Tropical Storm GRACE

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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
 
 
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