ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ANDREA DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL012013 1100 AM EDT THU JUN 06 2013 EVEN THOUGH THE RADAR PRESENTATION OF ANDREA HAS BEEN IMPROVING DURING THE PAST FEW HOURS...CONVECTIVE CLOUD TOPS NEAR THE CENTER OF CIRCULATION HAVE BEEN WARMING. THE STRONGEST CONVECTION REMAINS LOCATED IN A BAND THAT IS MOVING ONSHORE THE WEST COAST OF FLORIDA AT THIS TIME...AND THE TAMPA WSR-88D HAS BEEN SHOWING 65-70 KT AT ABOUT 6500 FT. THE INITIAL INTENSITY IS BEING HELD AT 50 KT PENDING THE NEXT AIR FORCE RECONNAISSANCE MISSION THIS AFTERNOON. ANDREA HAS TURNED NORTHEASTWARD AND IS BEGINNING TO ACCELERATE WITH AN INITIAL MOTION OF 035/13 KT. THE STORM IS LOCATED JUST TO THE EAST OF A MID- TO UPPER-LEVEL TROUGH AXIS...AND IT IS GETTING CLOSER TO FASTER MID-LATITUDE FLOW LOCATED OVER THE TENNESSEE VALLEY. THIS FLOW IS EXPECTED TO CAUSE ANDREA TO RACE NORTHEASTWARD ALONG THE EAST COAST OF THE UNITED STATES DURING THE NEXT 48 HOURS OR SO. THERE IS VERY LITTLE SPREAD AMONG THE TRACK GUIDANCE...AND ESSENTIALLY NO CHANGES WERE REQUIRED FROM THE PREVIOUS OFFICIAL TRACK FORECAST. GIVEN THE CONFLICTING SIGNALS IN RADAR AND SATELLITE DATA...THERE IS NO STRONG EVIDENCE THAT ANDREA WILL STRENGTHEN MUCH BEFORE IT REACHES THE COAST LATER TODAY. AFTER THE CENTER MOVES INLAND... SOME WEAKENING IS EXPECTED...BUT MOST OF THE INTENSITY GUIDANCE INDICATE THAT ANDREA WILL MAINTAIN TROPICAL-STORM INTENSITY THROUGH THE FORECAST PERIOD. THE MAIN QUESTION IS WHEN EXTRATROPICAL TRANSITION WILL BE COMPLETE. THE GLOBAL MODEL FIELDS DO NOT SHOW STRONG BAROCLINICITY UNTIL ABOUT 48 HOURS...BUT THE FSU PHASE-SPACE DIAGRAMS BASED ON THE GFS SUGGEST THAT THE TRANSITION COULD BE COMPLETE BY 36 HOURS. FOR NOW...THE OFFICIAL FORECAST WILL KEEP ANDREA AS TROPICAL UNTIL 36 HOURS. THERE ARE NO CHANGES TO THE TROPICAL STORM WARNINGS ON THIS ADVISORY. BASED ON THE ASSUMPTION THAT ANDREA WILL BECOME POST-TROPICAL IN 36 TO 48 HOURS...WE DO NOT EXPECT TO EXTEND THE TROPICAL WARNINGS ANY FURTHER NORTH ALONG THE COAST. OUR CURRENT INTENTION IS THAT ANY HAZARDOUS WIND CONDITIONS FROM THE DELMARVA PENINSULA NORTHWARD TO NEW ENGLAND WOULD BE HANDLED BY LOCAL NATIONAL WEATHER SERVICE WARNING PRODUCTS. REGARDLESS OF THE EXACT TRACK OF THE CENTER OF ANDREA...THE PRIMARY EFFECTS ARE EXPECTED TO BE HEAVY RAINFALL ACROSS MUCH OF THE FLORIDA PENINSULA AND INTO THE COASTAL SECTIONS OF THE SOUTHEASTERN UNITED STATES...STORM SURGE FLOODING ALONG PORTIONS OF THE WEST COAST OF FLORIDA...AND ISOLATED TORNADOES TODAY ACROSS THE FLORIDA PENINSULA. FORECAST POSITIONS AND MAX WINDS INIT 06/1500Z 28.2N 84.3W 50 KT 60 MPH 12H 07/0000Z 30.3N 82.9W 45 KT 50 MPH...INLAND 24H 07/1200Z 33.4N 80.1W 40 KT 45 MPH...INLAND 36H 08/0000Z 37.3N 76.0W 40 KT 45 MPH...INLAND 48H 08/1200Z 41.8N 70.2W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 09/1200Z 46.5N 54.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 10/1200Z 47.0N 33.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 11/1200Z 52.0N 20.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ FORECASTER BERG/BEVEN NNNN