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HURRICANE HUMBERTO DISCUSSION NUMBER  11
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT SUN SEP 23 2001

OBSERVATIONS FROM A MULTI-AIRCRAFT RESEARCH MISSION...CAMEX...
INDICATE THAT HUMBERTO HAS STRENGTHENED FURTHER.  EYEWALL DROPSONDE
DATA FROM A NOAA AIRCRAFT SHOWED AN 87 KNOT WIND SPEED AT THE
SURFACE IN THE NORTHEAST QUADRANT.  THERE WERE ALSO SURFACE WIND
MEASUREMENTS OF ABOUT THE SAME MAGNITUDE BY THE STEPPED FREQUENCY
MICROWAVE RADIOMETER...SFMR...INSTRUMENT ON BOARD THE AIRCRAFT.
LOWER LAYER AVERAGE WINDS FROM THE DROPSONDES YIELDED A SOMEWHAT
LOWER WIND SPEED...BUT MAY BE BIASED BY THE VERTICAL TILT OF THE
EYEWALL.  THEREFORE THE CURRENT INTENSITY IS ESTIMATED TO BE 85
KNOTS.  THE CENTRAL PRESSURE...983 MB...WOULD NOT NORMALLY SUPPORT
SUCH STRENGTH.  HOWEVER HUMBERTO IS EMBEDDED IN A HIGHER-THAN-NORMAL
SEA LEVEL PRESSURE ENVIRONMENT...WHICH IS LIKELY ENHANCING THE
GRADIENT.  THE HURRICANE HAS PROBABLY REACHED ITS PEAK INTENSITY.
THERE ARE STRONG HIGH-LEVEL WESTERLIES TO THE NORTH OF THE SYSTEM
AND THESE WESTERLIES SHOULD SOON CAUSE A SUBSTANTIAL INCREASE IN
VERTICAL SHEAR.  SINCE THE ENVIRONMENT IN HUMBERTO'S PATH SEEMS SO
UNFAVORABLE...THE FORECASTED WEAKENING IS AT A LITTLE GREATER RATE
THAN THAT SHOWN BY THE SHIPS GUIDANCE

INITIAL MOTION IS JUST SLIGHTLY EAST OF DUE NORTH...010/9.  THE FLOW 
AHEAD OF A DEEPENING 500 MB TROUGH OVER THE EASTERN U.S. SHOULD 
CARRY HUMBERTO ON A NORTH TO NORTHEASTWARD TRACK OVER THE NEXT 
COUPLE OF DAYS.  NEAR THE END OF THE PERIOD...THE SYSTEM SHOULD 
ENCOUNTER FASTER AND MORE ZONAL STEERING FLOW IN THE MID-LATITUDE 
WESTERLIES...SO HUMBERTO SHOULD BEGIN ACCELERATING EASTWARD BY THAT 
TIME.  THE OFFICIAL FORECAST TRACK IS BENT A LITTLE MORE TO THE 
RIGHT OF THE PREVIOUS FORECAST...IN LINE WITH THE LATEST NCEP GLOBAL 
MODEL GUIDANCE.

FORECASTER PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     24/0300Z 33.2N  67.0W    85 KTS
12HR VT     24/1200Z 34.5N  66.8W    80 KTS
24HR VT     25/0000Z 36.5N  66.4W    75 KTS
36HR VT     25/1200Z 38.6N  65.4W    70 KTS
48HR VT     26/0000Z 40.5N  63.5W    65 KTS
72HR VT     27/0000Z 43.0N  56.0W    55 KTS
 
 
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