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#35706 (Received by flhurricane at: 10:40 AM 27.Jul.2005) TCDAT1 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 |