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SUBTROPICAL STORM GUSTAV DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT MON SEP 09 2002
 
THE AIRCRAFT FIX CENTER POSITION AT 00Z IS ABOUT 75 N MI SOUTHWEST
OF THE SATELLITE POSITIONS.  I AM FAVORING THE AIRCRAFT WHICH IS
SOMEWHAT SUPPORTED BY WILMINGTON AND MOOREHEAD CITY RADAR.  THIS
GIVES AN INITIAL MOTION OF 285/10 WHILE THE SATELLITE POSITIONS
GIVES A 310 DEGREE HEADING.  IN EITHER CASE...THE MODELS UNANIMOUSLY
TURN THE STORM NORTHWARD RIGHT AWAY AND NORTHEASTWARD BY 24 HOURS
AND SO DO I.  THE LARGE SCALE SCENARIO REMAINS THE SAME WITH A DEEP
TROUGH PICKING UP THE STORM IN 12 HOURS AND ACCELERATING IT
NORTHEASTWARD.
 
AN AIRCRAFT WIND OF 55 KNOTS AT 1500 FT TO THE SOUTHWEST OF THE
CENTER ALONG WITH 996 MB CENTRAL PRESSURE IS THE BASIS FOR
INCREASING THE WIND TO 45 KNOT.  STRENGTHENING TO 60 KNOTS IN 36
HOURS IS BASED ON A COMPROMISE BETWEEN THE AVIATION MODEL AND THE
MUCH MORE AGGRESSIVE SHIPS MODEL WHICH TREATS GUSTAV AS A TROPICAL
SYSTEM... WHICH IT IS NOT.  THE ONBOARD METEOROLOGIST FROM THE
GULFSTREAM 4 AIRCRAFT REPORTS THAT THE CIRCULATION EXTENDS UP TO 200
MB...THIS IS NOT TROPICAL.
 
THE 34-KNOT WIND SPEED RADII IN THE NORTHWEST QUADRANT IS ESTIMATED
AT 85 N MI BASED ON AIRCRAFT DATA AND A HURRICANE RESEARCH DIVISION
SURFACE WIND FIELD ANALYSIS.  THIS...ALONG WITH THE 24 HOUR FORECAST
POSITION REQUIRES CHANGING THE WATCH TO A WARNING FOR PORTIONS OF
VIRGINIA AND SOUTHERN CHESAPEAKE BAY.
 
FORECASTER LAWRENCE
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     10/0300Z 32.5N  75.9W    45 KTS
12HR VT     10/1200Z 33.5N  76.6W    50 KTS
24HR VT     11/0000Z 35.5N  74.8W    55 KTS
36HR VT     11/1200Z 37.5N  71.0W    60 KTS
48HR VT     12/0000Z 40.5N  64.5W    60 KTS...EXTRATROPICAL
72HR VT     13/0000Z 51.0N  51.0W    55 KTS...EXTRATROPICAL
 
 
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