Hurricane ISABEL

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HURRICANE ISABEL DISCUSSION NUMBER  48
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT WED SEP 17 2003
 
ISABEL LACKS A WELL-DEFINED INNER CORE AND DEEP CONVECTION IS
MINIMAL AT THIS TIME. IN FACT...SATELLITE INTENSITY ESTIMATES
SUGGEST THAT MAXIMUM WINDS ARE ON THE ORDER OF 75 TO 80 KNOTS.
DATA FROM A RECONNAISSANCE PLANE INDICATE THAT MAXIMUM FLIGHT-LEVEL
WINDS ARE ABOUT 100 KNOTS SO FAR ON THIS MISSION...WITH THE CENTRAL
PRESSURE UNCHANGED.  ASSUMING THAT THE RECONNAISSANCE PLANE HAS NOT
SAMPLED THE ENTIRE CIRCULATION...THE INITIAL INTENSITY IS KEPT
GENEROUSLY AT 90 KNOTS.  IF THE PLANE DOES NOT FIND HIGHER WINDS
SOON...IT MAY BE NECESSARY TO DECREASE THE INTENSITY IN THE NEXT
ADVISORY. ON THE OTHER HAND...SINCE THE OUTFLOW IS EXCELLENT AND
THE HURRICANE HAS ABOUT 12 HOURS OVER WARM WATERS...THERE IS STILL
A CHANCE THAT SOME RE-INTENSIFICATION MAY OCCUR JUST BEFORE
LANDFALL.
 
SATELLITE AND RECONNAISSANCE FIXES INDICATE THAT ISABEL IS MOVING 
ABOUT 330 DEGREES AT 11 KNOTS. THE STEERING PATTERN CALLS FOR
A GENERAL NORTH-NORTHWESTWARD TO NORTHWESTWARD TRACK AS THE HIGH
BUILDS TO THE NORTHEAST OF THE TROPICAL CYCLONE. THIS MOTION WOULD
BRING THE CENTER OF THE HURRICANE TO THE COAST OF NORTH CAROLINA
DURING THE DAY ON THURSDAY.  THERE IS CONFIDENCE IN THE OFFICIAL
FORECAST SINCE THE MORE RELIABLE TRACK MODELS ARE HIGHLY CLUSTERED
WITHIN 40 NAUTICAL MILES NEAR LANDFALL.  HOWEVER...ONE SHOULD NOT
FOCUS ON A PRECISE LANDFALL POINT SINCE ISABEL IS A LARGE HURRICANE
WITH DAMAGING WINDS EXTENDING WELL AWAY FROM THE CENTER.
 
ONCE ISABEL MOVES INLAND...IT SHOULD GRADUALLY BECOME EXTRATROPICAL
AND THEN BECOME ABSORBED BY A LARGER CYCLONE IN 3 OR 4 DAYS.
 
FORECASTER AVILA/PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/0300Z 31.9N  73.9W    90 KT
 12HR VT     18/1200Z 33.7N  75.6W    95 KT
 24HR VT     19/0000Z 36.5N  77.5W    65 KT...INLAND
 36HR VT     19/1200Z 39.5N  78.5W    50 KT...INLAND
 48HR VT     20/0000Z 43.0N  77.5W    40 KT...BECOMING EXTRATROPICAL
 72HR VT     21/0000Z 57.0N  73.5W    30 KT...EXTRATROPICAL
 96HR VT     22/0000Z...ABSORBED BY EXTRATROPICAL LOW
 
 
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