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SUBTROPICAL STORM GUSTAV DISCUSSION NUMBER   6
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT MON SEP 09 2002

VISIBLE IMAGERY INDICATES THAT MULTIPLE LOW-CLOUD SWIRLS ARE
ROTATING AROUND THE CENTER OF GUSTAV THIS AFTERNOON...WITH THE
MEAN CENTER CURRENTLY ON THE EDGE OF RE-DEVELOPING DEEP CONVECTION.
REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER INDICATE THAT
THE RADIUS OF MAXIMUM WINDS CONTINUES TO BE 75-100 N MI WITH
LITTLE OR NO EVIDENCE OF A WARM CORE.  THE MAXIMUM FLIGHT-LEVEL
WINDS DURING THE PAST 6 HR WERE 53 KT IN THE SOUTHEASTERN QUADRANT.
REPORTS FROM NOAA BUOY 41002 INDICATE THE CENTRAL PRESSURE HAS 
DROPPED TO NEAR 999 MB.  BASED ON ALL THE ABOVE...GUSTAV REMAINS
A 40 KT SUBTROPICAL STORM.
 
USING THE MEAN CENTER OF THE MULTIPLE LOW CLOUD SWIRLS GIVES AN
INITIAL MOTION OF 295/8.  THERE IS LITTLE CHANGE TO THE TRACK
FORECAST OR FORECAST PHILOSOPHY FROM THE PREVIOUS ADVISORY.  A
DEVELOPING DEEP-LAYER TROUGH OVER THE THE NORTHEASTERN U. S.
AND CANADIAN MARITIMES SHOULD BREAK DOWN THE RIDGE CURRENTLY
STEERING GUSTAV WEST-NORTHWESTWARD.  THIS WILL ALLOW THE CYCLONE
TO RECURVE TO THE EAST-NORTHEAST OR NORTHEAST.  AS EVEN THE ETA
MODEL IS NOW TRENDING TOWARD A RECURVATURE SOLUTION...THE ONLY
QUESTION IS WHEN WILL THE TURN OCCUR.  THE FORECAST TRACK GOES
WITH THE SCENARIO THAT THE RECURVATURE WILL BEGIN IN 12-24 HR WITH
THE CENTER PASSING JUST SOUTHEAST OF THE OUTER BANKS IN AGREEMENT
WITH MOS OF THE GUIDANCE.  HOWEVER...ANY DEVIATION TO THE LEFT OF
THE FORECAST TRACK COULD BRING THE CENTER ONSHORE ALONG THE NORTH
CAROLINA COAST.
 
THE CONVECTION HAS RE-ORGANIZED DURING THE AFTERNOON INTO A
CURVED BAND...AND THIS ALONG WITH THE CENTRAL PRESSURE FALL
SUGGESTS THAT A SLOW AND UNSTEADY DEVELOPMENT IS OCCURRING.
THE EASTERLY SHEAR SEEN EARLIER APPEARS TO BE SLOWLY DECREASING
AS FORECAST...AND THIS SHOULD ALLOW FOR SOME DEVELOPMENT OVER
THE NEXT 24-36 HR AS THE CENTER APPROACHES THE COAST.  AFTER THAT
TIME...THE DEVELOPING TROUGH WILL LIKELY INCREASE BOTH THE DYNAMIC
FORCING AND THE SHEAR ON GUSTAV.  THE INTENSITY FORECAST GOES WITH
THE SCENARIO THAT THE FORCING WILL WIN OUT OVER THE SHEAR UNTIL
THE CYCLONE BECOMES EXTRATROPICAL...AND THUS CALLS FOR SOME 
STRENGTHENING THROUGH 48 HR.

EVEN IF GUSTAV DOES NOT MAKE LANDFALL...IT IS FORECAST TO COME
CLOSE ENOUGH TO THE U. S. COAST TO SPREAD TROPICAL STORM WINDS
AND HEAVY RAINS ONSHORE.  ANY DEVIATION TO THE LEFT OF THE FORECAST
TRACK WOULD REQUIRE THE WARNINGS TO BE EXTENDED WESTWARD ALONG THE
COASTS OF NORTH AND SOUTH CAROLINA.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     09/2100Z 32.2N  74.8W    40 KTS
12HR VT     10/0600Z 32.9N  75.7W    45 KTS
24HR VT     10/1800Z 34.4N  75.7W    50 KTS
36HR VT     11/0600Z 35.5N  74.5W    55 KTS
48HR VT     11/1800Z 37.0N  71.0W    60 KTS
72HR VT     12/1800Z 42.5N  59.0W    55 KTS...EXTRATROPICAL
 
 
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