Tropical Storm GRACE

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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
 
 
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