[NCEP Logo] HOME PRODUCTS FORECASTS IMAGERY ABOUT TPC RECONNAISSANCE

ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM JOYCE DISCUSSION NUMBER  18
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT FRI SEP 29 2000
 
TROPICAL STORM JOYCE HAS CONTINUED TO WEAKEN SLIGHTLY AND THE
INITIAL INTENSITY OF 45 KT IS BASED ON A SATELLITE INTENSITY
ESTIMATE OF 45 TO 50 KT FROM ALL THREE SATELLITE AGENCIES.  THE
OUTFLOW IS FAIR TO GOOD TO THE NORTH AND POOR ELSEWHERE.
 
THE INITIAL MOTION ESTIMATE IS 270/13.  THERE HAVE BEEN SOME
FLUCTUATIONS IN THE FORWARD SPEED AND DIRECTION THE PAST 12 HOURS...
BUT THE GENERAL TREND HAS BEEN WESTWARD.  WATER VAPOR IMAGERY AND
30/00Z UPPER-AIR OBSERVATIONS INDICATE THE NORTH AND NORTHEASTERLY
MID-LEVEL SHEAR THAT HAS CAUSED JOYCE TO WEAKEN AND TRACK 
WEST-SOUTHWEST THE PAST 2 DAYS MAY BE LETTING UP.  THERE REMAINS
CONSIDERABLE DIVERGENCE AMONG THE MODEL FORECASTS WITH NOGPAPS BEING
THE FARTHEST NORTH NEAR ANTIGUA AND CLIPER BEING THE FARTHEST WEST
AND SOUTH NEAR COLOMBIA.  THE OFFICIAL FORECAST IS CLOSE TO THE
GFDL...AVN...AND GUNS MODELS...AND FASTER THAN THE PREVIOUS
FORECAST.  THIS IS SIMILAR TO BUT SLOWER THAN THE UKMET MODEL WHICH
TAKES JOYCE FASTER AND INTO THE CENTRAL CARIBBEAN IN 72 HOURS.

THE INTENSITY FORECAST IS LESS STRAIGHTFORWARD.  AS LONG AS JOYCE
REMAINS IN A SHEARING ENVIRONMENT...LITTLE IF ANY INTENSIFICATION
SHOULD OCCUR.  HOWEVER...BY 24 HOURS...ALL OF THE GLOBAL MODELS
AGREE ON THE AFOREMENTIONED MID-LEVEL SHEAR DECREASING SIGNIFICANTLY
AS THE DEEP MID-OCEANIC TROUGH TO THE NORTHEAST OF JOYCE WEAKENS AND
PULLS AWAY TO THE NORTH AND NORTHEAST.  JOYCE HAS A VERY DEEP AND
WELL-ORGANIZED VERTICAL CIRCULATION...GIVEN THAT JOYCE HAS SURVIVED
SOME VERY HOSTILE SHEAR CONDITIONS THE PAST 2 DAYS.  AS A
RESULT...RE-INTENSIFICATION TO HURRICANE INTENSITY COULD OCCUR
QUICKLY ONCE THE SHEAR LETS UP ON THE CYCLONE.  THE OFFICIAL
FORECAST IS SIMILAR TO THE SHIPS INTENSITY MODEL...WHICH BRINGS
JOYCE TO 82 KT IN 72 HOURS.
 
SINCE JOYCE IS FORECAST TO BE A STRONG TROPICAL STORM JUST SOUTHEAST
OF BARBADOS IN 36 HOURS...A TROPICAL STORM OR HURRICANE WATCH MAY BE
ISSUED FOR BARBADOS BY SATURDAY MORNING.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     30/0300Z 10.5N  53.0W    45 KTS
12HR VT     30/1200Z 10.8N  54.5W    45 KTS
24HR VT     01/0000Z 11.7N  57.0W    50 KTS
36HR VT     01/1200Z 12.8N  59.2W    55 KTS
48HR VT     02/0000Z 13.8N  61.2W    65 KTS
72HR VT     03/0000Z 16.0N  65.0W    80 KTS
  
NNNN


Problems?