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| #9844 (Received by flhurricane at: 4:54 AM 24.Sep.2004) TCDAT1 HURRICANE JEANNE DISCUSSION NUMBER 43 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT FRI SEP 24 2004 THE INTENSITY OF JEANNE IS A BIT OF A PUZZLE THIS MORNING. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT MEASURED A CENTRAL PRESSURE OF 969 MB...WHICH WOULD NORMALLY SUPPORT WINDS OF NEAR 90 KT. HOWEVER...THE MAXIMUM FLIGHT-LEVEL WINDS REPORTED BY THE AIRCRAFT AT 700 MB WERE ONLY 74 KT...WHICH WOULD SUPPORT CLOSER TO 65 KT SURFACE WINDS. POST-ECLIPSE SATELLITE IMAGES SHOW SOME COOLING OF THE CLOUD TOPS OVER THE SOUTH QUADRANT...BUT ALSO SHOW A MUCH LESS DEFINED EYE. BASED MAINLY ON THE CENTRAL PRESSURE...THE INITIAL INTENSITY IS SET TO 85 KT. HOWEVER...THIS MAY BE GENEROUS. THE INITIAL MOTION IS NOW 270/7. WATER VAPOR IMAGERY SHOWS THAT A DEEP-LAYER ANTICYCLONE OVER THE EASTERN UNITED STATES IS NOW CENTERED NEAR THE DELMARVA PENINSULA. LARGE-SCALE MODELS INDICATE THIS SYSTEM WILL CONTINUE TO SHIFT TO THE SOUTHEAST AND ELONGATE SOUTHWARD WITH TIME. THIS PATTERN EVOLUTION SHOULD KEEP JEANNE ON A GENERAL WESTWARD COURSE FOR 36-48 HR...FOLLOWED BY A TURN TOWARD THE NORTHWEST AND EVENTUAL RECURVATURE INTO THE WESTERLIES. THE TIMING OF THE TURN IS STILL IN QUESTION...AS THE GFDL HAS SHIFTED FAR ENOUGH TO THE EAST TO MISS THE FLORIDA COAST...WHILE THE NOGAPS DRIVES JEANNE ACROSS SOUTHERN FLORIDA TO THE GULF OF MEXICO BEFORE RECURVATURE. THE OTHER DYNAMICAL MODELS ARE BETWEEN THESE TWO EXTREMES. THE OFFICIAL FORECAST TRACK KEEPS JEANNE ON THE LEFT SIDE OF THE GUIDANCE DURING THE FIRST 36-48 HR...AS THE RIDGE TO THE NORTH MAY NOT ALLOW AS MUCH NORTHWARD MOTION AS SHOWN BY THE GFDL AND GFS. AFTER THAT...THE TRACK FOLLOWS THE MODEL CONSENSUS. IT SHOULD BE NOTED THAT THE UKMET AGAIN APPEARS TO BE TOO FAST IN THE FIRST 12 HR. THE AIRCRAFT DATA INDICATES THAT JEANNE CURRENTLY HAS A BROAD WIND FIELD...WITH A RADIUS OF MAXIMUM WINDS OF 35-45 NM. BETWEEN THAT AND THE COLD UPWELLING WATER THE HURRICANE IS CURRENTLY OVER... LITTLE CHANGE IN STRENGTH IS LIKELY FOR 12 HR OR SO. BEYOND THAT TIME...JEANNE SHOULD MOVE OVER 82F WATER AND REACH 83-84F WATER BY 36 HR. THIS COULD ALLOW FOR MORE SIGNIFICANT STRENGTHENING IF THE STORM STRUCTURE HAS REORGANIZED BY THAT TIME...AND THE INTENSITY FORECAST CALLS FOR JEANNE TO REACH 100 KT INTENSITY IN 48 HR. THIS IS SLIGHTLY HIGHER THAN BOTH SHIPS AND THE GFDL. AFTER 48 HR...A COMBINATION OF INCREASING SOUTHWESTERLY VERTICAL SHEAR AND LAND INTERACTION SHOULD PRODUCE STEADY WEAKENING. THE FORECAST TRACK AND WIND RADII REQUIRE A HURRICANE WARNING FOR THE NORTHWESTERN BAHAMAS...A TROPICAL STORM WARNING FOR THE CENTRAL BAHAMAS...AND A HURRICANE WATCH FOR PORTIONS OF THE FLORIDA EAST COAST AT THIS TIME. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 24/0900Z 26.1N 71.6W 85 KT 12HR VT 24/1800Z 26.1N 73.1W 85 KT 24HR VT 25/0600Z 26.2N 75.4W 90 KT 36HR VT 25/1800Z 26.6N 77.6W 95 KT 48HR VT 26/0600Z 27.1N 79.5W 100 KT 72HR VT 27/0600Z 30.0N 81.5W 80 KT...INLAND 96HR VT 28/0600Z 34.0N 78.5W 50 KT...INLAND 120HR VT 29/0600Z 39.5N 69.5W 35 KT...OVER WATER |
