000 WTNT42 KNHC 140855 TCDAT2 TROPICAL STORM RAFAEL DISCUSSION NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172012 500 AM AST SUN OCT 14 2012 SATELLITE IMAGERY...RADAR DATA...AND SURFACE OBSERVATIONS INDICATE RAFAEL HAS CONTINUED TO MOVE NORTHWARD TO NORTH-NORTHWESTWARD OVER THE PAST 6 HOURS. DOPPLER RADAR DATA FROM SAN JUAN ALSO INDICATES A NARROW BAND OF CONVECTION HAS NOW WRAPPED COMPLETELY AROUND THE CIRCULATION CENTER...SUGGESTING THAT THE CYCLONE IS GETTING BETTER ORGANIZED. FURTHERMORE...INFRARED AND WATER VAPOR SATELLITE IMAGERY INDICATE THE CIRRUS OUTFLOW PATTERN HAS EXPANDED IN THE WESTERN SEMICIRCLE...WHICH IS AN INDICATION THAT THE VERTICAL SHEAR HAS LESSENED. HOWEVER...THE OUTFLOW PATTERN IS STILL ELONGATED IN A NORTH-SOUTH CONFIGURATION. THE INITIAL INTENSITY IS BEING MAINTAINED AT 45 KT...GIVEN THAT CLOUD TOPS HAVE CONTINUED TO COOL AND THE ADT INTENSITY ESTIMATES HAVE BEEN STEADY AT T3.1/47 KT SINCE THE PREVIOUS ADVISORY. THE INITIAL MOTION ESTIMATE IS 340/11 KT. A FAIR PRESENTATION IN THE REFLECTIVITY AND DOPPLER VELOCITY DATA FROM SAN JUAN SUGGEST THAT RAFAEL HAS STARTED TO TURN TOWARD THE NORTH-NORTHWEST. THIS MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24 HOURS OR SO AS A DEEP-LAYER RIDGE BUILDS TO THE NORTH OF THE CYCLONE AND GRADUALLY SLIDES EASTWARD. AFTER THAT...A STRONG MID-TROPOSPHERIC TROUGH AND AN ASSOCIATED COLD FRONT ARE FORECAST TO MOVE ACROSS THE EASTERN UNITED STATES INTO THE WESTERN ATLANTIC BY 48 HOURS. THESE FEATURES ARE EXPECTED TO ERODE THE RIDGE TO THE NORTH OF RAFAEL...AND ALLOW CYCLONE TO RECURVE INTO THE HIGH-LATITUDE WESTERLIES. THE NHC GUIDANCE IS IN EXCELLENT AGREEMENT ON THIS DEVELOPING SCENARIO... EXCEPT FOR SLIGHT SPEED DIFFERENCES. THE 00Z ECMWF APPEARS TO BE A SLIGHT OUTLIER AFTER 72 HOURS...AND IS THE RIGHTMOST OF ALL OF THE MODELS DUE ITS MORE RAPID WEAKENING OF THE CYCLONE. THE OFFICIAL NHC FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY AND LIES IN THE MIDDLE OF THE TIGHTLY PACKED GUIDANCE ENVELOPE. RAFAEL REMAINS IN A MODERATE SOUTHWESTERLY VERTICAL SHEAR ENVIRONMENT...WHICH IS EXPECTED TO CONTINUE FOR THE NEXT 36-48 HR. HOWEVER...THERE MAY BRIEF PERIODS WHERE THE SHEAR ABATES...SUCH AS HAS BEEN HAPPENING SINCE THE PREVIOUS ADVISORY...THAT WILL ALLOW FOR RAFAEL TO STRENGTHEN. THE OFFICIAL INTENSITY FORECAST CONTINUES THE STRENGTHENING TREND FROM THE PREVIOUS ADVISORIES FOR THE NEXT 48 HOURS OR SO...FOLLOWED BY GRADUAL WEAKENING AS THE VERTICAL SHEAR INCREASES SHARPLY. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND CLOSELY FOLLOWS THE INTENSITY CONSENSUS MODELS. RAFAEL IS FORECAST TO BECOME EXTRATROPICAL BY 120 HR...IF NOT SOONER...WHEN THE CYCLONE BEGINS TO INTERACT WITH THE AFOREMENTIONED STRONG COLD FRONT. USERS ARE REMINDED NOT TO FOCUS ON THE EXACT TRACK OF THE CENTER DURING THE NEXT DAY OR SO...SINCE HEAVY RAIN AND WIND IMPACTS EXTEND WELL EAST AND SOUTHEAST OF THE CENTER. FORECAST POSITIONS AND MAX WINDS INIT 14/0900Z 19.4N 63.8W 45 KT 50 MPH 12H 14/1800Z 20.7N 64.5W 55 KT 65 MPH 24H 15/0600Z 22.5N 65.7W 60 KT 70 MPH 36H 15/1800Z 24.1N 66.0W 65 KT 75 MPH 48H 16/0600Z 27.1N 65.3W 70 KT 80 MPH 72H 17/0600Z 36.2N 60.4W 65 KT 75 MPH 96H 18/0600Z 46.1N 52.4W 55 KT 65 MPH 120H 19/0600Z 50.4N 44.0W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ FORECASTER STEWART