HOME	ACTIVE CYCLONES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

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TROPICAL DEPRESSION FOUR DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
10 AM EST FRI AUG 20 1999
 
MORNING VISIBLE IMAGERY INDICATES THE CENTER OF TROPICAL DEPRESSION
FOUR IS EXPOSED AT THE NORTHEASTERN EDGE OF THE POORLY ORGANIZED
CONVECTION. ALTHOUGH THE LATEST SATELLITE INTENSITY ESTIMATES REMAIN
AT TROPICAL STORM INTENSITY...THE SYSTEM REMAINS A DEPRESSION ON
THIS PACKAGE DUE TO THE RAGGED APPEARANCE AND NO IMPROVEMENT IN THE
SATELLITE SIGNATURE SINCE YESTERDAY.

THE INITIAL MOTION IS 270/8. THE AVN MODEL KEEPS A LOW LEVEL RIDGE
NORTH OF THE CYCLONE THROUGH 72 HOURS...WITH A MID/UPPER LEVEL
TROUGH DEVELOPING OVER THE RIDGE NORTH OF THE DEPRESSION. THE MODEL
AND AVN-BASED GUIDANCE RESPOND TO THE TROUGH BY TURNING THE SYSTEM
WEST-NORTHWEST. THE OFFICIAL FORECAST INCLUDES SUCH A TURN AFTER 48
HOURS...BUT NOT AS QUICKLY OR AS FAR NORTH AS THE AVN-BASED
GUIDANCE.

THE AVN AND NOGAPS SUGGEST THE PERSISTENT EASTERLY SHEAR WILL SLOWLY
DECREASE DURING THE FORECAST PERIOD...ALTHOUGH THE SHIPS MODEL STILL
HAS 22 KT SHEAR AT 48 HOURS. THE INTENSITY FORECAST CALLS FOR
GRADUAL STRENGTHENING THROUGH THE PERIOD AS THE SHEAR DECREASES.
 
BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     20/1500Z 13.8N  25.5W    30 KTS
12HR VT     21/0000Z 13.8N  26.9W    30 KTS
24HR VT     21/1200Z 14.0N  28.9W    35 KTS
36HR VT     22/0000Z 14.4N  31.2W    40 KTS
48HR VT     22/1200Z 15.0N  33.5W    45 KTS
72HR VT     23/1200Z 16.5N  38.5W    55 KTS
 
 
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