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HURRICANE HUMBERTO DISCUSSION NUMBER  10
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SUN SEP 23 2001
 
AN AIR FORCE RECON RECENTLY FOUND A 984 MB CENTRAL PRESSURE AND 86
KT AT 700 MB TO THE NORTHEAST OF THE CENTER.  A GPS DROP NEAR THE
EYEWALL MEASURED ONLY 56 KNOTS AT THE SURFACE BUT IT IS ASSUMED THAT
THERE IS MORE VERTICAL MIXING NEARBY AND THE INITIAL WIND SPEED
IS INCREASED TO 70 KT.  A 90 PERCENT REDUCTION OF THE 700 MB WIND
SPEED WOULD GIVE 75 KNOTS.  THE MEAN BOUNDARY LAYER WIND SPEED IN 
THE DROP WAS 79 KT.  SOME OF MY COLLEAGUES PREFER 75 KNOTS FOR 
THEINITIAL WIND SPEED BUT I AM MORE CONSERVATIVE.  A LITTLE MORE 
STRENGTHENING IS FORECAST FOR 24 HOURS FOLLOWED BY SLOW WEAKENING 
UNDER INCREASING VERTICAL SHEAR.
 
THE INITIAL MOTION IS 360/09.  THE FORECAST SCENARIO IS UNCHANGED
FROM EARLIER.  HUMBERTO IS MOVING AROUND THE WESTERN PERIPHERY OF A
MID LEVEL SUBTROPICAL HIGH PRESSURE RIDGE.  THE NEW TRACK IS
ADJUSTED SLIGHTLY TO THE RIGHT OF THE PREVIOUS FORECAST AND SLIGHTLY
SLOWER.  THIS FOLLOWS A CONSENSUS OF THE GUIDANCE AND IS CLOSE TO
THE AVIATION MODEL EXCEPT AT 72 HOURS WHEN THE AVIATION MODEL TURNS
THE MOTION MORE TO THE RIGHT OR EAST-NORTHEASTWARD.  THE NOGAPS IS
LEFT AND FASTER AND BRINGS THE CENTER ACROSS THE CANADIAN MARITIMES.
 THE GFDL IS FARTHEST TO THE RIGHT AND SLOWER.
 
THE CENTER IS NEAR ITS POINT OF CLOSEST APPROACH TO BERMUDA.  
INTERESTS IN BERMUDA SHOULD MONITOR THE PROGRESS OF HUMBERTO UNTIL 
IT MOVES AWAY.
 
FORECASTER LAWRENCE
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     23/2100Z 32.3N  67.4W    70 KTS
12HR VT     24/0600Z 33.4N  67.5W    80 KTS
24HR VT     24/1800Z 35.2N  67.4W    80 KTS
36HR VT     25/0600Z 37.6N  66.5W    75 KTS
48HR VT     25/1800Z 40.0N  65.0W    70 KTS
72HR VT     26/1800Z 44.0N  58.9W    60 KTS
 
 
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