[NCEP Logo] HOME ARCHIVES FORECASTS IMAGERY ABOUT TPC RECONNAISSANCE

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TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER   6
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT SUN SEP 22 2002

THE DEPRESSION IS SLOWLY GETTING BETTER ORGANIZED.  THE LOW LEVEL
CENTER APPEARS TO BE BENEATH THE MASS OF CONVECTION THAT HAS
PERSISTED FOR THE PAST FEW HOURS.  THE INITIAL INTENSITY FOR THIS
ADVISORY REMAINS 30 KNOTS AS WE WAIT TO SEE IF THE CONVECTION
PERSISTS A BIT LONGER AROUND THE LOW LEVEL CENTER...AND TO SEE WHAT
THE RECONNAISSANCE AIRCRAFT FINDS IN THE MORNING.

INITIAL MOTION REMAINS WESTWARD...275 AT 20 KNOTS.  NUMERICAL
GUIDANCE IS SPLIT INTO TWO CAMPS.  GFS AND GFDL TAKE THE CYCLONE DUE
WESTWARD THROUGH 72 HOURS...WHILE UKMET AND NOGAPS ARE ON THE RIGHT
EDGE OF THE GUIDANCE ENVELOPE WITH A MORE NORTHWESTWARD TRACK.  THE
OFFICIAL FORECAST CLOSELY FOLLOWS THE CONSENSUS OF THESE FOUR MODELS
AND IS SLIGHTLY TO THE LEFT OF THE PREVIOUS ADVISORY TRACK...AND A
BIT SLOWER BEYOND 48 HOURS DUE TO A WEAKNESS IN THE RIDGE TO THE
NORTH...ASSOCIATED WITH TROPICAL STORM KYLE.

THE WEAK TROUGH CURRENTLY SEEN IN WATER VAPOR IMAGERY OVER THE
LESSER ANTILLES IS EXPECTED TO MOVE WEST AND ALLOW AN ANTICYCLONE TO
BUILD OVER THE TROPICAL CYCLONE.  AS A RESULT...THE WEAK
SOUTHEASTERLY SHEAR CURRENTLY IMPACTING THE SYSTEM IS FORECAST TO
SLACKEN FURTHER AND REMAIN WEAK WHEN THE SYSTEM TRACKS OVER THE
WARMER WATERS OF THE EASTERN CARIBBEAN.  THEREFORE...THE OFFICIAL
FORECAST INDICATES GRADUAL INTENSIFICATION BEGINNING IN ABOUT 24
HOURS.  THIS FORECAST IS CONSISTENT WITH THE PREVIOUS ADVISORY AND
IS IN CLOSE AGREEMENT WITH THE SHIPS MODEL.

FORECASTER JARVINEN/KNABB
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     23/0300Z 12.2N  56.0W    30 KTS
12HR VT     23/1200Z 12.6N  58.9W    30 KTS
24HR VT     24/0000Z 13.4N  62.4W    35 KTS
36HR VT     24/1200Z 14.1N  65.4W    50 KTS
48HR VT     25/0000Z 15.0N  67.7W    55 KTS
72HR VT     26/0000Z 16.0N  70.5W    65 KTS
 
 
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