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| #110779 (Received by flhurricane at: 5:03 AM 14.Sep.2006) TCDAT2 HURRICANE GORDON DISCUSSION NUMBER 14 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072006 500 AM EDT THU SEP 14 2006 ALTHOUGH GORDON'S EYE REMAINS DISTINCT...IT HAS BECOME SMALLER AND A LITTLE LESS WELL-DEFINED IN THE LAST FEW HOURS. THE INITIAL INTENSITY OF 105 KT IS A BLEND OF SUBJECTIVE T-NUMBERS FROM SAB AND TAFB OF 5.5. THE OUTFLOW IN THE WESTERN SEMICIRCLE HAS DIMINISHED IN THE LAST FEW HOURS...AS CLOUD-TRACKED WINDS SUGGEST THAT SOUTHWESTERLY FLOW AHEAD OF AN UPPER-LEVEL LOW TO THE WEST OF GORDON IS IMPINGING ON THE CYCLONE. THESE TRENDS SUGGEST GORDON MAY BE PEAKING IN INTENSITY...AND THE INTENSITY GUIDANCE SHOWS A GRADUAL WEAKENING IN THE NEXT COUPLE OF DAYS. THE INTENSITY FORECAST IS A BLEND OF THE GFDL AND SHIPS THROUGH DAY 2 AND LEANS MORE TOWARD THE GFDL AFTER THAT TIME...AS SHIPS SEEMS TO WEAKEN THE CYCLONE TOO QUICKLY LATE IN THE PERIOD. THE CURRENT MOTION IS 030/11 AS GORDON CONTINUES TO ROUND THE WESTERN PERIPHERY OF THE ATLANTIC SUBTROPICAL RIDGE. MOST OF THE DYNAMICAL MODELS ARE IN AGREEMENT THAT GORDON WILL SLOW CONSIDERABLY IN THE 2-3 DAY TIME PERIOD AS THE CYCLONE IS LEFT IN AN AREA OF WEAK FLOW NORTH OF THE RIDGE AND SOUTH OF THE WESTERLIES. THEREAFTER...AN EXTRATROPICAL CYCLONE IS FORECAST BY THE GLOBAL MODELS TO MOVE FROM THE CAROLINAS INTO THE WESTERN ATLANTIC EAST OF THE MID-LEVEL TROUGH DIGGING INTO EASTERN UNITED STATES. THE INTERACTION OF GORDON WITH THESE FEATURES VARIES AMONG THE DYNAMICAL MODELS...AS THE GFS...THE GFS ENSEMBLE MEAN...AND THE ECMWF SHOW GORDON BEING ABSORBED INTO THE EXTRATROPICAL CYCLONE BY DAY 4 OR 5. CONVERSELY...THE NOGAPS...GFDL...AND UKMET KEEP GORDON AS A DISTINCT SYSTEM THROUGH THE PERIOD...CONSISTENT WITH THE STRONGER INITIAL DEPICTION OF GORDON IN THESE MODELS. IF THE FIRST SCENARIO PLAYS OUT...IT IS UNLIKELY THAT GORDON WOULD UNDERGO EXTRATROPICAL TRANSITION...SINCE IT WOULD REMAIN SOUTH OF THE MAIN BAROCLINIC ZONE BEFORE ABSORPTION. HOWEVER...IF GORDON REMAINS INTACT IT WOULD LIKELY BEGIN EXTRATROPICAL TRANSITION LATE IN THE PERIOD AS IT MOVES NORTHEAST AHEAD OF THE MID-LATITUDE TROUGH. AT THIS POINT...IT IS TOO EARLY TO DETERMINE WITH MUCH CERTAINLY WHICH OF THESE SCENARIOS IS MORE LIKELY TO OCCUR. HOWEVER...THE CURRENT FORECAST ASSUMES GORDON WILL REMAIN A SEPARATE SYSTEM AND BEGIN EXTRATROPICAL TRANSITION TOWARD THE END OF THE PERIOD. THE TRACK FORECAST IS A BLEND OF THE DYNAMICAL MODEL CONSENSUS AND IS VERY CLOSE TO THE FSU SUPERENSEMBLE AND THE PREVIOUS ADVISORY. FORECAST POSITIONS AND MAX WINDS INITIAL 14/0900Z 28.7N 56.6W 105 KT 12HR VT 14/1800Z 30.1N 55.6W 105 KT 24HR VT 15/0600Z 31.4N 54.5W 90 KT 36HR VT 15/1800Z 32.3N 53.7W 80 KT 48HR VT 16/0600Z 32.8N 53.2W 70 KT 72HR VT 17/0600Z 34.5N 51.0W 65 KT 96HR VT 18/0600Z 38.0N 46.0W 50 KT 120HR VT 19/0600Z 42.0N 37.0W 50 KT...EXTRATROPICAL $$ FORECASTER BRENNAN/KNABB |
