ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM GRACE DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT SAT AUG 30 2003 SATELLITE IMAGERY...BUOY AND SHIP OBSERVATIONS...ALONG WITH REPORTS FROM AN AIR FORCE RECONNAISSANCE AIRCRAFT INDICATE THAT TD-11 HAS STRENGTHENED INTO TROPICAL STORM GRACE. THE MAXIMUM 1500 FT FLIGHT-LEVEL WIND REPORTED SO FAR HAS BEEN 43 KT...WHICH EQUATES TO ABOUT 34 KT AT THE SURFACE. THERE HAVE ALSO BEEN SOME SHIP AND OIL PLATFORM WIND REPORTS OF TROPICAL STORM FORCE WINDS WELL TO THE NORTHEAST OF THE BROAD CENTER. UPPER-LEVEL OUTFLOW IS GOOD IN THE EASTERN SEMICIRCLE...BUT RESTRICTED TO THE WEST. THE INITIAL MOTION ESTIMATE IS A RATHER SHAKY 300/09. RECON HAS HAD DIFFICULTY PINPOINTING THE BROAD CENTER...ALTHOUGH BUOY AND RECON WINDS CLEARLY SHOW A CLOSED A CIRCULATION. THERE ARE SOME INDICATIONS FROM SATELLITE AND THE RECON WIND REPORTS THAT THE CENTER MAY BE EVEN FARTHER SOUTH THAN WHAT IS INDICATED IN THIS ADVISORY. IF THE CENTER DOES FORM FARTHER SOUTH...THEN LANDFALL WILL BE DELAYED BY AT LEAST ANOTHER 6 HOURS OR MORE THAN WHAT THE CURRENT FORECAST INDICATES. THE BAM MODELS ARE TIGHTLY PACKED ABOUT A SLOWER AND MORE WESTWARD TRACK NEAR CORPUS CHRISTI TEXAS... WHILE THE GFS...NOGAPS...GFDL...AND ETA MODELS ARE CLOSER TO THE SOUTHERN END OF GALVESTON ISLAND. THE OFFICIAL FORECAST TRACK IS JUST A TAD TO THE LEFT OF THE PREVIOUS TRACK AND A LITTLE SLOWER... AND IS BETWEEN THE TIGHTLY PACKED BAM MODELS AND THE GFS...NOGAPS...ETA ...AND GFDL CONSENSUS. THIS KEEPS GRACE OFFSHORE THROUGH 24 HOURS. THE GLOBAL AND REGIONAL MODELS ALL AGREE ON THE UPPER-LEVEL LOW LOCATED NEAR BROWNSVILLE TEXAS TO SHIFT WESTWARD AND WEAKEN. THIS ALLOWS THE 200 MB FLOW TO WEAKEN...BACK AROUND TO THE SOUTHEAST... AND BECOME DIFLUENT ACROSS THE CYCLONE. THIS UPPER-FLOW PATTERN... COMBINED WITH 29C AND WARMER SSTS...IS FAVORABLE FOR ADDITIONAL STRENGTHENING TO OCCUR. THE OFFICIAL INTENSITY FORECAST IS CLOSE TO THE SHIPS INTENSITY MODEL...WHICH BRINGS GRACE TO 57 KT IN 24 HOURS. IF GRACE REMAINS FARTHER SOUTH AND MOVES SLOWER THAN WHAT IS FORECAST...THEN A LITTLE MORE STRENGTHENING COULD OCCUR. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 30/2100Z 25.6N 93.7W 35 KT 12HR VT 31/0600Z 26.5N 94.9W 45 KT 24HR VT 31/1800Z 28.0N 96.1W 55 KT 36HR VT 01/0600Z 29.7N 97.5W 30 KT...DISSIPATING INLAND 48HR VT 01/1800Z 30.9N 99.1W 20 KT...DISSIPATING INLAND 72HR VT 02/1800Z...DISSIPATED INLAND NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:57 UTC