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| #636520 (Received by flhurricane at: 10:38 AM 05.Oct.2013) TCDAT2 TROPICAL STORM KAREN DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122013 1000 AM CDT SAT OCT 05 2013 THE LOW-LEVEL CENTER OF KAREN REMAINS EXPOSED ABOUT 100 N MI TO THE WEST-NORTHWEST OF THE DEEP CONVECTION. BASED ON SEVERAL SFMR WINDS AROUND 35 KT FROM THE EARLIER AIRCRAFT MISSIONS IN KAREN EARLY THIS MORNING...THE INITIAL INTENSITY REMAINS 35 KT. THE NEXT AIRCRAFT MISSIONS INTO KAREN THIS AFTERNOON WILL HELP DETERMINE IF THE CYCLONE HAS WEAKENED TO A DEPRESSION. THE ENVIRONMENT REMAINS UNFAVORABLE FOR INTENSIFICATION AND MOST OF THE GUIDANCE SHOWS GRADUAL WEAKENING. THE NEW NHC FORECAST SHOWS THE SYSTEM WEAKENING TO A DEPRESSION IN 24 HOURS. THERE IS LITTLE DIFFERENCE IN IMPACTS BETWEEN A 30-KT DEPRESSION AND A 35-KT TROPICAL STORM...AND TROPICAL STORM FORCE GUSTS COULD EASILY OCCUR IN CONVECTIVE BANDS. KAREN SHOULD DISSIPATE OR BE ABSORBED BY A COLD FRONT SHORTLY AFTER 48 HOURS. KAREN HAS BEEN MOVED QUICKLY NORTH-NORTHWESTWARD OVER THE PAST FEW HOURS...AND THE INITIAL POSITION IS TO THE LEFT AND AHEAD OF THE PREVIOUS FORECAST TRACK. THE INITIAL MOTION ESTIMATE IS NOW 355/07...AS KAREN HAS NOW TURNED NORTHWARD. A SHARP NORTHEASTWARD TURN IS SHOWN BY ALL OF THE GUIDANCE IN THE NEXT 24 HOURS AHEAD OF A MID/UPPER-LEVEL TROUGH...WITH AN EAST-NORTHEASTWARD MOTION AND AN INCREASE IN FORWARD SPEED EXPECTED THROUGH DISSIPATION. THE MORE NORTHERLY INITIAL POSITION RESULTS IN A NORTHWARD SHIFT OF THE NHC TRACK...WHICH NOW TAKES THE CENTER OVER SOUTHEASTERN LOUISIANA AND THEN ALONG THE GULF COAST THROUGH 36 HOURS BEFORE MOVING FARTHER INLAND. IT IS WORTH NOTING THAT THE ECMWF...WHICH HAS PERFORMED QUITE WELL WITH KAREN...TAKES A WEAKER SYSTEM ALMOST DUE EASTWARD AFTER 24 HOURS...AND THIS MOTION CANNOT BE RULED OUT IF THE CYCLONE DECOUPLES AND IS STEERED BY THE LOW-LEVEL FLOW. USERS SHOULD NOT FOCUS ON THE DETAILS OF THE TRACK FORECAST NOW THAT KAREN IS A WEAKER SYSTEM WITH THE CONVECTION WELL REMOVED FROM THE CENTER...SINCE THE TRACK OF THE CENTER WILL HAVE LESS BEARING ON WHERE THE SENSIBLE WEATHER IMPACTS WILL OCCUR. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 27.9N 91.7W 35 KT 40 MPH 12H 06/0000Z 28.7N 91.5W 35 KT 40 MPH 24H 06/1200Z 29.4N 90.3W 30 KT 35 MPH...INLAND 36H 07/0000Z 30.3N 88.1W 30 KT 35 MPH...NEAR THE COAST 48H 07/1200Z 31.3N 85.3W 25 KT 30 MPH...INLAND 72H 08/1200Z...DISSIPATED $$ FORECASTER BRENNAN |
