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TROPICAL DEPRESSION FOUR-E DISCUSSION NUMBER   2
NATIONAL WEATHER SERVICE MIAMI FL
2 PM PDT TUE JUL 09 2002
 
TROPICAL DEPRESSION FOUR-E HAS CHANGED LITTLE DURING THE DAY. 
MODERATE UPPER-LEVEL WESTERLY SHEAR HAS RESULTED IN MAINLY BRIEF 
PULSES OF DEEP CONVECTION NEAR THE PARTIALLY EXPOSED LOW-LEVEL 
CENTER. HOWEVER...INNER-CORE BANDING FEATURES HAVE IMPROVED DURING 
THE LAST 3 HOURS. THE INITIAL INTENSITY OF 30 KT IS BASED ON DVORAK 
SATELLITE INTENSITY ESTIMATES OF 30 KT AND 35 KT FROM TAFB AND 
SAB...RESPECTIVELY. 
 
THE INITIAL MOTION ESTIMATE IS 285/12. THE DEPRESSION IS EXPECTED TO
CONTINUE MOVING WEST-NORTHWEST OR WESTWARD UNDER THE INFLUENCE OF 
THE STRONG SUBTROPICAL RIDGE THAT EXTENDS FROM MEXICO NORTHWARD INTO 
THE SOUTHWEST UNITED STATES. THE 18Z NHC MODEL GUIDANCE IS MORE 
TIGHTLY CLUSTERED THAN THE PREVIOUS RUNS...EXCEPT FOR THE AVN MODEL 
WHICH HAS MADE A SIGNIFICANT DROP TO THE SOUTH AND IS NOW THE 
LEFTMOST MODEL. THIS MAY BE DUE TO ITS FARTHER SOUTH INITIALIZATION. 
THE GFDL IS CONSISTENT WITH ITS PREVIOUS FORECAST TRACK AND IS 
ALMOST ON TOP OF THE PREVIOUS OFFICIAL FORECAST. AS SUCH...I HAVE 
NOT MADE ANY SIGNIFICANT CHANGES TO THE PREVIOUS FORECAST TRACK.
 
SLOW INTENSIFICATION IS FORECAST FOR THE NEXT 24 HOURS OR SO
OWING TO MODERATE UPPER-LEVEL WESTERLY SHEAR. AS THE DEPRESSION 
MOVES FARTHER WEST...THE UPPER-LEVEL WINDS ARE FORECAST TO WEAKEN 
AND EVEN BECOME SLIGHTLY ANTICYCLONIC. THIS SHOULD ALLOW FOR MORE 
SIGNIFICANT INTENSIFICATION IN THE LATTER PERIODS. THE 12Z GFDL 
MODEL HAS CONTINUED ITS TREND OF BRINGING THE CYCLONE UP TO 115 KT 
IN 66 HOURS...BUT ONLY BRINGS THE SYSTEM UP TO 83 KT IN 60 HOURS 
WHICH SEEMS MORE REASONABLE AT THIS TIME. THE SHIPS MODEL TAKES THE 
CYCLONE UP TO 76 KT IN 72 HOURS...WHILE THE EXPERIMENTAL CHIPS MODEL 
HAS 98 KT IN 72 HOURS. A CONSENSUS FORECAST THAT IS SLIGHTLY HIGHER 
THAN SHIPS WAS FOLLOWED GIVEN THE PRESENT SHEAR PATTERN.
 
FORECASTER STEWART
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     09/2100Z 12.1N 102.2W    30 KTS
12HR VT     10/0600Z 12.4N 104.0W    35 KTS
24HR VT     10/1800Z 12.7N 106.4W    40 KTS
36HR VT     11/0600Z 13.2N 108.3W    50 KTS
48HR VT     11/1800Z 13.9N 110.1W    65 KTS
72HR VT     12/1800Z 15.5N 113.0W    85 KTS
 
 
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