Tropical Depression TWELVE

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TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT THU SEP 04 2003
 
SURFACE OBSERVATIONS SHOW AN ELONGATED TROUGH EXTENDING FROM THE
DEPRESSION CENTER NORTHEASTWARD TO THE FLORIDA COAST...HOWEVER...
DATA FROM THE RECONNAISSANCE AIRCRAFT SHOWED A WELL-DEFINED
CIRCULATION.  AIRCRAFT AND SURFACE OBSERVATIONS SUGGEST THAT THE
MAXIMUM WINDS ARE NEAR 30 KT.  THE DEPRESSION IS LOCATED TO THE
NORTHWEST OF AN UPPER-LEVEL ANTICYCLONE...AND IN THIS POSITION IS
EXPERIENCING SOUTHWESTERLY SHEAR THAT SHOULD ACT TO LIMIT RAPID
STRENGTHENING.  

THE INITIAL MOTION IS 055/2.  SOME ERRATIC MOTION IS LIKELY OVER THE
NEXT DAY OR SO GIVEN THE POOR RELATIONSHIP BETWEEN THE CIRCULATION
CENTER AND THE CONVECTION.  GLOBAL MODELS MAINTAIN A WEAK
WEST-SOUTHWESTERLY STEERING FLOW OVER THE GULF AND SOUTHEASTERN
STATES OVER MUCH OF THE FORECAST PERIOD. THE OFFICIAL FORECAST IS
SIMILAR TO THE PREVIOUS ADVISORY IN CALLING FOR A SLOW EAST-
NORTHEASTWARD MOTION FOR THE NEXT THREE DAYS. AFTER THAT...RIDGING
BEHIND HURRICANE FABIAN COULD HELP KEEP THE DEPRESSION RELATIVELY
CLOSE TO THE U.S. COAST.  THE OFFICIAL FORECAST IS ADJUSTED
SLIGHTLY WESTWARD...AND REPRESENTS A BLEND OF THE GFS AND UKMET
SOLUTION. 

THERE IS A LARGE AREA OF RAIN ASSOCIATED WITH THE DEPRESSION TO THE
EAST OF THE CENTER...AND THESE RAINS ARE ALREADY AFFECTING PORTIONS
OF FLORIDA.  REGARDLESS OF WHETHER THIS SYSTEM BECOMES A TROPICAL
STORM OR NOT...IT POSES A SIGNIFICANT RAINFALL/FLOODING THREAT.
 
FORECASTER FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      04/1500Z 27.9N  87.1W    30 KT
 12HR VT     05/0000Z 28.1N  86.3W    30 KT
 24HR VT     05/1200Z 28.5N  85.0W    35 KT
 36HR VT     06/0000Z 28.9N  83.6W    40 KT
 48HR VT     06/1200Z 29.5N  82.5W    35 KT...INLAND
 72HR VT     07/1200Z 31.0N  80.0W    35 KT...OVER WATER
 96HR VT     08/1200Z 33.0N  77.0W    35 KT
120HR VT     09/1200Z 35.0N  73.0W    35 KT
 
 
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