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HURRICANE HUMBERTO DISCUSSION NUMBER  20
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT WED SEP 26 2001
 
HUMBERTO HAS PRESENTED A PERSISTENT EYE OVERNIGHT SURROUNDED BY DEEP
CONVECTION.  DVORAK INTENSITY ESTIMATES ARE UP...77 KT FROM TAFB AND
65 FROM SAB...AND SO THE INTENSITY IS RAISED TO 70 KT FOR THIS
ADVISORY.  THE IMPROVED APPEARANCE WAS COINCIDENT WITH A JOG TO THE
NORTH...AND WAS PROBABLY IN RESPONSE TO RIDGING NEAR THE CYCLONE
DOWNSTREAM OF THE LARGE CUTOFF LOW OVER THE GREAT LAKES.
 
AFTER THE JOG...THE MOTION HAS RETURNED TO 050/9.  WITH THE RETURN 
OF THE MORE EASTWARD TRACK...THE EFFECT OF THE PROTECTIVE RIDGE IS 
EXPECTED TO LESSEN.  STRONGER WESTERLY FLOW WILL GRADUALLY
IMPINGE ON THE STORM IN THE NEXT 24-48 HR...WHICH SHOULD PRODUCE A
FASTER EAST-NORTHEASTWARD OR EASTWARD MOTION.  THE OFFICIAL FORECAST 
ESSENTIALLY UPDATES THE PREVIOUS ONE FOR THE TEMPORARY TRACK 
DEFLECTION AND IS CLOSE TO THE AVN SOLUTION.

HUMBERTO IS OVER THE STRONG SEA SURFACE TEMPERATURE GRADIENT NORTH
OF THE GULF STREAM AND IS FORECAST TO MOVE INTO COLDER WATER.  THIS
SHOULD LEAD TO EXTRATROPICAL TRANSITION IN ABOUT 36 TO 48 HR.  AS
THE SYSTEM ACCELERATES...IT IS LIKELY TO LOSE ITS SURFACE
CIRCULATION AND DISSIPATE BEFORE THE END OF THE FORECAST PERIOD.

FORECASTER FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     26/0900Z 40.7N  59.7W    70 KTS
12HR VT     26/1800Z 41.7N  57.7W    60 KTS
24HR VT     27/0600Z 42.1N  54.3W    50 KTS
36HR VT     27/1800Z 42.5N  49.6W    40 KTS...BECOMING EXTRATROPICAL
48HR VT     28/0600Z 42.5N  44.0W    35 KTS...EXTRATROPICAL
72HR VT     29/0600Z...DISSIPATED
 
 
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