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TROPICAL STORM JOYCE DISCUSSION NUMBER  22
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT SAT SEP 30 2000
 
A FEW BURSTS OF DEEP CONVECTION DEVELOPED NORTH AND SOUTH OF THE
SYSTEM EARLIER...BUT HAVE SINCE WEAKENED.  SOME NEW BANDING FEATURES
MAY BE TRYING TO DEVELOP EAST AND WEST OF THE CIRCULATION CENTER AND 
THE INITIAL INTENSITY IS INCREASED TO 40 KT BASED ON A SATELLITE
INTENSITY ESTIMATE OF 45 KT FROM ALL THREE SATELLITE AGENCIES. 
HOWEVER...THE INTENSITY WAS HELD DOWN SLIGHTLY DUE TO THE OVERALL
CONVECTIVE ORGANIZATION LOOKING SOMEWHAT RAGGED.  A RECON AIRCRAFT
WILL BE OUT TO INVESTIGATE THE SYSTEM AROUND 06Z.

THE INITIAL MOTION ESTIMATE IS 285/12.  THERE IS NO SIGNIFICNAT
CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING.  THE NEW MODEL
GUIDANCE IS TIGHTLY CLUSTERED AROUND THE PREVIOUS TRACK...SO THE
OFFICIAL FORECAST TRACK IS JUST AN EXTENSION OF THE PREVIOUS
FORECAST. THE SUBTROPICAL RIDGE TO THE NORTH IS EXPECTED TO
STRENGTHEN THROUGH THE FORECAST PERIOD...WHICH SHOULD KEEP JOYCE ON
A GENERAL WEST-NORTHWEST TRACK.

ALL OF THE INTENSITY MODELS AGREE ON JOYCE STRENGTHENING IN ABOUT 
18 TO 24 HOURS.  THE PROBLEM HAS BEEN THE NORTHERLY MID-LEVEL SHEAR
THAT STILL HAS NOT LET UP.  WATER VAPOR IMAGERY INDICATES THE MID-
LEVEL NORTH AND NORTHEASTERLY FLOW IS UNDERCUTTING THE CIRRUS
OUTFLOW LAYER.  HOWEVER...THE LATEST 01/00Z UPPER-AIR OBSERVATIONS
FROM THE LESSER ANTILLES INDICATE THE MID-LEVEL FLOW IS MORE
EASTERLY... WHICH SHOULD HELP TO LESSEN THE SHEAR ONCE JOYCE REACHES
THE WINDWARD ISLANDS BY LATE SUNDAY.  THE SHIPS INTENSITY MODEL
TAKES JOYCE UP TO 83 KT IN 72 HOURS...BUT THE OFFICIAL FORECAST IS
LOWER DUE TO THE EXPECTED INCREASE IN THE UPPER-LEVEL WINDS FROM THE
EAST AT 30 KT BY 48 HOURS ACROSS THE EASTERN CARIBBEAN SEA.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     01/0300Z 10.8N  58.3W    40 KTS
12HR VT     01/1200Z 11.3N  60.1W    40 KTS
24HR VT     02/0000Z 11.9N  62.5W    45 KTS
36HR VT     02/1200Z 12.7N  65.2W    50 KTS
48HR VT     03/0000Z 13.5N  68.0W    55 KTS
72HR VT     04/0000Z 15.0N  72.5W    70 KTS
 
 
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