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TROPICAL STORM JOYCE DISCUSSION NUMBER   5
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT TUE SEP 26 2000

DEEP CONVECTION IS STILL LIMITED...BUT THE OVERALL CLOUD PATTERN
ASSOCIATED WITH JOYCE IS GRADUALLY IMPROVING.  THERE ARE PLENTY OF
CURVED BANDS...TYPICAL OF A DEVELOPING TROPICAL STORM...AND THE
OUTFLOW IS GOOD.  T-NUMBERS HAVE INCREASED TO 3.0 FROM BOTH TAFB AND
SAB.  CONSEQUENTLY...INITIAL INTENSITY HAS BEEN ADJUSTED TO 45
KNOTS.  DESPITE THE CURRENT UPWARD INTENSITY TREND AND THE APPARENT
FAVORABLE ENVIRONMENT OF WARM OCEAN AND LOW SHEAR AHEAD...AT LEAST
THROUGH 72 HOURS...SHIPS AND GFDL INTENSITY FORECASTS ARE ABOUT 77
AND 70 KNOTS ONLY.  THE OFFICIAL FORECAST IS CLOSE TO SHIPS AND
MAKES JOYCE A HURRICANE IN A DAY OR TWO.

A STRONG MID-LEVEL RIDGE OF HIGH PRESSURE BUILDING TO THE NORTH OF
JOYCE IS FORCING THE TROPICAL CYCLONE ON A WESTWARD TRACK ABOUT 12
KNOTS. THE RIDGE IS FORECAST TO BE SO STRONG THAT SOME OF THE MODELS
HAVE A TRACK SOUTH OF DUE WEST DURING THE NEXT 24 TO 48 HOURS. THE
FARTHER SOUTH OF DUE WEST THE TROPICAL CYCLONE MOVES...THE MORE
DANGEROUS IT COULD BECOME FOR THE LESSER ANTILLES.  HOWEVER...MOST
GLOBAL MODELS AS WELL AS THE GFDL FORECASTS AT LONGER RANGE...OR
BEYOND 72 HOURS...INDICATE A TURN TO THE WEST-NORTHWEST AND
NORTHWEST BEFORE REACHING THE LESSER ANTILLES.  THE ONLY LONG RANGE
MODEL WHICH SUGGESTS A TRACK ENTERING THE CARIBBEAN IS THE UK MODEL
BUT ONLY AS A TROUGH.  WE MUST EMPHASIZE THAT FORECASTS BEYOND 72
HOURS ARE SUBJECT TO LARGE ERRORS.

FORECASTER AVILA
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     26/2100Z 11.6N  36.1W    45 KTS
12HR VT     27/0600Z 11.5N  38.0W    50 KTS
24HR VT     27/1800Z 11.5N  40.5W    55 KTS
36HR VT     28/0600Z 11.5N  42.4W    65 KTS
48HR VT     28/1800Z 11.5N  44.5W    70 KTS
72HR VT     29/1800Z 11.5N  48.5W    75 KTS
 
 
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