Tropical Storm FRANKLIN

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TROPICAL STORM FRANKLIN DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT FRI JUL 22 2005
 
WHILE THE CONVECTIVE TOPS ARE COOLING AS THE DIURNAL MAXIMUM
APPROACHES...FRANKLIN HAS A SOMEWHAT RAGGED APPEARANCE IN SATELLITE
IMAGERY THIS MORNING.  THE CENTRAL CONVECTION IS POORLY
ORGANIZED...WITH THE STRONGEST CLUSTER EAST OF THE CENTER.  SURFACE
REPORTS FROM GREAT ABACO HAVE NOT YET SHOWN THE TIGHT CENTER
REPORTED BY THE RECONNAISSANCE AIRCRAFT YESTERDAY AFTERNOON.  THE
INITIAL INTENSITY WILL REMAIN 40 KT...WHICH IS A LITTLE ABOVE THE
SATELLITE INTENSITY ESTIMATES OF 35 KT FROM ALL AGENCIES.  A NEW
RECONNAISSANCE AIRCRAFT SHOULD REACH FRANKLIN AROUND 12Z.

THE INITIAL MOTION IS 305-310 AT 10 KT.  FRANKLIN IS HEADING FOR A
WEAKNESS IN THE SUBTROPICAL RIDGE EAST OF FLORIDA AS A DEEP LAYER
TROUGH AND ASSOCIATED FRONTAL SYSTEM MOVE SOUTHEASTWARD FROM THE
CENTRAL AND EASTERN UNITED STATES.  THE DYNAMICAL MODEL GUIDANCE
RESPOND TO THIS PATTERN BY RECURVING FRANKLIN TO THE NORTHEAST AND
ACCELERATING IT OUT TO SEA.  THIS INCLUDES BOTH THE GFS AND
UKMET...WHICH WERE CALLING FOR THE STORM TO STALL IN EARLIER RUNS. 
HOWEVER...THE BAMM AND BAMD STILL CALL FOR FRANKLIN TO TURN
WESTWARD AFTER 36 HR...WHILE THE NHC98 CALLS FOR A 5-DAY LOOP NEAR
THE NORTHERN BAHAMAS.  THESE SCENARIOS ARE POSSIBLE IF FRANKLIN
MISSES CONNECTING WITH THE ONCOMING TROUGH.  THE OFFICIAL FORECAST
WILL COMPROMISE BETWEEN THESE EXTREMES...CALLLING FOR FRANKLIN TO
RECURVE NORTHEASTWARD AT A SIGNIFICANTLY FASTER FORWARD SPEED THAN
THE PREVIOUS FORECAST...BUT AT A SIGNIFICANTLY SLOWER FORWARD SPEED
THEN THE DYNAMICAL MODELS.

FRANKLIN IS CURRENTLY LOCATED UNDER AN UPPER-LEVEL CYCLONIC SHEAR
AXIS...WITH WESTERLY UPPER-LEVEL WEST OF THE AXIS TRYING TO PUSH
THE AXIS ACROSS THE CENTER AND PRODUCE SHEAR.  THIS SHOULD AT LEAST
SLOW INTENSIFICATION IN THE SHORT TERM.  IN THE LONGER TERM...HOW
FAST FRANKLIN MOVES OFF TO THE NORTHEAST WILL DETERMINE HOW
FAVORABLE CONDITIONS ARE FOR STRENGTHENING.  A FASTER MOTION WOULD
PLACE THE STORM EAST OF THE ONCOMING UPPER-LEVEL TROUGH...WHICH
WOULD ALLOW MORE STRENGTHENING.  A SLOWER MOTION WOULD ALLOW THE
TROUGH TO RUN OVER THE STORM AND EXPOSE IT TO NORTHERLY SHEAR.  THE
GFDL...WHICH NOW RACES THE STORM OFF TO THE NORTHEAST...NEVER
STRENGTHENS IT ABOVE 60 KT...AND THE OTHER INTENSITY GUIDANCE DOES
NOT STRENGTHEN IT MUCH ABOVE 65 KT.  THE INTENSITY FORECAST IS AN
UPDATE OF THE PREVIOUS FORECAST AND A COMPROMISE BETWEEN THE GFDL
AND SHIPS MODELS.

FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0900Z 26.7N  77.3W    40 KT
 12HR VT     22/1800Z 27.6N  77.7W    45 KT
 24HR VT     23/0600Z 29.0N  77.6W    50 KT
 36HR VT     23/1800Z 29.9N  76.8W    55 KT
 48HR VT     24/0600Z 30.5N  75.5W    55 KT
 72HR VT     25/0600Z 31.5N  73.0W    60 KT
 96HR VT     26/0600Z 32.5N  69.0W    60 KT
120HR VT     27/0600Z 34.0N  64.0W    60 KT
 
 
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