Tropical Storm FRANKLIN

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TROPICAL STORM FRANKLIN DISCUSSION NUMBER  25
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT WED JUL 27 2005
 
THE LOW LEVEL CENTER REMAINS EXPOSED ON THE NORTH SIDE OF A LARGE
AREA OF DEEP CONVECTION. DURING THE PAST COUPLE OF HOURS...CLOUD
TOPS HAVE COOLED TO -80C AND THUNDERSTORMS HAVE DEVELOPED CLOSER TO
THE LOW-LEVEL CENTER. A 1017Z QUIKSCAT OVERPASS INDICATED SEVERAL
UNFLAGGED 35-KT WIND VECTORS IN THE SOUTHERN SEMICIRCLE...
INCLUDING A FEW 40-KT UNFLAGGED VECTORS. THIS IS THE BASIS FOR
INCREASING THE INITIAL INTENSITY TO 40 KT AND FOR MODIFYING THE
34-KT WIND RADII.
 
FRANKLIN CONTINUES TO MAKE SMALL WOBBLES ABOUT A MEAN MOTION TO THE
NORTH-NORTHWEST...OR 335/05. AS A MID- TO UPPER-LEVEL TROUGH AND
ASSOCIATED FRONTAL SYSTEM CURRENTLY OVER THE GREAT LAKES AND
MID-MISSISSIPPI VALLEY CONTINUES TO PROGRESS EASTWARD...THE
STEERING FLOW WILL GRADUALLY BECOME BETTER DEFINED FROM THE
SOUTHWEST. THIS SHOULD HELP TO ACCELERATE FRANKLIN TO THE NORTH AND
EVENTUALLY NORTHEAST. HOWEVER...UNTIL THE DEEP-LAYER STEERING FLOW
BECOMES ESTABLISHED...FRANKLIN MAY CONTINUE TO MAKE SMALL WOBBLES
IN THE TRACK...BUT GENERALLY IN A NORTHWARD DIRECTION. THE OFFICIAL
FORECAST TRACK IS A LITTLE LEFT OF THE PREVIOUS TRACK THROUGH 24
HOURS...BUT ONLY TO ACCOUNT FOR THE MORE WESTWARD INITIAL
POSITION...AND IS THEN BASICALLY BACK ON TRACK AFTER THAT. THIS IS
CONSISTENT WITH THE NHC MODEL CONSENSUS THROUGH 36 HOURS. AFTER
THAT...THE TRACK IS CLOSE TO THE GFS...GFDL...AND NOGAPS MODELS
SINCE THE UKMET TRACKER ALGORITHM ERRONEOUSLY LOCKED ONTO AN
EXTRATROPICAL LOW OVER THE FAR NORTHERN CANADIAN MARITIMES.

DEEP CONVECTION HAS GRADUALLY BEEN REDEVELOPING AND PROPAGATING UP
THE SOUTHWEST AND WEST SIDE OF THE CYCLONE OVER THE PAST 3-4 HOURS.
THIS IS IN RESPONSE TO THE UPPER-LEVEL SHEAR VECTOR SHIFTING FROM
THE NORTH TO THE EAST. THE SHIPS MODEL AND SOME OF THE OTHER GLOBAL
MODELS INDICATE THAT THE SHEAR VECTOR WILL CONTINUE TO GRADUALLY
SWING AROUND FROM EAST TO SOUTH AND FINALLY SOUTHWEST BY 36 HOURS
...WITH SHEAR VALUES ONLY AROUND 5 KT. THIS SHOULD ALLOW FOR DEEP
CONVECTION TO GRADUALLY DEVELOP OVER OR NEAR THE LOW-LEVEL CENTER
AND BRING ABOUT AT LEAST SOME MODEST RE-INTENSIFICATION UNTIL
FRANKLIN REACHES MUCH COLDER SSTS IN 42-48 HOURS AND WEAKENS AGAIN.
 
FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/1500Z 33.4N  69.2W    40 KT
 12HR VT     28/0000Z 34.5N  69.1W    40 KT
 24HR VT     28/1200Z 36.4N  67.8W    45 KT
 36HR VT     29/0000Z 38.4N  65.7W    45 KT
 48HR VT     29/1200Z 40.4N  62.8W    35 KT...BECOMING EXTRATROPICAL
 72HR VT     30/1200Z 44.5N  55.0W    30 KT...EXTRATROPICAL
 96HR VT     31/1200Z...ABSORBED BY FRONTAL SYSTEM

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