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| #112711 (Received by flhurricane at: 4:37 AM 24.Sep.2006) TCDAT3 HURRICANE HELENE DISCUSSION NUMBER 49 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082006 500 AM EDT SUN SEP 24 2006 HELENE CONTINUES TO MAINTAIN DEEP CONVECTION NEAR THE CENTER...ALTHOUGH THERE IS LESS OF IT NOW THAN 6 HOURS AGO. THE INITIAL INTENSITY WILL REMAIN 75 KT BASED ON THE EARIER QUIKSCAT DATA. OVER THE NEXT 24 HOURS...HELENE WILL BE MOVING OVER COOLER WATERS AND THE VERTICAL SHEAR IS EXPECTED TO INCREASE. HOWEVER...INTERACTION WITH A SHORT-WAVE TROUGH IN THE WESTERLIES APPROACHING HELENE COULD KEEP THE WINDS UP...SO LITTLE CHANGE IN INTENSITY IS SHOWN UNTIL AFTER 24 HOURS...WHEN THE BAROCLINIC FORCING IS EXPECTED TO DIMINISH. HELENE IS EXPECTED TO LOSE TROPICAL CHARACTERISTICS AS IT IS OVERTAKEN BY THE SHORT-WAVE TROUGH IN ANOTHER 12 TO 24 HOURS...IF IT HASN'T ALREADY LOST IT'S DEEP CONVECTION BY THEN. MODEL GUIDANCE IS IN VERY GOOD AGREEMENT NOW ON A CONTINUED EAST-NORTHEASTWARD MOTION...WITH ONLY THE ECMWF DROPPING HELENE SOUTHWARD NEAR THE AZORES. MUCH OF THE GUIDANCE SUGGESTS A SLOWING OF THE TRACK IN ABOUT 24 HOURS AS MID-LATITUDE SHORT WAVE ENERGY DROPS SOUTH OF HELENE...WEAKENING THE STEERING CURRENT. THE OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS ADVISORY AND TO A TIGHTLY-CLUSTERED GFS/GFDL/UKMET/NOGAPS CONSENSUS. FORECAST POSITIONS AND MAX WINDS INITIAL 24/0900Z 39.9N 39.9W 75 KT 12HR VT 24/1800Z 41.6N 36.6W 70 KT...EXTRATROPICAL 24HR VT 25/0600Z 43.2N 33.1W 65 KT...EXTRATROPICAL 36HR VT 25/1800Z 44.5N 30.0W 60 KT...EXTRATROPICAL 48HR VT 26/0600Z 45.0N 26.0W 50 KT...EXTRATROPICAL 72HR VT 27/0600Z 47.0N 18.0W 45 KT...EXTRATROPICAL 96HR VT 28/0600Z...ABSORBED $$ FORECASTER FRANKLIN |
