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HURRICANE ALETTA DISCUSSION NUMBER  16
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT FRI MAY 26 2000
 
SATELLITE MICROWAVE IMAGERY FROM THE NRL WEB PAGE AT 0402Z SHOWS
THAT THE LOW-LEVEL CENTER OF ALETTA IS ON THE EASTERN EDGE OF
INCREASINGLY RAGGED DEEP CONVECTION...WHICH WOULD SUGGEST THAT
ALETTA IS WEAKENING UNDER THE INFLUENCE OF EASTERLY SHEAR.  DVORAK
INTENSITY ESTIMATES FROM TAFB AND SAB ARE 77 AND 90 KT...
RESPECTIVELY...WITH THE TAFB ESTIMATE MORE CONSISTENT WITH THE
CURRENT STRUCTURE AS REVEALED BY THE MICROWAVE IMAGERY.  THE
OFFICIAL INTENSITY IS LOWERED TO 75 KT WITH THIS ADVISORY.  THE
SHIPS INTENSITY FORECAST MODEL INDICATES LITTLE CHANGE IN STRENGTH
OVER THE NEXT 36-48 HOURS WITH SOME WEAKENING THEREAFTER.  IF THE
TRACK FORECAST IS CORRECT...ALETTA WILL BE GRADUALLY APPROACHING
COOLER WATER OVER THE NEXT THREE DAYS AND MAY BEGIN TO ENTRAIN MORE
STABLE AIR INTO THE CIRCULATION.  THE OFFICIAL FORECAST CALLS FOR
WEAKENING ONLY SLIGHTLY MORE RAPIDLY THAN THE SHIPS GUIDANCE.

ALETTA HAS MOVED LITTLE OVER THE PAST 24 HOURS.  THE TRACK GUIDANCE
AVAILABLE FOR THIS ADVISORY IS WIDELY DIVERGENT...AND COMPLICATED BY
THE SEEMINGLY OVER-AGRESSIVE SPIN-UP OF A NEW CYCLONE BEHIND ALETTA
IN THE AVIATION MODEL.  THE LBAR AND UKMET INDICATE A RELATIVELY
RAPID MOTION...GIVEN THE CURRENT LACK OF SAME...TO THE WEST-
NORTHWEST OVER THE NEXT THREE DAYS.  THE GFDL TAKES THE SYSTEM
SLOWLY BACK TO THE EAST FOR 36 HOURS FOLLOWED BY A GRADUAL TURN TO
THE NORTH AND NORTH-NORTHWEST.  THE OFFICIAL FORECAST NUDGES THE
PREVIOUS ADVISORY TRACK TO THE RIGHT...IN THE DIRECTION OF THE
GFDL...AND IS A COMPROMISE BETWEEN THE TWO SCENARIOS.  
 
THE INITIAL WIND RADII HAVE BEEN ADJUSTED TO REFLECT THE CURRENT
ASYMMETRIC DISTRIBUTION OF CONVECTION ABOUT THE CENTER.

FORECASTER FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     26/0900Z 14.7N 107.5W    75 KTS
12HR VT     26/1800Z 14.7N 107.5W    70 KTS
24HR VT     27/0600Z 15.1N 108.1W    70 KTS
36HR VT     27/1800Z 15.5N 108.9W    70 KTS
48HR VT     28/0600Z 16.0N 109.5W    65 KTS
72HR VT     29/0600Z 17.0N 110.0W    60 KTS
 
 
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