Tropical Storm FRANKLIN

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TROPICAL STORM FRANKLIN DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT SUN JUL 24 2005
 
RECONNAISSANCE REPORTS UP UNTIL 06Z INDICATED THAT FRANKLIN WAS...AT
LEAST TO THAT POINT...HOLDING ITS OWN AGAINST NORTHWESTERLY SHEAR.
MAXIMUM FLIGHT LEVEL WINDS DURING THE PAST SEVERAL HOURS WERE 58
KT...AND A DROPSONDE AT 0516Z REPORTED 49 KT AT THE SURFACE IN THE
SOUTHEAST QUADRANT. THE LAST CENTRAL PRESSURE REPORTED BY THE
AIRCRAFT WAS BACK DOWN TO 1001 MB.  BASED ON THESE DATA...THE
INITIAL INTENSITY WILL BE HELD AT 55 KT. SINCE THE AIRCRAFT LEFT
THE CYCLONE HOWEVER...THE CENTER HAS BECOME MOSTLY EXPOSED ON THE
NORTHWEST EDGE OF A SMALL AREA OF COLD CONVECTION...WITH A RAGGED
BAND LOCATED WELL TO THE SOUTH AND SOUTHWEST OF THE CENTER.  THE
NEXT RECONNAISSANCE FLIGHT THIS AFTERNOON WILL LIKELY FIND A WEAKER
SYSTEM. 

THE MOTION HAS BEEN UNSTEADY BUT A SMOOTHED ESTIMATE IS 070/8. 
THERE IS STILL CONSIDERABLE UNCERTAINTY IN THE FORECAST TRACK AS
THE DYNAMICAL MODELS OFFER WIDELY DIFFERENT SCENARIOS.  THE UKMET
AND NOGAPS MAINTAIN A STRONG CYCLONE AND TAKE IT SLOWLY
NORTHEASTWARD ON THE NORTHWEST OF A BUILDING SUBTROPICAL RIDGE. 
THE OTHER EXTREME IS OFFERED BY THE GFS...WHICH CONTINUES WITH A
RAPID EAST-NORTHEASTWARD PROGRESSION OF A WEAK AND DECOUPLED
SYSTEM.  I LIKE THE IDEA OF A WEAK AND SHALLOW VORTEX...ESPECIALLY
GIVEN CURRENT TRENDS AND THE APPROACH OF DRY UPPER-LEVEL WESTERLY
FLOW...AS SEEN IN WATER VAPOR IMAGERY.  HOWEVER...THE GFS SEEMS WAY
TOO FAST AND I HAVE BASED THE OFFICIAL FORECAST MORE ON THE SHALLOW
BAM AND FSU SUPERENSEMBLE...AS WELL AS CONTINUITY WITH THE PREVIOUS
ADVISORY.

THE UPPER ENVIRONMENT LOOKS TO BE VERY HOSTILE FOR AT LEAST THE NEXT
24-48 HOURS...AND IF THE FORECAST TRACK IS AT ALL CORRECT...
FRANKLIN WILL BE MOVING OVER COOLER WATERS BY LATE IN THE FORECAST
PERIOD.  CONSEQUENTLY...A GRADUAL DECLINE IS FORECAST...BUT THE
CYCLONE COULD DISSIPATE MUCH MORE QUICKLY THAN INDICATED BY THE
OFFICIAL FORECAST.

FORECASTER FRANKLIN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/0900Z 30.5N  72.3W    55 KT
 12HR VT     24/1800Z 30.9N  70.8W    50 KT
 24HR VT     25/0600Z 31.3N  69.2W    45 KT
 36HR VT     25/1800Z 31.6N  67.8W    45 KT
 48HR VT     26/0600Z 32.0N  66.5W    40 KT
 72HR VT     27/0600Z 34.0N  63.5W    35 KT
 96HR VT     28/0600Z 36.0N  60.0W    30 KT
120HR VT     29/0600Z 39.0N  54.5W    25 KT...DISSIPATING
 
 
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