000 WTNT42 KNHC 130233 TCDAT2 TROPICAL STORM RAFAEL DISCUSSION NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172012 1100 PM AST FRI OCT 12 2012 RAFAEL HAS A RATHER DISORGANIZED APPEARANCE IN SATELLITE IMAGERY THIS EVENING. THE BROAD LOW-LEVEL CENTER IS LOCATED TO THE WEST OF THE MAIN CONVECTIVE MASS DUE TO 20-25 KT OF SOUTHWESTERLY VERTICAL WIND SHEAR. LESS CONCENTRATED CONVECTION IS OCCURRING TO THE NORTHWEST OF THE CENTER. THERE HAVE BEEN NO OBSERVATIONS OF TROPICAL-STORM-FORCE WINDS FROM THE LESSER ANTILLES...BUT IT IS LIKELY THAT SUCH WINDS ARE LOCATED IN THE CONVECTIVE BAND EAST AND SOUTHEAST OF THE CENTER. THE INITIAL INTENSITY REMAINS 35 KT IN AGREEMENT WITH THE SATELLITE INTENSITY ESTIMATE FROM TAFB. THE INITIAL MOTION IS A RATHER UNCERTAIN 325/9. RAFAEL IS CURRENTLY SOUTHEAST OF A LARGE BREAK IN THE SUBTROPICAL RIDGE CAUSED BY TROPICAL DEPRESSION PATTY...A FRONTAL SYSTEM...AND A MID/UPPER- LEVEL TROUGH. THIS SYNOPTIC PATTERN SHOULD STEER RAFAEL GENERALLY NORTH-NORTHWESTWARD FOR THE NEXT 24-36 HR...WITH THE CENTER PASSING NEAR THE VIRGIN ISLANDS IN ABOUT 24 HOURS. THE GLOBAL MODELS FORECAST A LOW/MID-LEVEL RIDGE TO BRIEFLY BUILD NORTH OF RAFAEL AT ABOUT 48 HR...WHICH WILL SUBSEQUENTLY BREAK DOWN AS A POWERFUL DEEP-LAYER TROUGH MOVES INTO THE WESTERN ATLANTIC. THIS TROUGH SHOULD RECURVE RAFAEL INTO THE WESTERLIES. WHILE THE GLOBAL MODELS AGREE ON THIS...THEY DIFFER ENOUGH ON THE DETAILS THAT THE GFS AND CANDIAN SHOW A MUCH FASTER FORWARD MOTION AFTER RECURVATURE THAN THE ECMWF AND UKMET. THE NEW TRACK FORECAST FOLLOWS THE PREVIOUS FORECAST IN SPLITTING THE DIFFERENCE BETWEEN THESE EXTREMES. OVERALL...THE NEW FORECAST TRACK IS CLOSE TO THE OLD TRACK AND NEAR THE CENTER OF THE GUIDANCE ENVELOPE. LITTLE CHANGE IN STRENGTH IS EXPECTED DURING THE FIRST 12 HR DUE TO CONTINUED SHEAR. AFTER THAT...THE GLOBAL MODELS FORECAST A DECREASE IN SHEAR FROM 24-48 HR...WITH THE INTENSITY GUIDANCE SHOWING INTENSIFICATION DURING THIS TIME. THE INTENSITY FORECAST DURING THIS PERIOD IS NEAR THE INTENSITY CONSENSUS. THE GLOBAL MODELS AGREE ON INCREASING SHEAR AFTER 48 HR. DESPITE THIS...THE GFDL...HWRF...AND SHIP MODELS FORECAST RAFAEL TO STRENGTHEN INTO A HURRICANE. THE INTENSITY FORECAST WILL RELY MORE ON THE FORECAST SHEAR AND SHOW ARRESTED DEVELOPMENT AFTER 48 HR. EXTRATROPICAL TRANSITION SHOULD BEGIN BY 120 HR AND LIKELY BE COMPLETE SHORTLY THEREAFTER. FORECAST POSITIONS AND MAX WINDS INIT 13/0300Z 15.4N 63.4W 35 KT 40 MPH 12H 13/1200Z 16.6N 63.9W 35 KT 40 MPH 24H 14/0000Z 18.4N 64.3W 40 KT 45 MPH 36H 14/1200Z 20.3N 65.0W 50 KT 60 MPH 48H 15/0000Z 22.1N 66.1W 55 KT 65 MPH 72H 16/0000Z 26.0N 67.0W 55 KT 65 MPH 96H 17/0000Z 34.5N 63.5W 55 KT 65 MPH 120H 18/0000Z 44.5N 55.5W 50 KT 60 MPH $$ FORECASTER BEVEN