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#30569 (Received by flhurricane at: 11:00 PM 06.Jul.2005) TCDAT4 HURRICANE DENNIS DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT WED JUL 06 2005 DENNIS HAS FINALLY MIXED OUT THE DRY AIR THAT HAD WRAPPED INTO THE CENTER DURING THE DAY. AIR FORCE RESERVE AND NOAA HURRICANE HUNTER AIRCRAFT HAVE BEEN FLYING INTO DENNIS THIS AFTERNOON AND EVENING... AND REPORTS INDICATE SURFACE WINDS HAVE LIKELY INCREASED TO AT LEAST 75 KT AND THE PRESSURE HAS DECREASED TO AT LEAST 980 MB...A PRESSURE DROP OF 7 MB IN THE PAST 5 HOURS. A CDO FEATURE HAS ALSO DEVELOPED OVER THE CENTER IN SATELLITE IMAGERY...AND A WARM SPOT/PRE-EYE FEATURE HAS BEEN TRYING TO DEVELOP THE PAST COUPLE OF HOURS. HOWEVER...AN EARLIER SSMI MICROWAVE OVERPASS INDICATED A CLOSED EYE HAD ALREADY DEVELOPED IN THE MID-LEVELS. THE INITIAL MOTION ESTIMATE IS 300/13. THERE ARE NO CHANGES TO PREVIOUS TRACK FORECAST OR REASONING. THE MODELS REMAIN IN STRONG AGREEMENT THAT THE SUBTROPICAL RIDGE CURRENTLY EXTENDING EAST-WEST ACROSS THE FLORIDA PENINSULA WILL REMAIN INTACT THROUGH 60-72 HOURS. THIS SHOULD KEEP DENNIS MOVING WEST-NORTHWESTWARD THROUGH 72 HOURS. AFTER THAT...HOWEVER... THE MODELS VARY SIGNIFICANTLY ON HOW THE MID-LATITUDE FLOW PATTERN EVOLVES ACROSS THE CENTRAL AND WESTERN U.S....WHICH ULTIMATELY HAS AN IMPACT ON THE STEERING FLOW OVER THE GULF OF MEXICO. HALF OF THE MODELS BUILD A HIGH AMPLITUDE RIDGE OVER THE GREAT LAKES AND SOUTHWESTWARD INTO THE SOUTHERN PLAINS...WHILE THE OTHER MODELS LIKE THE NAM...CANADIAN...GFDL... AND NOGAPS HAVE LESS RIDGING AND MORE TROUGHING OVER THE WESTERN AND CENTRAL GULF. OVERALL...THE MODEL GUIDANCE HAS SHIFTED SLIGHTLY TO THE RIGHT. GIVEN THIS UNCERTAINTY IN THE LONGER RANGE...THE OFFICIAL FORECAST TRACK IS JUST AN EXTENSION OF THE PREVIOUS TRACK. NOW THAT A CDO AND EYE HAVE DEVELOPED...THE ONLY INHIBITING FACTOR WOULD BE INTERACTION WITH LAND. IN THE ABSENCE OF THAT...THE LOW SHEAR AND 29C SSTS FAVOR SIGNIFICANT INTENSIFICATION FOR AT LEAST THE NEXT 48 HOURS. THE LATEST GFDL MODEL RUN BRINGS DENNIS TO 127 KT IN 36 HOURS...WHILE THE SHIPS MODEL IS FAIRLY ROBUST IN TAKING DENNIS UP TO 107 KT IN 60 HOURS. ALL OF THE MODELS AGREE THAT SOME SOUTHWESTERLY SHEAR COULD AFFECT THE HURRICANE JUST PRIOR TO MAKING LANDFALL...SO SLIGHT WEAKENING IS INDICATED AT 96 HOURS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 07/0300Z 16.5N 73.4W 75 KT 12HR VT 07/1200Z 17.6N 75.4W 85 KT 24HR VT 08/0000Z 19.2N 77.8W 95 KT 36HR VT 08/1200Z 20.7N 80.1W 105 KT 48HR VT 09/0000Z 22.2N 82.1W 105 KT 72HR VT 10/0000Z 25.0N 85.0W 105 KT 96HR VT 11/0000Z 28.5N 87.0W 100 KT 120HR VT 12/0000Z 32.0N 88.5W 80 KT...INLAND |