ZCZC MIATCDAT5 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION TWENTY DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT SAT OCT 01 2005 AIR FORCE RECON AIRCRAFT THIS AFTERNOON FOUND A SMALL SURFACE CIRCULATION SOUTHWEST OF WHERE SATELLITE AND SURFACE OBSERVATIONS SUGGEST THE LARGER-SCALE CENTER OF ROTATION IS LOCATED. RECENT OBSERVATIONS FROM NOAA BUOY 42056 ALSO INDICATE VEERING SURFACE WINDS... WHICH SUGGESTS THAT ANOTHER SMALL-SCALE CIRCULATION MAY BE PASSING JUST SOUTHWEST OF THE BUOY. FLIGHT-LEVEL WINDS AT 850 MB SUGGEST THAT A BROADER CIRCULATION CENTER IS EITHER LOCATED OR FORMING NORTHEAST OF THE VORTEX MESSAGE POSITION. THE ADVISORY POSITION IS A COMPROMISE OF ALL THE SMALL SWIRLS AND LEANS MORE TOWARD THE LARGE-SCALE ROTATION NOTED IN SATELLITE IMAGERY AND THE SURFACE PRESSURE PATTERN. HOWEVER... ANY ONE OF THE SMALLER CIRCULATIONS COULD BECOME MORE DOMINANT IF DEEP CONVECTION DEVELOPS NEARBY. THE INITIAL INTENSITY OF 30 KT IS BASED ON A 31-KT SUSTAINED WIND REPORTED EARLIER BY NOAA BUOY 42056. THE INITIAL MOTION ESTIMATE IS AN UNCERTAIN 255/05. THE VARIOUS GLOBAL AND REGIONAL MODELS DID NOT INITIALIZE THE DEPRESSION VERY WELL... ESPECIALLY THE GFS AND CANADIAN MODELS. HOWEVER... THE GENERAL TREND IN ALL OF THE MODELS IS FOR THE BROAD SUBTROPICAL RIDGE TO THE NORTH ALONG THE NORTHERN GULF COAST TO SLOWLY BUILD WESTWARD THROUGHOUT THE FORECAST PERIOD. THE MORE WESTWARD AND SOUTHERLY INITIAL POSITION HAS RESULTED IN A SOUTHWARD SHIFT OF THE BAM MODELS... AND AS RESULT... THE OFFICIAL FORECAST TRACK WAS ALSO SHIFTED SOUTHWARD. IT SHOULD BE NOTED THAT SOME ERRATIC MOTION WILL BE POSSIBLE UNTIL A WELL-DEFINED LOW-LEVEL CENTER DEVELOPS. EXCLUDING LAND INTERACTION... ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE QUITE FAVORABLE FOR SOME SIGNIFICANT INTENSIFICATION TO OCCUR. THE SHIPS MODEL INCREASES THE INTENSITY TO 86 KT BY 72 HOURS AND 94 KT BY 96 HOURS DUE TO VERY WARM SSTS AND LOW VERTICAL SHEAR. THE 12Z GFDL MODEL LOSES THE CYCLONE BY 24 HOURS... WHICH IS NOT UNUSUAL FOR SYSTEMS THAT ARE INITIALIZED WITH 25 KT WINDS. THE 18Z GFDL WILL LIKELY BE MORE ROBUST SINCE IT WAS INITIALIZED WITH 30 KT SURFACE WINDS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 01/2100Z 19.2N 86.5W 30 KT 12HR VT 02/0600Z 19.8N 87.9W 35 KT...INLAND ERN YUCATAN 24HR VT 02/1800Z 20.4N 89.8W 25 KT...INLAND WRN YUCATAN 36HR VT 03/0600Z 21.0N 91.8W 35 KT...OVER WATER 48HR VT 03/1800Z 21.4N 93.6W 50 KT 72HR VT 04/1800Z 21.6N 96.2W 65 KT 96HR VT 05/1800Z 21.0N 99.0W 30 KT...INLAND ERN MEXICO 120HR VT 06/1800Z...DISSIPATED INLAND $$ NNNN
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Page last modified: Saturday, 01-Oct-2005 21:10:12 UTC