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HURRICANE ALBERTO DISCUSSION NUMBER  63
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SAT AUG 19 2000
 
ALBERTO HAS INTENSIFIED SLIGHTLY BASED ON OBJECTIVE DVORAK SATELLITE
INTENSITIES RANGING FROM 90 TO 100 KT. ALSO... SUBJECTIVE SATELLITE
INTENSITY ESTIMATES FROM TAFB...SAB...AND KGWC HAVE BEEN AT LEAST 90
KT FOR ALMOST 12 HOURS...SO THE INITIAL INTENSITY HAS BEEN INCREASED
TO 95 KT. THIS TAKES ALBERTO TO JUST BELOW CATEGORY THREE INTENSITY.
 
THE INITIAL MOTION IS 005/6.  THERE IS LITTLE CHANGE TO THE PREVIOUS
FORECAST TRACK OR PHILOSOPHY.  ALL OF THE MODELS ARE NOW TIGHTLY
CLUSTERED ALONG THE PREVIOUS NHC FORECAST TRACKS AND MOST OF THE
MODELS ARE NOW INDICATING THE GRADUAL ACCELERATION AND TURN TO THE
NORTHEAST AFTER 24 HOURS THAT WAS MENTIONED IN THE PREVIOUS
ADVISORY.  THE SHORTWAVE TROUGH OVER SOUTHEAST CANADA IS EXPECTED TO
PICK UP ALBERTO IN ABOUT 36 HOURS AND HELP TO RAPIDLY TRANSITION THE
CYCLONE TO AN EXTRATROPICAL SYSTEM AFTER 48 HOURS.  THE OFFICIAL
TRACK IS CLOSE TO THE PREVIOUS FORECASTS...AND BETWEEN THE GFDL AND
UKMET MODELS.
 
ALBERTO WILL BE TRACKING OVER PROGRESSIVELY COOLER WATER THROUGHOUT
THE FORECAST PERIOD.  HOWEVER...A TIGHT SST GRADIENT EXISTS ALONG
40N LATITUDE AND...AFTER 24 HOURS...ALBERTO WILL BE MOVING OVER 23C
TO 17C WATER.  A COMBINATION OF THE COLD WATER AND APPROACHING
BAROCLINIC ZONE SHOULD HASTEN THE CONVERSION TO AN EXTRATROPICAL
SYSTEM...BUT THE WIND FIELD WILL STILL TAKE SOME TIME TO SPIN DOWN
EVEN THOUGH ALBERTO WILL PROBABLY BE DEVOID OF ANY DEEP CONVECTION
NEAR THE CENTER AFTER 48 HOURS.

THE INTIAL 34-KT WIND RADII AND 12-FT SEAS RADII WERE ADJUSTED BASED
ON 18Z SHIP REPORTS AND A QUIKSCAT SURFACE WIND CONVERSION PLOT
PROVIDED BY THE HURRICANE RESEARCH DIVISION.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     19/2100Z 36.5N  48.1W    95 KTS
12HR VT     20/0600Z 37.5N  48.1W    90 KTS
24HR VT     20/1800Z 39.2N  47.8W    85 KTS
36HR VT     21/0600Z 41.1N  47.0W    80 KTS
48HR VT     21/1800Z 44.5N  45.5W    65 KTS...BECOMING EXTRATROPICAL
72HR VT     22/1800Z 48.5N  42.5W    55 KTS...EXTRATROPICAL
 
 
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