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TROPICAL STORM DEBBY DISCUSSION NUMBER  18
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT WED AUG 23 2000

DEBBY WAS HARD HIT BY SOUTHWESTERLY VERTICAL WIND SHEAR AND THE HIGH
MOUNTAINS OF HISPANIOLA.   SATELLITE IMAGES DEPICT A VERY ILL-
DEFINED LOW CLOUD CENTER WITH ONLY A FEW CELLS OF DEEP CONVECTION.
SURFACE OBSERVATIONS SHOW A BROAD AREA OF LOW PRESSURE OF ABOUT 1008
MB OVER THE WINDWARD PASSAGE.  A RECONNAISSANCE PLANE IS EN ROUTE TO
DETERMINE IF A CLOSED CIRCULATION STILL EXITS. 

BASED ON EARLIER RECON REPORTS OF 50 KNOTS AT FLIGHT LEVEL TO THE
NORTH OF THE ESTIMATED CENTER...THE INITIAL INTENSITY IS 40 KNOTS AT
THIS TIME.  DEBBY...OR ITS REMNANTS...SHOULD SPREAD OVER THE HIGH
TERRAIN OF EASTERN CUBA DURING THE NEXT 12 HOURS.  THEREFORE DEBBY
IS FORECAST TO BECOME A TROPICAL DEPRESSION.  IF THE CENTER
SURVIVES...AND MOVES WESTWARD OVER THE WARM WATERS SOUTH OF
CUBA...AND DECREASES IN FORWARD SPEED...IT COULD REGAIN TROPICAL
STORM INTENSITY BY 36 HOURS AS THE SHEAR DECREASES.  INTENSITY
GUIDANCE CONTINUES TO SHOW STRENGTHENING.  HOWEVER...SO FAR NONE OF
THE NUMERICAL MODELS HAVE BEEN ABLE TO PRODUCE A REALISTIC INTENSITY
FORECAST FOR DEBBY. 

THE TROPICAL STORM HAS BECOME A SHALLOW SYSTEM AND IS BEING STEERED
BY THE LOW-LEVEL FLOW.  GLOBAL MODELS KEEP A STRONG HIGH PRESSURE
SYSTEM TO THE NORTH OF DEBBY AND THIS PATTERN WOULD FAVOR A GENERAL
WESTWARD TRACK DURING THE NEXT 24 TO 36 HOURS.  THEREAFTER...A
DEVELOPING TROUGH OVER THE GULF OF MEXICO WILL WEAKEN THE HIGH
FORCING THE TROPICAL CYCLONE ON A MORE NORTHWESTERLY TRACK.  THIS IS
THE SOLUTION PROVIDED BY MOST OF THE TRACK GUIDANCE. 
 
FORECASTER AVILA
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     24/0300Z 20.0N  74.0W    40 KTS
12HR VT     24/1200Z 20.0N  76.0W    30 KTS
24HR VT     25/0000Z 20.5N  78.0W    30 KTS
36HR VT     25/1200Z 21.5N  80.0W    35 KTS
48HR VT     26/0000Z 23.0N  81.5W    35 KTS
72HR VT     27/0000Z 26.0N  83.5W    50 KTS
 
 
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