000 WTNT41 KNHC 130837 TCDAT1 TROPICAL STORM FRANKLIN DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL AL062011 500 AM EDT SAT AUG 13 2011 DURING THE PAST SEVERAL HOURS...SATELLITE IMAGES INDICATE THAT A LARGE BURST OF CONVECTION FORMED NEAR OR JUST TO THE EAST OF THE CENTER. AN AMSR-E MICROWAVE PASS AT 0553 UTC SUGGESTS THE CENTRAL FEATURES OF THE SYSTEM WERE BECOMING BETTER-DEFINED WITH MORE CURVATURE NOTED. DVORAK SATELLITE ESTIMATES WERE 30 KT AND 35 KT FROM TAFB/SAB WITH AN AMSU-BASED ESTIMATE FROM UW-CIMSS OF 37 KT. GIVEN THE SIGNIFICANT INCREASE IN THE CONVECTION AND STRUCTURAL IMPROVEMENTS IN MICROWAVE IMAGERY...THE INTENSITY IS SET TO 35 KT...MAKING THIS SYSTEM THE SIXTH TROPICAL STORM OF THE YEAR. FRANKLIN DOES NOT HAVE MUCH TIME LEFT TO INTENSIFY AS IT WILL SOON BE CROSSING THE 26C ISOTHERM. VERTICAL WIND SHEAR IS ALSO FORECAST TO INCREASE DUE TO AN UPPER-LEVEL TROUGH CATCHING THE STORM FROM BEHIND. THUS...ONLY A SMALL INCREASE IN STRENGTH IS SHOWN IN THE NHC FORECAST...SIMILAR TO A BLEND OF THE SHIPS AND LGEM MODELS. IT SHOULD BE NOTED THAT THESE TYPES OF NORTHEASTWARD MOVING SYSTEMS HAVE HISTORICALLY BEEN DIFFICULT TO FORECAST...AND IT WOULD NOT BE SURPRISING IF THE STORM BRIEFLY BECOMES A LITTLE STRONGER THAN PREDICTED. THE INITIAL MOTION HAS TURNED A LITTLE TO THE LEFT AND IS ESTIMATED AT 055/17. FRANKLIN IS BEING STEERED ALONG THE NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE WITHIN MID-LATITUDE WEST- SOUTHWESTERLY FLOW. MODEL GUIDANCE IS TIGHTLY CLUSTERED ON A TRACK TOWARD THE EAST-NORTHEAST TODAY...FOLLOWED BY A MOTION TOWARD THE EAST AS THE STORM MOVES AROUND THE RIDGE. THE LATEST FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS NHC ADVISORY...AND LIES JUST TO THE NORTH OF THE ATLANTIC MULTI-MODEL CONSENSUS. A COLD FRONT CAN BE SEEN A FEW HUNDRED MILES TO THE NORTHWEST OF FRANKLIN...AND THIS FEATURE...ALONG WITH COOLER SSTS AND INCREASING SHEAR...SHOULD CAUSE EXTRATROPICAL TRANSITION WITHIN ABOUT 24 HOURS. THE SYSTEM SMALL SYSTEM SHOULD BECOME ABSORBED BY THE FRONT IN ABOUT 3 DAYS. FORECAST POSITIONS AND MAX WINDS INIT 13/0900Z 37.9N 60.4W 35 KT 40 MPH 12H 13/1800Z 39.0N 57.4W 40 KT 45 MPH 24H 14/0600Z 40.0N 52.9W 40 KT 45 MPH...POST-TROP/EXTRATROP 36H 14/1800Z 40.4N 48.3W 35 KT 40 MPH...POST-TROP/EXTRATROP 48H 15/0600Z 40.0N 43.7W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 16/0600Z...DISSIPATED $$ FORECASTER BLAKE