ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM HURRICANE FRANCES DISCUSSION NUMBER 26 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT TUE AUG 31 2004 SATELLITE AND AIRCRAFT DATA INDICATE THAT FRANCES IS COMPLETING A CONCENTRIC EYEWALL CYCLE. THE AIR FORCE RESERVE HURRICANE HUNTER REPORTS A 30-40 NM DIAMETER OUTER EYEWALL WITH MAXIMUM FLIGHT-LEVEL WINDS OF 121 KT AT 700 MB...ALONG WITH A CENTRAL PRESSURE OF 949 MB. SATELLITE IMAGERY SHOWS THE REMAINS OF THE EARLIER INNER EYEWALL ARE STILL PRESENT. BASED ON THE AIRCRAFT DATA...THE MAXIMUM INTENSITY REMAINS 110 KT. THE AIRCRAFT ALSO SHOWS A WIND MAXIMA OUTSIDE OF THE OUTER EYEWALL. THE INITIAL MOTION IS NOW 280/13. FRANCES REMAINS ON THE SOUTH SIDE OF A STRONG RIDGE OVER THE WESTERN ATLANTIC. LARGE-SCALE MODELS ALL FORECAST THE RIDGE TO WEAKEN DURING THE FORECAST PERIOD...BUT THERE ARE SIGNIFICANT DIFFERENCES IN THE DETAILS WHICH HAVE MAJOR IMPLICATIONS FOR WHERE FRANCES WILL END UP. DATA FROM THE RECENT SYNOPTIC SURVEILLANCE MISSION HAD SOME INTERESTING EFFECTS ON THE DYNAMICAL MODELS. THE GFS...WHICH HAS BEEN A LEFT OUTLIER MOST OF THE TIME...HAS SHIFTED WELL TO THE RIGHT AND IS NOW A RIGHT OUTLIER...MOVING FRANCES NORTHWARD ALONG 77-78W AFTER 72 HR. THE NOGAPS...WHICH HAS BEEN A RIGHT OUTLIER...IS NOW A LEFT OUTLIER CALLING FOR LANDFALL IN SOUTHEASTERN FLORIDA. THE GFDL AND UKMET HAVE BOTH SHIFTED THEIR TRACKS TO THE RIGHT AFTER 72 HR. GIVEN THE LARGE CHANGES IN JUST ONE CYCLE...THE OFFICIAL FORECAST WILL NOT CHANGE MUCH AT ALL...BASICALLY BEING AN UPDATE OF THE PREVIOUS PACKAGE. IT IS DOWN THE CENTER OF THE MODEL GUIDANCE UP TO 72 HR AND ALONG THE LEFT SIDE THEREAFTER. WHEN THE CONCENTRIC EYEWALL CYCLE IS FINALLY DONE...FRANCES SHOULD STRENGTHEN AS INDICATED BY THE SHIPS AND GFDL MODELS. IT WOULD NOT BE A SURPRISE TO SEE MORE STRENGTHENING THAN CURRENTLY FORECAST. ALTHOUGH NOT CURRENTLY REFLECTED IN THE INTENSITY FORECAST DUE TO THE UNCERTAINTY IN THE UPPER-LEVEL WIND PATTERNS...THE SHIPS... GFDL...AND GFS MODELS SUGGEST CONDITIONS MAY BECOME LESS FAVORABLE AFTER ABOUT 48 HR. ALSO...THERE REMAINS THE POSSIBILITY OF OTHER CONCENTRIC EYEWALL CYCLES THAT CANNOT CURRENTLY BE FORECAST. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 31/0900Z 19.9N 62.8W 110 KT 12HR VT 31/1800Z 20.4N 65.0W 115 KT 24HR VT 01/0600Z 21.3N 67.7W 120 KT 36HR VT 01/1800Z 22.2N 70.2W 120 KT 48HR VT 02/0600Z 23.2N 72.3W 120 KT 72HR VT 03/0600Z 25.0N 75.5W 120 KT 96HR VT 04/0600Z 26.5N 78.5W 120 KT 120HR VT 05/0600Z 28.5N 81.5W 85 KT...INLAND $$ NNNN
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Page last modified: Tuesday, 31-Aug-2004 08:42:45 UTC