ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM GRACE DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT SAT AUG 30 2003 AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT INVESTIGATED GRACE THIS EVENING AND FOUND A VERY POORLY DEFINED CENTER NEAR BUOY 42002 AND WINDS OF ABOUT 40 KNOTS TO THE NORTHEAST OF THE CENTER AT 1500 FT FLIGHT LEVEL. SATELLITE IMAGERY SHOWS A NORTH-SOUTH ELONGATED AREA OF CONVECTION OVER THE WESTERN GULF. THIS SYSTEM IS MORE OF A NORTH-SOUTH TROUGH AS PRESSURES ABOUT 150 N MI NORTH OF THE CENTER ARE ABOUT THE SAME AS IN THE CENTER...1009 MB. THIS SYSTEM CAN ONLY BE DESCRIBED AS POORLY ORGANIZED AND IT TAKES QUITE A STRETCH TO CALL IT A TROPICAL CYCLONE. HAVING SAID THAT...THE INITIAL MOTION ESTIMATE IS 295/9 BASED ON THE AIRCRAFT CENTER POSITION AT 22Z WHICH WAS VERY NEAR BUOY 42002. THE WIND AT THIS BUOY WENT TO SOUTH AT 10 KNOTS AT 02Z SO PERHAPS THE CENTER OR TROUGH AXIS HAS GONE BY. A MID-LEVEL SUBTROPICAL RIDGE EXTENDS WESTWARD ACROSS THE SOUTHERN UNITED STATES WITH A WEAKNESS OVER TEXAS. THE GFS...NOGAPS AND GFDL RESPOND TO THIS SETUP WITH A NORTHWESTWARD TRACK FOR 24 HOURS FOLLOWED BY A SLIGHT TURN TOWARD THE WEST-NORTHWEST. THE OFFICIAL FORECAST FOLLOWS THIS GUIDANCE AND IS SHIFTED SOUTH OF THE PREVIOUS ADVISORY BASED MAINLY ON THE RECON FIX. SINCE ALL OF THE TROPICAL STORM FORCE WINDS AND HEAVY RAINFALL ARE WELL NORTH AND NORTHEAST OF THE CENTER...THIS SHIFT IN TRACK DOES NOT REQUIRE ANY CHANGE TO THE WARNING AREA. THE INITIAL INTENSITY IS 35 KNOTS BASED ON THE AIRCRAFT DATA ALONG WITH A SHIP REPORT OF 36 KNOTS AT 00Z ABOUT 180 N MI NORTHEAST OF THE CENTER. THE SHIPS MODEL BRINGS THE WIND TO 52 KNOTS IN 24 HOURS...JUST BEFORE LANDFALL. HOWEVER SHIPS THINKS THAT THAT GRACE IS A TROPICAL CYCLONE. THE GFDL...NOGAPS...UKMET AND GFS MODELS SHOW NO INTENSIFICATION WHICH IS PROBABLY A BETTER FORECAST. UNABLE TO PUT MY MONEY WHERE MY MOUTH IS...I AM FORECASTING 50 KNOTS IN 24 HOURS...BACKING OFF ONLY 5 KNOTS FROM THE PREVIOUS FORECAST. FORECASTER LAWRENCE FORECAST POSITIONS AND MAX WINDS INITIAL 31/0300Z 25.5N 94.5W 35 KT 12HR VT 31/1200Z 26.4N 95.5W 40 KT 24HR VT 01/0000Z 27.8N 96.9W 50 KT 36HR VT 01/1200Z 28.6N 98.4W 25 KT...DISSIPATING INLAND 48HR VT 02/0000Z 29.2N 100.0W 20 KT...DISSIPATING INLAND 72HR VT 03/0000Z...DISSIPATED NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:57 UTC