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HURRICANE ALBERTO DISCUSSION NUMBER  13
NATIONAL WEATHER SERVICE MIAMI FL
5 AM AST MON AUG 07 2000
 
ALBERTO HAS INTENSIFIED SLIGHTLY DURING THE PAST 6 HOURS BASED ON
SATELLITE INTENSITY ESTIMATES OF 75 TO 85 KT FROM SAB AND TAFB...AND
OBJECTIVE DVORAK INTENSITY ESTIMATES OF 80 TO 85 KT. THEREFORE...THE
INITIAL INTENSITY IS INCREASED TO 80 KT. OUTFLOW REMAINS GOOD IN ALL
QUADRANTS AND A WELL-DEFINED POLEWARD OUTFLOW CHANNEL HAS DEVELOPED.

INITIAL MOTION IS 285/13. ALBERTO HAS MADE ITS NIGHTLY WESTWARD
WOBBLE AGAIN AND THE MOTION OVER THE PAST 9 HOURS HAS ACTUALLY BEEN
CLOSE TO 270 DEGREES. HOWEVER...THE TREND OVER THE PAST 36 HOURS HAS
BEEN CLOSE TO 285 DEGREES. ALBERTO IS EXPECTED TO STAY ON A GENERAL
WEST-NORTHWEST TRACK THROUGH MOST OF THE PERIOD. THE NEW 00Z UKMET
MODEL TAKES ALBERTO SHARPLY OFF TO THE NORTHWEST. HOWEVER...THE
CURRENT POSITION IS AT LEAST 60 NM SOUTH OF THE UKMET 12Z FORECAST
POSITION SO WE HAVE PLACED LITTLE WEIGHT ON THE UKMET SCENARIO.
THERE IS CONSIDERABLE DIVERGENCE AMONG THE FORECAST MODELS AFTER 24
HOURS WITH SOME TAKING ALBERTO DUE NORTH. IT APPEARS THAT THE GLOBAL
MODELS ARE PLACING TOO MUCH STEERING EMPHASIS ON THE UPPER-LEVEL
TROUGH TO THE NORTHWEST...WHICH ONLY APPEARS TO BE ENHANCING THE
OUTFLOW AT THIS TIME. THE OFFICIAL FORECAST IS A LITTLE TO THE LEFT
OF THE PREVIOUS FORECAST...AND CLOSE TO CLIPER AND THE 00Z NOGAPS
MODEL. IT IS POSSIBLE THAT THE UPPER-LEVEL TROUGH MAY BYPASS ALBERTO
TO THE NORTH...WHICH COULD POSSIBLY RESULT IN A MORE WESTWARD TRACK
THAN THE OFFICIAL FORECAST IS INDICATING AFTER 48 HOURS.

THE AFOREMENTIONED UPPER-LEVEL TROUGH NORTHWEST OF ALBERTO HAS
HELPED CREATE A POLEWARD OUTFLOW CHANNEL. BUOYS LOCATED JUST WEST OF
ALBERTO INDICATE THE HURRICANE IS NOW MOVING OVER WARMER...26C...
SSTS AND SOME SLIGHT INTENSIFICATION IS STILL POSSIBLE UNTIL ALBERTO
ENCOUNTERS SOME NORTHWESTERLY SHEAR AFTER 36 HOURS. THE SHIPS
INTENSITY MODEL ACTUALLY TAKES ALBERTO DOWN FROM THE CURRENT 80 KT
TO 70 KT IN 36 HOURS...DESPITE MOVING OVER WARMER WATER AND LITTLE
CHANGE IN THE VERTICAL SHEAR WHICH SEEMS A LITTLE EXCESSIVE.
HOWEVER...WATER VAPOR IMAGERY INDICATES SOME DRY AIR BEGINNING TO
WRAP INTO THE SYSTEM FROM THE SOUTHWEST WHICH MAY INHIBIT ANY
SIGNIFICANT DEVELOPMENT FOR AWHILE.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     07/0900Z 16.2N  40.3W    80 KTS
12HR VT     07/1800Z 16.7N  42.3W    85 KTS
24HR VT     08/0600Z 17.4N  44.6W    85 KTS
36HR VT     08/1800Z 18.4N  46.8W    85 KTS
48HR VT     09/0600Z 19.5N  49.0W    85 KTS
72HR VT     10/0600Z 22.0N  53.0W    80 KTS
  
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