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Tropical Storm FRANKLIN


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TROPICAL STORM FRANKLIN DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT SUN JUL 24 2005
 
FRANKLIN IS BEING AFFECTED BY STRONG NORTHWESTERLY VERTICAL WIND
SHEAR THIS EVENING.  THE LOW-LEVEL CENTER IS NOW COMPLETELY
EXPOSED...AND THE CONVECTIVE BURSTS TO THE SOUTHEAST ARE GENERALLY
GETTING FARTHER AWAY FROM THE CENTER.  SATELLITE INTENSITY
ESTIMATES ARE 45 KT FROM TAFB...AND 35 KT FROM SAB AND AFWA.  BASED
ON THESE...THE INITIAL INTENSITY IS REDUCED TO 40 KT.

INTERESTING CHANGES HAVE OCCURRED IN THE MOTION THIS EVENING. 
FRANKLIN STOPPED MOVING EAST-NORTHEASTWARD JUST AFTER 18Z...AND FOR
THE PAST SEVERAL HOURS HAS DRIFTED SOUTH-SOUTHWEST.  THIS MOTION...
WHICH WAS POORLY FORECAST BY THE DYNAMICAL GUIDANCE...IS LIKELY DUE
TO A BUILDING LOW-LEVEL RIDGE NORTH OF FRANKLIN IN THE WAKE OF THE
PREVIOUS UPPER-LEVEL TROUGH AND COLD FRONT.  LARGE-SCALE MODELS
FORECAST THIS RIDGE TO START WEAKENING IN 12 HR OR SO IN FRONT OF
THE NEXT MID-LATITUDE TROUGH...WHICH SHOULD ALLOW FRANKLIN TO
RESUME THE EAST-NORTHEASTWARD MOTION FORECAST BY THE DYNAMICAL
MODELS.  THIS MOTION WILL LIKELY BE UNSTEADY...AS THE NEW TROUGH
WILL LIKELY NOT BE STRONG ENOUGH TO WHISK FRANKLIN AWAY AND A FINAL
NORTHEASTWARD ACCELERATION MAY HAVE TO WAIT FOR A THIRD TROUGH IN
3-4 DAYS TIME.  THE OFFICIAL FORECAST TRACK IS SLOWER AND SHIFTED
SOUTHWARD FROM THE PREVIOUS FORECAST.  IT SHOULD BE NOTED THAT THE
SHALLOW-STEERING BAMS CALLS FOR FRANKLIN TO DO A LOOP BETWEEN
BERMUDA AND THE U. S. FOR THE NEXT 5 DAYS.

THE UPPER-LEVEL ENVIRONMENT IS CURRENTLY UNFAVORABLE...AND IF THE
GFS AND THE CANADIAN ARE CORRECT IT WILL NOT BE GETTING FAVORABLE
FOR AT LEAST 48-72 HR.  THE UKMET AND NOGAPS FORECAST A LESS
HOSTILE...ALTHOUGH LESS THAN IDEAL...UPPER-LEVEL WIND PATTERN AFTER
48 HR...WHICH COULD ALLOW FRANKLIN TO RE-INTENSIFY IF THOSE MODELS
ARE CORRECT.  THE SHIPS MODEL FORECASTS STEADY WEAKENING THROUGH
120 HR...WHILE THE GFDL AND GFDN SHOW SOME INTENSIFICATION AFTER
24-36 HR.  THE INTENSITY FORECAST WILL GO WITH THE SHIPS
SCENARIO...BUT MAINTAIN A HIGHER INTENSITY THAN THE SHIPS FORECAST
DUE TO THE UNCERTAINTIES IN THE FORECAST UPPER-LEVEL WINDS.

THE STALLING DELAYS THE NEED FOR TROPICAL STORM WATCHES OF WARNING
FOR BERMUDA.  HOWEVER...THEY MAY BE REQUIRED ON MONDAY.
 
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      25/0300Z 30.9N  71.6W    40 KT
 12HR VT     25/1200Z 30.8N  71.6W    40 KT
 24HR VT     26/0000Z 31.0N  70.3W    35 KT
 36HR VT     26/1200Z 31.7N  68.5W    35 KT
 48HR VT     27/0000Z 32.5N  67.2W    30 KT
 72HR VT     28/0000Z 34.0N  65.0W    25 KT
 96HR VT     29/0000Z 36.5N  61.5W    25 KT
120HR VT     30/0000Z 40.0N  55.0W    25 KT...DISSIPATING
 
 
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