR VT     10/0600Z 29.8N  80.3W    60 KT
 96HR VT     11/0600Z 30.1N  80.0W    65 KT
120HR VT     12/0600Z 30.0N  79.5W    70 KT
 
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