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TROPICAL DEPRESSION THIRTEEN-E DISCUSSION NUMBER   4
NATIONAL WEATHER SERVICE MIAMI FL
8 AM PDT FRI SEP 01 2000
 
A SIZEABLE CONVECTIVE BURST DEVELOPED OVER THE CENTER OF TROPICAL
DEPRESSION 13-E NEAR 08Z...BUT IS NOW DECREASING IN INTENSITY AS
EASTERLY VERTICAL SHEAR CONTINUES OVER THE SYSTEM.  SATELLITE
INTENSITY ESTIMATES ARE ALL 30 KT...SO THAT WILL BE THE INITIAL
INTENSITY ON THIS ADVISORY.

THE INITIAL MOTION IS NEARLY STATIONARY.  SATELLITE IMAGERY SHOWS
LOW/MID LEVEL RIDGING AND MID/UPPER LEVEL TROUGHING NORTH OF THE
CYCLONE.  THIS COMBINATION IS CURRENTLY PRODUCING SLOW AND ERRATIC
MOTION.  LARGE-SCALE MODELS INDICATE THAT WHILE THE UPPER LEVEL
FEATURE SHOULD WEAKEN WITH TIME...SOME TROUGHING WILL CONTINUE
NORTH OR NORTHWEST OF THE DEPRESSION THROUGH THE FORECAST PERIOD. 
THIS SHOULD ALLOW A SLOW WEST-NORTHWESTWARD MOTION TO BEGIN.  TRACK
GUIDANCE IS SOMEWHAT DIVERGENT...WITH MODELS SUCH AS LBAR...BAMD...
GFDL...AND BAMM CALLING FOR A MORE NORTHWARD MOTION WHILE THE
NOGAPS AND THE UKMET CALL FOR A MORE WESTWARD MOTION.  WITH THE
CURRENT LACK OF MOTION...THE OFFICIAL FORECAST IS ALMOST IDENTICAL
TO THE PREVIOUS FORECAST AND IS VERY SIMILAR TO THE GUNS ENSEMBLE. 
THE AVN MODEL SUGGESTS THE POSSIBILITY OF INTERACTION WITH TROPICAL
DEPRESSION JOHN TO THE NORTHWEST...WHICH COULD COMPLICATE THE
MOTION.  AT THIS TIME THE FORECAST ASSUMES THIS WILL NOT HAPPEN.

THE CYCLONE REMAINS OVER WARM WATER AND IN A LIGHT TO MODERATE
EASTERLY SHEAR ENVIRONMENT JUST SOUTH OF AN UPPER LEVEL RIDGE AXIS. 
THUS...STRENGTHENING COULD OCCUR IF THE CONVECTION WERE MORE
PERSISTENT NEAR THE CENTER.  THE INTENSITY FORECAST ASSUMES THIS
WILL HAPPEN AND CALLS FOR MODEST STRENGTHENING OVER THE NEXT 24-36
HR.  AFTER THAT TIME...THE CYCLONE SHOULD TRACK INTO GRADUALLY
COOLER WATER WHICH SHOULD STOP INTENSIFICATION.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     01/1500Z 14.0N 133.2W    30 KTS
12HR VT     02/0000Z 14.3N 133.7W    35 KTS
24HR VT     02/1200Z 14.7N 134.2W    40 KTS
36HR VT     03/0000Z 15.2N 135.0W    45 KTS
48HR VT     03/1200Z 16.0N 136.0W    45 KTS
72HR VT     04/1200Z 17.5N 138.0W    45 KTS
 
 
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