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| #6163 (Received by flhurricane at: 4:40 PM 26.Aug.2004) TCDAT1 HURRICANE FRANCES DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT THU AUG 26 2004 FRANCES HAS CONTINUED TO BECOME BETTER ORGANIZED WITH A SMALL 10-15 NMI DIAMETER BANDING EYE FEATURE OCCASIONALLY APPEARING. SATELLITE INTENSITY IS T4.0...OR 65 KT...FROM BOTH TAFB AND SAB...AND THE TREND OF GOING SLIGHTLY HIGHER THAN THE SATELLITE ESTIMATES ARE INDICATING IS BEING CONTINUED ON THIS ADVISORY. UPPER-LEVEL OUTFLOW IS GOOD TO EXCELLENT IN ALL QUADRANTS AND CONTINUES TO IMPROVE. THE INITIAL MOTION IS 295/14. FRANCES HAS REMAINED ON TRACK AND THE MAJORITY OF THE NHC MODEL GUIDANCE IS IN MUCH BETTER AGREEMENT NOW ...EXCEPT FOR THE NOGAPS MODEL...WHICH APPEARS TO BE A SHARP RIGHT-OF-TRACK OUTLIER. IN FACT...THE LATEST UKMET RUN HAS SHIFTED MUCH FARTHER WEST WHILE THE GFS HAS SHIFTED A LITTLE TO THE RIGHT. THOSE TWO MODELS...PLUS THE GFDL...HAVE NOW CONVERGED ON TOP OF THE PREVIOUS FORECAST TRACK THROUGH 72 HOURS AND THEN ONLY DIVERGE SLIGHTLY AWAY FROM THE 12Z TRACK AFTER THAT. WATER VAPOR IMAGERY SUGGESTS THE CANADIAN MARITIMES LOW APPEARS TO HAVE BOTTOMED OUT AND IS SHIFTING SLOWLY EASTWARD...SO ONLY A SLIGHT WEAKENING OF THE SUBTROPICAL RIDGE TO THE NORTH OF FRANCES IS EXPECTED IN THE 36-72H TIME PERIOD. AFTERWARDS...ALL OF THE GLOBAL MODELS...EVEN NOGAPS... IS FORECASTING THE MID-LATITUDE FLOW ACROSS THE NORTHERN U.S. AND THE NORTH ATLANTIC TO BECOME STRONGLY ZONAL. WITH SUCH STRONG WESTERLY HIGH-LATITUDE FLOW BECOMING ESTABLISHED...A CORRESPONDING RESPONSE SHOULD BE A STRENGTHENING OF THE BERMUDA-AZORES RIDGE WESTWARD TO PERHAPS THE U.S. EAST COAST BY 120 HOURS. THAT PATTERN SHOULD HELP TO TURN FRANCES MORE WESTWARD AFTER 96 HOURS. AS SUCH ...THE FORECAST TRACK IS JUST AN EXTENSION OF THE PREVIOUS TRACK. SINCE FRANCES APPEARS TO HAVE MIXED OUT ANY DRY AIR INTRUSIONS...HAS A RATHER SMALL EYE...AND GOOD OUTFLOW ESTABLISHED...THEN ADDITIONAL RAPID INTENSIFICATION SEEMS LIKELY FOR AT LEAST ANOTHER 12 HOURS OR SO. AFTER THAT...THE INTENSIFICATION TREND IS LEVELED SINCE AT LEAST ONE CONCENTRIC EYEWALL CYCLE SHOULD OCCUR IN THE NEXT 72 HOURS DUE TO THE CURRENT SMALL DIAMETER EYE. TIMING ANY ADDITIONAL EYEWALL CYCLES WITH ANY KIND OF SKILL JUST IS NOT POSSIBLE...BUT SOME ADDITIONAL STRENGTHENING MAY STILL OCCUR SINCE THE HURRICANE WILL BE PASSING OVER 29C SSTS...ABOUT 1C ABOVE AVERAGE...BY 96HR. THE INTENSITY FORECAST IS A BLEND OF THE SHIPS AND GFDL MODELS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 26/2100Z 13.7N 46.4W 70 KT 12HR VT 27/0600Z 14.6N 48.1W 85 KT 24HR VT 27/1800Z 15.8N 50.2W 95 KT 36HR VT 28/0600Z 16.9N 51.7W 100 KT 48HR VT 28/1800Z 17.8N 52.8W 100 KT 72HR VT 29/1800Z 19.0N 55.0W 105 KT 96HR VT 30/1800Z 20.5N 58.5W 105 KT 120HR VT 31/1800Z 21.5N 62.5W 105 KT |
