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HURRICANE HUMBERTO DISCUSSION NUMBER  21
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT WED SEP 26 2001

SURPRISINGLY...HUMBERTO HAS CONTINUED TO STRENGTHEN THIS MORNING.
THE 15 N MI DIAMETER EYE HAS BECOME BETTER DEFINED AND THE
SURROUNDING CLOUD TOPS HAVE COOLED.  DVORAK CLASSIFICATIONS FROM
TAFB AND SAB ARE AT T5.0...I.E. 90 KNOTS...AND THIS WIND SPEED IS
USED FOR THE CURRENT INTENSITY.  IT IS UNUSUAL TO SEE A HURRICANE
STRENGTHEN SO MUCH AT SUCH A HIGH LATITUDE.  HUBERTO HAS MANAGED TO 
STAY OVER 25-26 DEG C SSTS...JUST TO THE SOUTH OF THE SHARP SST 
GRADIENT.  MOREOVER...THE BUILDING OF THE UPPER-LEVEL RIDGE NEAR AND 
NORTH OF THE HURRICANE...TO THE EAST OF THE LARGE TROUGH OVER THE 
EASTERN UNITED STATES...HAS SHELTERED THE TROPICAL CYCLONE FROM THE 
STRONGER WESTERLIES.  NUMERICAL GUIDANCE INDICATES THAT THIS RIDGE 
WILL SOON FLATTEN.  THIS SHOULD CAUSE A SIGNIFICANT INCREASE IN THE 
EASTWARD STEERING FLOW AND WESTERLY SHEAR OVER HUMBERTO.  THEREFORE 
THE OFFICIAL FORECAST SHOWS CONSIDERABLE ACCELERATION...AND 
WEAKENING.  IN 2-3 DAYS THE SYSTEM SHOULD GET ABSORBED INTO A LARGE 
EXTRATROPICAL LOW OVER THE NORTH ATLANTIC.

INITIAL MOTION IS UNCHANGED FROM THE PREVIOUS ADVISORY...BUT AN 
INCREASE IN FORWARD SPEED APPEARS IMMINENT.  THE OFFICIAL TRACK 
FORECAST IS A LITTLE FASTER...SIMILAR TO THE LATEST AVN MODEL 
TRACK...AND SOMEWHAT FASTER THAN THE FLORIDA STATE UNIVERSITY 
SUPERENSEMBLE FORECAST.

FORECASTER PASCH/FORMOSA
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     26/1500Z 41.3N  58.7W    90 KTS
12HR VT     27/0000Z 42.2N  56.1W    80 KTS
24HR VT     27/1200Z 42.5N  50.0W    65 KTS
36HR VT     28/0000Z 42.5N  41.5W    55 KTS...BECOMING EXTRATROPICAL
48HR VT     28/1200Z 42.0N  33.0W    40 KTS...EXTRATROPICAL
72HR VT     29/1200Z...ABSORBED
 
 
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