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TROPICAL DEPRESSION FOUR-E DISCUSSION NUMBER   1
NATIONAL WEATHER SERVICE MIAMI FL
8 AM PDT TUE JUL 09 2002
 
SATELLITE IMAGERY THIS MORNING SUGGESTS THAT THE TROPICAL
DISTURBANCE LOCATED ABOUT 325 NMI SOUTH OF ACAPULCO MEXICO HAS
DEVELOPED INTO THE FOURTH TROPICAL DEPRESSION OF THE SEASON. THE
INITIAL INTENSITY OF 30 KT IS BASED ON A DVORAK SATELLITE INTENSITY
ESTIMATE OF 30 KT FROM BOTH TAFB AND SAB. OUTFLOW IS RESTRICTED TO
THE EASTERN SEMICIRCLE DUE TO MODERATE UPPER-LEVEL WESTERLY SHEAR.
 
THE INITIAL MOTION ESTIMATE IS 285/11. THE DEPRESSION IS EXPECTED TO 
MOVE WEST-NORTHWESTWARD UNDER THE INFLUENCE OF THE MEXICAN 
SUBTROPICAL RIDGE TO THE NORTH. THE NHC MODEL GUIDANCE IS TIGHTLY 
CLUSTERED ABOUT THIS GENERAL MOTION THROUGH 48 HOURS AND THEN 
DIVERGES AFTER THAT. THE 06Z NOGAPS MODEL IS THE RIGHTMOST OF ALL 
THE MODELS...MAINLY BECAUSE IT INITIALIZED THE SYSTEM ABOUT 1.5 
DEGREES TOO FAR NORTH. THE OFFICIAL FORECAST TRACK IS CLOSER TO THE 
SLOWER AVN AND GFDL CONSENSUS.

ONLY SLOW INTENSIFICATION IS EXPECTED FOR THE NEXT 24 HOURS OR SO 
DUE TO MODERATE UPPER-LEVEL WESTERLY SHEAR. THE UPPER-LEVEL LOW OVER 
THE BAY OF CAMPECHE THAT IS CREATING THE SHEAR CONDITIONS IS 
EXPECTED TO MOVE SLOWLY EASTWARD AND WEAKEN WHILE THE DEPRESSION 
MOVES WESTWARD. AS THE TWO SYSTEMS BECOME MORE SEPARATED...THE 
UPPER-LEVEL SHEAR SHOULD DECREASE AND ALLOW FOR MORE SIGNIFICANT 
INTENSIFICATION IN THE LATTER FORECAST PERIODS. THE 06Z GFDL MODEL 
RUN BRINGS THE CYCLONE UP TO 115 KT IN 72 HOURS.  WHILE THIS IS 
CERTAINLY POSSIBLE...THE OFFICIAL INTENSITY WILL REMAIN ON THE 
CONSERVATIVE SIDE UNTIL THE UPPER-LEVEL SHEAR SHOWS SOME SIGNS OF 
DECREASING. THE SHIPS INTENSITY FORECAST MODEL ONLY BRINGS THE 
SYSTEM UP TO 74 KT IN 72 HOURS...BUT THIS IS DUE TO THE MODEL USING 
THE FASTER LBAR MODEL...WHICH TRACKS THE CYCLONE OVER COOLER WATER 
SOONER THAN THE OFFICIAL FORECAST TRACK IS INDICATING.
 
FORECASTER STEWART
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     09/1500Z 11.5N 100.8W    30 KTS
12HR VT     10/0000Z 11.9N 102.3W    35 KTS
24HR VT     10/1200Z 12.3N 104.2W    40 KTS
36HR VT     11/0000Z 12.7N 106.2W    50 KTS
48HR VT     11/1200Z 13.5N 108.5W    60 KTS
72HR VT     12/1200Z 15.0N 112.0W    80 KTS
 
 
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