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HURRICANE JOYCE DISCUSSION NUMBER 12
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT THU SEP 28 2000
ALTHOUGH STRONG SHEAR WAS NOT ANTICIPATED...EARLY VISIBLE SATELLITE
IMAGERY INDICATES THAT THE CENTER HAS BECOME PARTIALLY EXPOSED AND
IT WAS LOCATED JUST TO THE SOUTHWEST OF VERY DEEP CONVECTION. THIS
IMPLIES SHEAR. THE ANTICYCLONIC OUTFLOW CONTINUES TO BE NONDESCRIPT
BUT THE HIGH CLOUDS ARE EMANATING RADIALLY OUTWARD. ON THE OTHER
HAND...THE AREA OF CLOUD COVERAGE IS A LITTLE LARGER THAN 24 HOURS
AGO WITH BANDING FEATURES. T-NUMBERS HAVE DECREASED SOME... SO THE
INITIAL INTENSITY HAS BEEN ADJUSTED TO 75 KNOTS. SOME FLUCTUATIONS
IN INTENSITY ARE EXPECTED DURING THE NEXT 12 TO 24 HOURS.
THEREAFTER...JOYCE IS FORECAST TO BE UNDER UPPER-LEVEL EASTERLIES OR
LIGHT SHEAR AND STRENGTHENING IS INDICATED. SHIPS AND GDFL ALSO
CALL FOR INTENSIFICATION.
AS SEVERAL MODELS INDICATED...MAINLY THE NCEP AVN AND THE
GFDL...JOYCE HAS BEEN MOVING WEST-SOUTHWEST AT ABOUT 12 KNOTS. BOTH
A STRONG WESTWARD MOVING UPPER-TROUGH OVER THE EASTERN ATLANTIC AND
A RIDGE NORTH OF JOYCE ARE FORECAST TO MOVE IN TANDEM TO THE WEST.
THIS PATTERN WOULD PROVIDE A GENERAL WESTWARD TRACK THROUGH 72
HOURS. LONGER RANGE FORECASTS SUGGEST THAT THE MID TO UPPER-LEVEL
RIDGE TO THE NORTH OF JOYCE SHOULD PERSIST BUT SOMEWHAT WEAKER
...ALLOWING THE TROPICAL CYCLONE TO MOVE ON A MORE WEST-NORTHWEST
TRACK.
A NOAA GULFSTREAM JET IS SCHEDULE TO FLY SYNOPTIC SURVEILLANCE
MISSIONS AHEAD OF JOYCE OVER THE WEEKEND TO HELP TO DETERMINE THE
FORECAST TRACK OF THIS POTENTIALLY DANGEROUS HURRICANE. A
RECONNAISSANCE PLANE WILL NOT BE IN THE AREA OF JOYCE UNTIL SUNDAY.
FORECASTER AVILA
FORECAST POSITIONS AND MAX WINDS
INITIAL 28/1500Z 11.5N 44.7W 75 KTS
12HR VT 29/0000Z 11.1N 46.1W 70 KTS
24HR VT 29/1200Z 11.0N 48.0W 80 KTS
36HR VT 30/0000Z 11.0N 50.5W 85 KTS
48HR VT 30/1200Z 11.5N 53.0W 90 KTS
72HR VT 01/1200Z 13.0N 56.5W 95 KTS
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