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| #41567 (Received by flhurricane at: 4:58 AM 24.Aug.2005) TCDAT2 TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT WED AUG 24 2005 SATELLITE IMAGERY DURING THE NIGHT INDICATES THAT TROPICAL DEPRESSION TWELVE IS GRADUALLY BECOME BETTER ORGANIZED...WITH AN INCREASE IN THE CONVECTIVE BANDING OVER THE EASTERN SEMICIRCLE. REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT SHOW THAT OVERALL THE CIRCULATION IS BETTER DEFINED THAT IT WAS 12 HR AGO...ALTHOUGH THE MAXIMUM WINDS ARE 75-90 N MI EAST OF THE CENTER. THE AIRCRAFT FOUND 45 KT FLIGHT-LEVEL WINDS AT 925 MB IN THAT AREA...WHICH WOULD NORMALLY SUPPORT TROPICAL STORM SURFACE WINDS. HOWEVER...SINCE THE WINDS ARE SO FAR REMOVED FROM THE CENTER...AND NONE OF THE BAHAMAS STATIONS ARE REPORTING MORE THAN 20 KT WINDS... IT IS UNCLEAR HOW MUCH OF THE FLIGHT-LEVEL WINDS ARE REACHING THE SURFACE. THUS...THE CYCLONE REMAINS A 30 KT DEPRESSION FOR THIS ADVISORY. THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 310/6. THE DEPRESSION IS ON THE SOUTHWEST SIDE OF THE BERMUDA HIGH...WITH A WEAKNESS IN THE HIGH NEAR THE SOUTHEAST U.S. COAST. LARGE-SCALE MODELS...EXCEPT FOR THE GFS...FORECAST THE WEAKNESS TO FILL AND BE REPLACED BY A RIDGE AS A MID/UPPER-LEVEL TROUGH OVER THE NORTHEASTERN U. S. MOVES EASTWARD. THIS SHOULD CAUSE THE CYCLONE TO TURN MORE WESTWARD IN 24-48 HR...TRACKING ACROSS SOUTHERN FLORIDA INTO THE EASTERN GULF OF MEXICO. ALL TRACK GUIDANCE EXCEPT FOR THE GFS AGREES WITH THIS SCENARIO. THE GFS KEEPS A WEAKNESS IN PLACE THROUGH THE FORECAST PERIOD...AND CALLS FOR THE CYCLONE TO STALL OVER FLORIDA AND THEN MOVE NORTHWARD BY 120 HR. THE OFFICIAL FORECAST DISREGARDS THE GFS SOLUTION AND CALLS FOR THE CYCLONE TO CROSS FLORIDA INTO THE GULF. THE NEW TRACK IS AN UPDATE OF THE OLD TRACK AND IS JUST TO THE RIGHT OF THE MODEL CONSENSUS. THE INTENSITY FORECAST REMAINS PROBLEMATIC. IN THE SHORT TERM...THE BROAD NATURE OF THE SYSTEM AND A POCKET OF MID/UPPER-LEVEL DRY AIR SEEN IN WATER VAPOR IMAGERY JUST WEST OF THE SYSTEM SHOULD SLOW DEVELOPMENT. ONCE THE CYCLONE CONSOLIDATES...IT SHOULD STRENGTHEN MORE QUICKLY AS THE UPPER-LEVEL WINDS BECOME MORE FAVORABLE. THE SHIPS MODEL BRINGS THE SYSTEM TO 55-65 KT AS IT REACHES FLORIDA. ON THE OTHER HAND...THE GFDL BRINGS IT TO FLORIDA AS A DEPRESSION. THIS APPEARS UNLIKELY GIVEN THE REASONABLY FAVORABLE ENVIRONMENT ALONG THE FORECAST TRACK. THE INTENSITY FORECAST LEANS TOWARDS THE SHIPS MODEL...CALLING FOR A 60 KT INTENSITY IN 48 HR. THE CYCLONE SHOULD WEAKEN WHILE OVER FLORIDA...THE RE-INTENSIFY OVER THE EASTERN GULF OF MEXICO. A TROPICAL STORM WARNING COULD BE ISSUED FOR PORTIONS OF THE TROPICAL STORM WATCH AREA IN FLORIDA LATER TODAY... POSSIBLY INCLUDING A HURRICANE WATCH IF THE DEPRESSION STRENGTHENS MORE RAPIDLY THAN CURRENTLY FORECAST. THE UNCERTAINTY IN THIS FORECAST...AND THE POTENTIAL IMPACTS OF THIS TROPICAL CYCLONE... ARE QUANTIFIED IN AN EXPERIMENTAL NHC TEXT PRODUCT ISSUED WITH THIS AND EVERY ADVISORY PACKAGE DURING 2005. THIS PRODUCT PROVIDES WIND SPEED PROBABILITIES AT SPECIFIC LOCATIONS. THE PROBABILITIES OF EXPERIENCING TROPICAL STORM FORCE WINDS FROM THIS SYSTEM DURING THE NEXT FIVE DAYS ARE SIMILAR AT EACH INDIVIDUAL LOCATION THROUGHOUT THE TROPICAL STORM WATCH AREA. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 24/0900Z 24.0N 76.4W 30 KT 12HR VT 24/1800Z 24.7N 77.1W 40 KT 24HR VT 25/0600Z 25.5N 78.0W 45 KT 36HR VT 25/1800Z 25.9N 78.9W 50 KT 48HR VT 26/0600Z 26.1N 80.0W 60 KT 72HR VT 27/0600Z 26.5N 82.0W 40 KT...INLAND 96HR VT 28/0600Z 27.0N 84.0W 55 KT...OVER WATER 120HR VT 29/0600Z 28.0N 86.5W 65 KT |
