Tropical Storm FRANKLIN

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TROPICAL STORM FRANKLIN DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT FRI JUL 22 2005
 
DRY AIR HAS WRAPPED UP THE EAST SIDE AND INTO THE CENTER...WHICH HAS
ERODED THE DEEP CONVECTION NEAR THE INNER CORE. BANDING FEATURES
HAVE ALSO COME AND GONE DURING THE AFTERNOON IN SATELLITE IMAGERY
AND IN THE MELBOURNE RADAR DARA. AROUND 1532Z...AIR FORCE RECON
FOUND 53 KT FLIGHT-LEVEL WINDS IN THE SOUTHEAST QUADRANT...WHICH
EQUALS A 42-43 KT SURFACE WIND...WHILE THE ONBOARD METEOROLOGIST
AGAIN ESTIMATED SURFACE WINDS OF 55-60 IN THE SAME AREA. HOWEVER...
THAT CONVECTIVE BAND HAS SINCE DISAPPEARED DUE TO THE DRY AIR...SO
THOSE SURFACE WINDS WERE LIKELY ENHANCED BY STRONG DOWNDRAFTS. AS
SUCH...THE INTENSITY IS BEING MAINTAINED AT 45 KT...ESPECIALLY
SINCE THE PRESSURE HAS NOT FALLEN BELOW 1007 MB...AND THE CYCLONE
HAS A RAGGED LOOKING APPEARANCE IN SATELLITE AND RADAR IMAGERY.
 
THE INITIAL MOTION IS 360/08 KT. RECON AND RADAR POSITION ESTIMATES
INDICATE FRANKLIN HAS BEEN MOVING NORTHWARD AT A STEADY 8 KT OR SO
SINCE ABOUT 14Z. ACCORDING TO THE OVERWHELMING MAJORITY OF THE NHC
MODELS...THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT
24 HOURS WITH A GRADUAL TURN AND ACCELERATION TO THE NORTHEAST AND
EAST-NORTHEAST AFTER THAT. WATER VAPOR IMAGERY AND SPECIAL 18Z
UPPER-AIR DATA INDICATE THE SHORTWAVE TROUGH OVER THE EASTERN OHIO
AND TENNESSEE VALLEYS HAS CONTINUED TO MOVE EAST-SOUTHEASTWARD AND
SHOULD BE ALONG THE U.S. EAST COAST BY THIS TIME TOMORROW. IF THE
SHORTWAVE IS STRONG ENOUGH...THEN IT MAY ERODE THE SUBTROPICAL
RIDGE TO THE NORTH OF FRANKLIN...AND CAPTURE THE CYCLONE AND MOVE
IT AWAY FROM THE U.S. HOWEVER...THE GFS... UKMET...AND THE CANADIAN
MODELS NOW ONLY TAKE FRANKLIN AS FAR NORTH AS 30N LATITUDE IN 36-48
HOURS...AND THEN LEAVE THE MID-LEVEL CIRCULATION BEHIND WHILE THE
LOW-LEVEL CENTER MOVES QUICKLY NORTHEASTWARD AHEAD OF A COLD FRONT.
WHILE THIS SCENARIO IS POSSIBLE...IT WOULD MEAN THAT FRANKLIN WOULD
CEASE TO EXIST AS A TROPICAL CYCLONE. THOSE MODELS ALSO MOVE THE
MID-LEVEL CIRCULATION BACK TO THE SOUTH AND SOUTHWEST AFTER 72
HOURS...MUCH LIKE THE MEDIUM AND DEEP BAM MODELS. HOWEVER...THE
OFFICIAL FORECAST TRACK REMAINS SIMILAR TO THE PREVIOUS FORECAST
AND IS CLOSE TO THE NHC MODEL CONSENSUS.
 
THE SHEAR ACROSS FRANKLIN HAS INCREASED FROM THE WEST AGAIN DUE TO
THE OUTFLOW FROM THE DEEP CONVECTION ASSOCIATED WITH THE STRONG
YUCATAN DISTURBANCE. WATER VAPOR IMAGERY ALSO INDICATES FRANKLIN IS
GETTING PINCHED FROM THE EAST BY AN UPPER-LEVEL TROUGH DIGGING
SOUTHWESTWARD. THE UPPER-LEVEL FLOW PATTERN IS ONLY EXPECTED TO
SLOWLY BECOME MORE FAVORABLE FOR INTENSIFICATION TO OCCUR...AND
THIS IS REFLECTED IN THE SLOWER THAN NORMAL INTENSIFICATION
FORECASTS AS PER THE SHIPS INTENSITY MODEL. THE GFDL BRINGS
FRANKLIN UP TO 89 IN 48 HOURS...BUT THIS SEEMS OVERDONE...
ESPECIALLY WITH INCREASING WESTERLY MID- TO UPPER-LEVEL FLOW
FORECAST TO AFFECT THE SYSTEM AT THAT TIME.

FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/2100Z 27.8N  76.7W    45 KT
 12HR VT     23/0600Z 28.9N  76.4W    50 KT
 24HR VT     23/1800Z 30.0N  75.4W    55 KT
 36HR VT     24/0600Z 30.9N  73.8W    60 KT
 48HR VT     24/1800Z 31.5N  72.0W    60 KT
 72HR VT     25/1800Z 32.8N  67.6W    60 KT
 96HR VT     26/1800Z 34.0N  63.0W    60 KT
120HR VT     27/1800Z 37.0N  56.5W    60 KT
 
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