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| #152549 (Received by flhurricane at: 10:55 AM 26.Sep.2007) TCDAT2 TROPICAL STORM KAREN DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122007 1100 AM EDT WED SEP 26 2007 KAREN CONTINUES TO SPIN UP AS A RAGGED EYE HAS BEEN SEEN INTERMEDITENTLY THIS MORNING IN VISIBLE AND INFRARED IMAGERY. SUBJECTIVE DVORAK CLASSIFICATIONS AT 12Z ARE AT 4.0 AND 3.5 FROM TAFB AND SAB...RESPECTIVELY. AN AMSU PASS AT 08Z SUGGESTED AROUND 60 KT FROM THE CIMSS TECHNIQUE. THE ADT...HOWEVER...ANALYSES KAREN A BIT WEAKER AT ABOUT 50 KT. GIVEN THE IMPROVED PRESENTATION SINCE SYNOPTIC TIME...THE INITIAL INTENSITY OF KAREN IS SET AT 60 KT. THE TROPICAL STORM IS MOVING AT 285/11 SOUTH OF A WEAK DEEP LEVEL RIDGE. AN UPPER TROUGH NORTHWEST OF KAREN IS FORECAST BY ALL MODELS TO SLOWLY RETROGRADE AND PRODUCE ENOUGH OF A WEAKNESS IN THE RIDGE TO ALLOW THE CYCLONE TO TURN TO THE NORTHWEST. THE MODEL GUIDANCE IS TIGHTLY CLUSTERED FOR THE FIRST 48 HOURS. AT DAYS 3 TO 5...MOST MODELS SLOW KAREN'S PROGRESSION AS THE STEERING FLOW SLACKENS. THE MODELS DIFFER AT THE LONG RANGE ON BOTH THE STRENGTH OF THE CYCLONE'S VORTEX AS WELL AS THE AMPLITUDE OF A SHORTWAVE TROUGH NEAR BERMUDA. THE TRACK FORECAST IS CLOSE TO THE CONSENSUS OF DYNAMICAL MODELS WITH LESS WEIGHT BEING PLACED ON THE NORTHERN OUTLYING NOGAPS MODEL. GIVEN THAT THE CYCLONE IS INTENSIFYING...IT APPEARS THAT IT MAY REACH HURRICANE INTENSITY SOON. ENVIRONMENTAL CONDITIONS ARE MIXED. SSTS ARE A WARM 28C THOUGH THE SHEAR IS ANALYZED TO BE ABOUT 15 KT OUT OF THE WEST. THIS SHEAR DOES APPEAR TO BE RESTRICTING THE WESTERN OUTFLOW OF KAREN. THE SHEAR IS PREDICTED BY ALL MODELS TO BE MAINTAINED OR EVEN GET STRONGER AT DAYS 3 TO 5 DUE TO THE INFLUENCE OF THE EARLIER MENTIONED UPPER LEVEL TROUGH. THE INTENSITY FORECAST BRINGS KAREN TO A HURRICANE SHORTLY... LEVELING OFF IN A DAY OR TWO...AND THEN WEAKENING AT DAYS 4 AND 5. THIS IS IN AGREEMENT WITH SHIPS AND LGEM BUT STRONGER THAN HWRF AND GFDL WHICH DO NOT BRING KAREN TO HURRICANE INTENSITY. FORECAST POSITIONS AND MAX WINDS INITIAL 26/1500Z 11.9N 42.9W 60 KT 12HR VT 27/0000Z 12.6N 44.5W 65 KT 24HR VT 27/1200Z 14.0N 46.8W 75 KT 36HR VT 28/0000Z 15.5N 48.5W 75 KT 48HR VT 28/1200Z 16.8N 50.0W 70 KT 72HR VT 29/1200Z 19.0N 52.0W 65 KT 96HR VT 30/1200Z 21.0N 54.0W 60 KT 120HR VT 01/1200Z 23.0N 55.5W 55 KT $$ FORECASTER LANDSEA/PASCH |
