ISABEL #49 - DISCUSSION

[AussieMark]

000
WTNT43 KNHC 180857
TCDAT3
HURRICANE ISABEL DISCUSSION NUMBER 49
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT THU SEP 18 2003

WSR-88D RADAR DATA FROM MOREHEAD CITY SHOWS WHAT LOOKS LIKE A
CLASSIC CONCENTRIC EYEWALL FORMATION...WITH A POORLY-DEFINED RING
OF CONVECTION NEAR THE CENTER AND A STRONGER RING 40-50 NM OUT.
EARLIER AIRCRAFT DATA INDICATES THAT THE STRONGEST WINDS ARE
ASSOCIATED WITH THE OUTER RING...AND THAT THERE IS NO WIND MAXIMUM
ASSOCIATED WITH THE INNER RING. THE LAST AIRCRAFT FIX SHOWED A
PRESSURE OF 957 MB...AND MAXIMUM FLIGHT LEVEL WINDS DURING THE
MISSION WERE 109 KT. THE INITIAL INTENSITY REMAINS 90 KT.

ISABEL IS MOVING 325-330 DEGREES AT ABOUT 12 KT. A GENERAL
NORTHWESTWARD MOTION SHOULD CONTINUE FOR ABOUT 24 HR BETWEEN THE
DEVELOPING MID/UPPER-LEVEL TROUGH OVER THE SOUTHEASTERN UNITED
STATES AND THE DEEP-LAYER RIDGE OVER THE NORTHWESTERN ATLANTIC.
AFTER THAT...ISABEL SHOULD TURN NORTHWARD IN RESPONSE TO THE LARGE
DEEP-LAYER TROUGH MOVING EASTWARD ACROSS THE NORTHERN UNITED
STATES. ALL DYNAMICAL GUIDANCE AGREES WITH THIS SCENARIO...AND THE
OFFICIAL FORECAST TRACK IS BASICALLY AN UPDATE OF THE PREVIOUS
PACKAGE.

LITTLE CHANGE IN STRENGTH IS FORECAST BEFORE LANDFALL...ALTHOUGH
THERE IS STILL A SLIGHT CHANCE OF SLIGHT STRENGTHENING. AFTER
LANDFALL...ISABEL SHOULD WEAKEN AND GRADUALLY BECOME EXTRATROPICAL.

A NEW AIRCRAFT SHOULD BE ARRIVING AT THE CENTER SHORTLY.

FORECASTER BEVEN

FORECAST POSITIONS AND MAX WINDS

INITIAL 18/0900Z 33.1N 74.7W 90 KT
12HR VT 18/1800Z 35.0N 76.4W 90 KT...INLAND
24HR VT 19/0600Z 37.9N 78.2W 60 KT...INLAND
36HR VT 19/1800Z 41.4N 78.5W 45 KT...BECOMING EXTRATROPICAL
48HR VT 20/0600Z 47.0N 78.0W 35 KT...INLAND EXTRATROPICAL
72HR VT 21/0600Z 59.5N 72.5W 30 KT...INLAND EXTRATROPICAL
96HR VT 22/0600Z...ABSORBED BY EXTRATROPICAL LOW