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| #9247 (Received by flhurricane at: 10:46 AM 19.Sep.2004) TCDAT1 TROPICAL STORM JEANNE DISCUSSION NUMBER 24 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 AM EDT SUN SEP 19 2004 HIGH RESOLUTION VISIBLE SATELLITE IMAGES DEFINITELY SHOW THAT THE LOW-LEVEL CIRCULATION HAS BECOME LARGE AND BETTER ORGANIZED. THERE ARE CYCLONICALLY-CURVED CONVECTIVE BANDS WRAPPING AROUND THE SYSTEM AND THE OUTFLOW IS WELL-ESTABLISHED. HOWEVER...JEANNE LACKS AN INNER CORE WHICH IS NORMALLY ASSOCIATED WITH A STRONGER CYCLONE. THEREFORE THE INITIAL INTENSITY IS KEPT AT 40 KNOTS. A RECONNAISSANCE PLANE WILL CHECK JEANNE LATER TODAY. GIVEN THE CURRENT CONDITIONS OF LOW SHEAR AND THE LARGE CIRCULATION...SOME STRENGTHENING IS INDICATED. HOWEVER...GLOBAL MODELS SUGGEST THAT VERY HOSTILE WESTERLY WINDS SHOULD BEGIN TO APPROACH JEANNE IN A COUPLE OF DAYS. THEREFORE...THE INTENSITY IS INCREASED ONLY TO 65 KNOTS IN THE FORECAST WHICH MAY BE GENEROUS. THE LARGE CIRCULATION APPEARS TO BE MOVING NORTHWARD AT ABOUT 4 KNOTS AROUND THE SUBTROPICAL HIGH AND AHEAD OF A MID-LEVEL TROUGH. THERE IS CONFIDENCE THAT THIS GENERAL MOTION WILL LIKELY CONTINUE DURING THE NEXT DAY OR TWO. HOWEVER...IN ABOUT 3 DAYS THE STEERING CURRENTS WILL WEAKEN AND JEANNE IS FORECAST TO MEANDER BETWEEN BERMUDA AND THE BAHAMAS FOR THE REST OF THE FORECAST PERIOD. IN THE LONG RANGE...THE FORECAST IS HIGHLY UNCERTAIN. FOR EXAMPLE...RECENT RUNS OF THE GFS HAVE BEEN ALTERNATING BETWEEN AN EASTWARD AND A WESTWARD TRACK...AND SOLUTIONS FROM THE OTHER GLOBAL MODELS HAVE NOT BEEN ANY MORE CONCLUSIVE. THE LATEST FIVE DAY FORECAST POINTS OF THE UKMET AND GFS MODELS ARE ABOUT 1200 N MI APART. IN SUCH CASES...THE BEST OPTION IS TO KEEP THE CYCLONE MEANDERING IN BETWEEN THE TWO EQUALLY VALID MODEL OPTIONS. FORECASTER AVILA FORECAST POSITIONS AND MAX WINDS INITIAL 19/1500Z 23.5N 72.5W 40 KT 12HR VT 20/0000Z 24.8N 72.5W 45 KT 24HR VT 20/1200Z 26.5N 71.5W 50 KT 36HR VT 21/0000Z 27.5N 70.5W 55 KT 48HR VT 21/1200Z 27.5N 70.0W 60 KT 72HR VT 22/1200Z 26.5N 70.0W 65 KT 96HR VT 23/1200Z 26.0N 70.5W 65 KT 120HR VT 24/1200Z 26.0N 71.5W 65 KT |
