000 WTNT42 KNHC 150854 TCDAT2 TROPICAL STORM RAFAEL DISCUSSION NUMBER 11 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172012 500 AM AST MON OCT 15 2012 THE CONVECTIVE CLOUD PATTERN OF RAFAEL HAS CONTINUED TO IMPROVE AND A LARGE CDO FEATURE HAS NOW DEVELOPED OVER THE LOW-LEVEL CENTER. SATELLITE INTENSITY ESTIMATES ARE T4.0/65 KT FROM TAFB...T3.5/55 KT FROM SAB...AND ADT ESTIMATES ARE T3.4/53 KT...BUT WITH RAW DATA T-NUMBERS OF T4.3/72 KT. ALTHOUGH IT IS ENTIRELY POSSIBLE THAT RAFAEL COULD ALREADY BE A HURRICANE BASED ON A CONSENSUS OF THIS DATA...THE INITIAL INTENSITY IS BEING MAINTAINED AT 60 KT FOR THIS ADVISORY. AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT WILL BE INVESTIGATING RAFAEL AROUND 1200 UTC...AND DATA FROM THAT MISSION WILL PROVIDE A BETTER ESTIMATE OF THE ACTUAL INTENSITY. THE INITIAL MOTION ESTIMATE IS 335/09 KT. THERE REMAINS NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING... AND THE NHC MODEL GUIDANCE REMAINS TIGHTLY CLUSTERED THROUGH THE 72 HOUR FORECAST PERIOD. RAFAEL IS EXPECTED TO TURN NORTHWARD BY THIS AFTERNOON OR EVENING AS THE RIDGE TO THE NORTH AND NORTHEAST OF THE CYCLONE WEAKENS DUE TO AN APPROACHING DEEP-LAYER TROUGH CURRENTLY MOVING THROUGH THE EASTERN UNITED STATES. AS THE TROUGH MOVES OFF THE U.S. COAST ON TUESDAY...RAFAEL SHOULD TURN NORTHEASTWARD AND ACCELERATE. AFTER 72 HOURS...THERE IS GREATER SPREAD IN THE GUIDANCE AS SOME OF THE GLOBAL MODELS SHOW THE EXTRATROPICAL CYCLONE SLOWING DOWN AS IT INTERACTS WITH A LARGER LOW OVER THE NORTH ATLANTIC. DESPITE THESE SPEED DIFFERENCES...THE MODELS ARE IN GOOD AGREEMENT ON THEN EXTRATROPICAL RAFAEL TURNING EASTWARD OVER THE COLD WATERS OF THE FAR NORTH ATLANTIC AND POSSIBLY BECOME ABSORBED BY A LARGER EXTRATROPICAL LOW PRESSURE SYSTEM. THE OFFICIAL TRACK FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY TRACK...AND IS CLOSE TO THE TVCA CONSENSUS MODEL. DESPITE THE 21 KT OF SHEAR ASSESSED BY THE GFS-BASED SHIPS MODEL... THE UPPER-LEVEL OUTFLOW PATTERN HAS CONTINUED TO EXPAND AND IMPROVE...ESPECIALLY TO THE EAST WHERE THE OUTFLOW IS BEING ENHANCED BY A HIGHLY AMPLIFIED UPPER-LEVEL TROUGH LOCATED ALONG 40W LONGITUDE. THERE ARE CURRENTLY NO SIGNS THAT THE VERTICAL SHEAR WILL INCREASE WITHIN THE NEXT 12 HOURS...SO AT LEAST SOME GRADUAL INTENSIFICATION IS EXPECTED IN THE SHORT TERM. BY DAYS 2-3... HOWEVER...THE SHEAR IS EXPECTED TO INCREASE TO MORE THAN 30 KT AS THE U.S. DEEP-LAYER TROUGH APPROACHES RAFAEL...WHICH SHOULD INDUCE GRADUAL WEAKENING. BY DAY 4...THE GLOBAL MODELS ARE FORECASTING RAFAEL TO UNDERGO EXTRATROPICAL TRANSITION AS THE CYCLONE INTERACTS WITH A COLD FRONT. THE INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY...AND FOLLOWS THE ICON INTENSITY CONSENSUS MODEL. SPECIAL THANKS TO THE AIR FORCE RESERVE HURRICANE HUNTERS WHO PULLED DOUBLE DUTY YESTERDAY BY HELPING LOCATE A LIGHT AIRCRAFT AND ITS PASSENGERS THAT WENT DOWN NEAR THE VIRGIN ISLANDS. WELL DONE. FORECAST POSITIONS AND MAX WINDS INIT 15/0900Z 22.5N 65.3W 60 KT 70 MPH 12H 15/1800Z 23.9N 65.7W 65 KT 75 MPH 24H 16/0600Z 26.3N 65.3W 70 KT 80 MPH 36H 16/1800Z 29.6N 63.8W 70 KT 80 MPH 48H 17/0600Z 33.8N 60.9W 65 KT 75 MPH 72H 18/0600Z 42.6N 50.6W 60 KT 70 MPH 96H 19/0600Z 48.2N 35.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 20/0600Z 49.3N 24.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ FORECASTER STEWART