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TROPICAL DEPRESSION SEVEN-E DISCUSSION NUMBER   2
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT FRI AUG 06 1999

TROPICAL DEPRESSION SEVEN-E HAS CHANGED LITTLE OVER THE PAST FEW
HOURS... WITH A CONVECTIVE BAND OVER THE SOUTHWEST SEMICIRCLE AND
SOMEWHAT DISORGANIZED CONVECTIVE BURSTS NEAR THE CENTER. SATELLITE
ESTIMATES ARE 35 AND 30 KT FROM SAB AND TAFB RESPECTIVELY. BASED ON
THE CENTRAL CONVECTION...THE SYSTEM REMAINS A DEPRESSION ON THIS
PACKAGE.

THE INITIAL MOTION IS 285/15. WATER VAPOR IMAGERY INDICATES A LARGE
MID/UPPER LEVEL TROUGH COVERING THE PACIFIC NORTH OF 20N BETWEEN
110W-130W...WITH AN UPPER LOW NEAR 16N113W. THE COMBINATION OF THESE
FEATURES SUGGESTS A NORTHWEST TRACK FOR THE DEPRESSION...WHICH IS
THE NOGAPS MODEL FORECAST. HOWEVER...THE AVN MODEL BUILDS A MID
LEVEL RIDGE WESTWARD WITH THE CYCLONE...WITH AVN-BASED GUIDANCE
AND THE GFDL INDICATING A WEST-NORTHWEST MOTION. AN ADDITIONAL FLY
IN THE OINTMENT IS THE SLOW-MOVING TROPICAL LOW NEAR 12N 120W WHICH
IS GETTING BETTER ORGANIZED. THIS SYSTEM...WHICH WAS INITIALIZED TOO
FAR EAST BY BOTH THE AVN AND NOGAPS...COULD COMPLICATE THE STEERING
OF SEVEN-E IN TWO TO THREE DAYS. WITH THE LARGER THAN NORMAL
UNCERTAINTY...THE ONLY CHANGE FROM THE PREVIOUS FORECAST TRACK WILL
BE A FASTER MOTION DURING THE FIRST 36 HOURS TO REFLECT THE INITIAL
MOTION.
 
SINCE THE CENTRAL CONVECTION IS CURRENTLY DISORGANIZED...THE
INTENSIFICATION DURING THE FIRST 12-24 HOURS IS LIKELY TO BE A
LITTLE SLOWER THAN THE PREVIOUS FORECAST. THE REMAINDER OF THE
INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS PACKAGE AND THE SHIPS
MODEL. THE NOGAPS FORECASTS LESS SHEAR OVER THE CYCLONE AFTER 24
HOURS THAN THE AVN...AND IF THIS VERIFIES THE SYSTEM COULD INTENSIFY
MORE QUICKLY THAN CURRENTLY FORECAST.
 
BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     06/0900Z 12.6N 102.9W    30 KTS
12HR VT     06/1800Z 13.1N 105.1W    35 KTS
24HR VT     07/0600Z 13.9N 107.9W    45 KTS
36HR VT     07/1800Z 14.5N 110.4W    55 KTS
48HR VT     08/0600Z 15.0N 112.5W    65 KTS
72HR VT     09/0600Z 16.0N 116.5W    75 KTS
 
 
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