Hurricane ISABEL

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HURRICANE ISABEL DISCUSSION NUMBER  34
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SUN SEP 14 2003
 
SATELLITE IMAGERY SUGGESTS THAT ISABEL HAS WEAKENED DURING THE PAST
6 HOURS OR SO. EYEWALL CLOUD TOPS HAVE WARMED TO ABOVE -70C AND THE
THREE SATELLITE AGENCIES HAVE COME IN WITH A CONSENSUS INTENSITY
ESTIMATE OF T6.5...OR 127 KT. THE EYE REMAINS VERY DISTINCT AND
CIRCULAR...ALBEIT WITH AN UNUSUALLY LARGE 40 NMI DIAMETER. THE
INTENSITY HAS ONLY BEEN DECREASED SLIGHTLY DOWN TO 135 KT SINCE THE
EYE HAS BECOME EMBEDDED DIRECTLY IN THE CENTER OF THE CENTRAL DEEP
CONVECTION. SUCH PERFECT SYMMETRY OFTENTIMES INDICATES A CYCLONE
STRONGER THAN SATELLITE THE ESTIMATES...WHICH WAS THE CASE
YESTERDAY. RECON WILL IS SCHEDULED TO INVESTIGATE THE HURRICANE
THIS AFTERNOON.

THE INITIAL MOTION ESTIMATE IS 290/10. THERE IS NO SIGNIFICANT
CHANGE TO PREVIOUS FORECAST TRACK OR REASONING. SATELLITE FIX
POSITIONS HAVE BEEN COMING IN ON TOP OF THE PREVIOUS FORECAST TRACK
AND THE LATEST 06Z NHC MODEL GUIDANCE IS ALSO NOW STRONGLY
CONVERGENT ABOUT THE PREVIOUS FORECAST TRACK. THERE WAS A SLIGHT
WESTWARD SHIFT TO THE MODEL CONSENSUS...BUT THERE IS NOW MUCH LESS
DIVERGENCE AMONG THE GLOBAL AND REGIONAL MODELS THROUGHOUT THE
FORECAST PERIOD. UNFORTUNATELY...THE MODELS ARE NOW IN EXCELLENT
AGREEMENT WITH ISABEL MAKING LANDFALL ALONG THE CENTRAL U.S. EAST
COAST IN ABOUT 4 DAYS. THERE IS STILL UNCERTAINTY ON WHERE THE
EXACT LANDFALL COULD OCCUR SINCE THE DEVELOPING CENTRAL U.S. TROUGH
COULD DEEPEN AND DIG SOUTHWARD MORE THAN IS FORECAST BY THE GLOBAL
MODELS...WHICH COULD LEAD A MORE NORTHWARD MOTION AND LANDFALL
FARTHER UP THE EAST COAST THAN WHAT IS CURRENTLY FORECAST.
UNFORTUNATELY...ALL OF THE MODEL GUIDANCE AGREE ON A LARGE AND
STRONG NORTH-SOUTH ORIENTED RIDGE REMAINING EAST OF ISABEL...WHICH
SHOULD PREVENT THE POWERFUL HURRICANE FROM RECURVING OUT TO SEA.
LANDFALL ALONG THE U.S MID-ATLANTIC COAST SOMEWHERE BETWEEN NORTH
CAROLINA AND NEW JERSEY BETWEEN 4 OR 5 DAYS IS APPEARING MORE AND
MORE LIKELY.

ONLY MINOR FLUCTUATIONS IN INTENSITY ARE EXPECTED FOR THE NEXT 3
DAYS AS ISABEL IS FORECAST TO MOVE OVER SIGHTLY WARMER WATER AND
REMAIN IN A FAVORABLE DOUBLE-OUTFLOW PATTERN. HOWEVER...BY 96
HOURS...ISABEL IS EXPECTED TO BE ACCELERATING NORTH-NORTHWESTWARD
UNDER INCREASING SOUTHERLY UPPER-LEVEL FLOW. HOWEVER...ALL OF THE
MODELS ARE IN GOOD AGREEMENT ON THE CENTRAL CORE OF ISABEL
REMAINING EAST OF THE STRONG JETSTREAM AND UNDER 20-25 KT 200 MB
WIND. THIS WOULD TEND TO KEEP ISABEL STRONGER THAN WHAT THE SHIPS
INTENSITY MODEL IS INDICATING...ESPECIALLY SINCE ISABEL WILL BE
MOVING OVER THE WARM GULFSTREAM SOUTH OF THE NORTH CAROLINA OUTER
BANKS AT THAT TIME. THEREFORE...LITTLE OR NO SIGNIFICANT WEAKENING
IS EXPECTED TO OCCUR UNTIL AFTER LANDFALL OCCURS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/1500Z 23.7N  66.3W   135 KT
 12HR VT     15/0000Z 24.2N  67.9W   135 KT
 24HR VT     15/1200Z 25.2N  69.6W   135 KT
 36HR VT     16/0000Z 26.1N  70.6W   130 KT
 48HR VT     16/1200Z 27.2N  71.6W   125 KT
 72HR VT     17/1200Z 30.0N  73.2W   120 KT
 96HR VT     18/1200Z 34.5N  75.5W   110 KT...NEAR NORTH CAROLINA
120HR VT     19/1200Z 41.0N  77.5W    70 KT...INLAND
 
 
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