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TROPICAL DEPRESSION SEVEN DISCUSSION NUMBER   4
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT WED SEP 16 1998
 
DEEP CONVECTION NEAR THE CENTER OF TROPICAL DEPRESSION SEVEN...
WHICH HAD BEEN WANING EARLIER THIS MORNING...HAS MADE A COMEBACK 
PER THE LAST INFRARED SATELLITE IMAGES. DVORAK INTENSITY ESTIMATES 
FROM TAFB AND SAB REMAIN 2.0 AND THE INITIAL INTENSITY WILL BE 
HELD AT 30 KNOTS.
 
THE SYSTEM HAS A LARGE ENVELOPE AND REMAINS FAIRLY WELL ORGANIZED. 
RECENT SATELLITE PICTURES INDICATE THE DEVELOPMENT OF A BANDING
FEATURE SOUTHWEST OF THE CENTER.  THE OUTFLOW IS BECOMING BETTER
ESTABLISHED OVER THE WESTERN PORTION OF THE DEPRESSION WHILE STILL
RESTRICTED TO THE EAST.  WITH SUFFICIENTLY WARM SST/S...28C...AND
ANALYSES FROM THE COOPERATIVE INSTITUTE FOR METEOROLOGICAL SATELLITE
STUDIES AT THE UNIVERSITY OF WISCONSIN SHOWING A LIGHT VERTICAL
SHEAR ENVIRONMENT AHEAD CONDITIONS APPEAR FAVORABLE FOR CONTINUED
DEVELOPMENT.  THUS...GRADUAL STRENGTHENING IS FORECAST IN ACCORDANCE
WITH THE PREVIOUS ADVISORY AND THE STATISTICAL HURRICANE INTENSITY
PREDICTION SCHEME...SHIPS. THIS BRINGS THE TROPICAL CYCLONE TO
HURRICANE STATUS BY 72 HOURS.
 
THE DEPRESSION CONTINUES TO MOVE WESTWARD AT A FAIRLY GOOD CLIP WITH
AN INITIAL MOTION ESTIMATE OF 275/16 KNOTS.  THE MID-LEVEL RIDGE
NORTH OF THE DEPRESSION SHOULD CONTINUE TO STEER THE SYSTEM ON A
GENERAL WESTWARD HEADING THROUGH THE 72 HOURS AS THE WESTERLIES
ASSOCIATED WITH THE LARGE-SCALE TROUGH OVER THE CENTRAL ATLANTIC
REMAIN NORTH OF 25N...PER THE 00Z AVIATION MODEL OUTPUT. MEANWHILE 
THE NAVY NOGAPS MODEL HAS THE TROUGH SLIGHTLY DEEPER RESULTING IN A
WEAKER RIDGE AND A MORE WEST-NORTHWESTERLY TRACK.  ITS INTERESTING
TO NOTE THAT THE 00Z UNITED KINGDOM MET OFFICE MODEL LOSES THE
SYSTEM AFTER 24 HOURS WHEREAS THE 15/12Z RUN HELD ON TO THE SYSTEM
THROUGH 72 HOURS.  MOST OF THE 06Z TRACK MODEL GUIDANCE IS CLUSTERED
AROUND A GENERAL WESTWARD HEADING.  THE OFFICIAL FORECAST TRACK IS
IN THE MIDDLE OF THE CLUSTER AND IS IN CLOSE AGREEMENT WITH THE
GFDL.  THIS REPRESENTS A VERY SLIGHT LEFT ADJUSTMENT FROM THE
PREVIOUS FORECAST PRIMARILY DUE TO THE INITIAL POSITION ESTIMATE. 

GUINEY
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     16/0900Z 10.2N  30.3W    30 KTS
12HR VT     16/1800Z 10.3N  32.7W    35 KTS
24HR VT     17/0600Z 10.6N  35.9W    40 KTS
36HR VT     17/1800Z 11.3N  38.9W    45 KTS
48HR VT     18/0600Z 12.0N  42.0W    55 KTS
72HR VT     19/0600Z 13.0N  47.0W    65 KTS
 
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