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HURRICANE JOYCE DISCUSSION NUMBER  14
NATIONAL WEATHER SERVICE MIAMI FL
11 PM AST THU SEP 28 2000
 
JOYCE WENT THROUGH A VERY STRONG CONVECTIVE BURST EARLIER THIS
EVENING...WITH A LARGE AREA OF CLOUD TOPS COLDER THAN -80C.  THE
TOPS ARE CURRENTLY WARMING.  SATELLITE INTENSITY ESTIMATES FROM TAFB
AND SAB REMAIN 77 KT...SO THE MAXIMUM INTENSITY REMAINS 75 KT.

THE BURST MADE THE CENTER DIFFICULT TO LOCATE...AND THE BEST
ESTIMATE OF THE MOTION IS 260/12.  INFRARED SATELLITE IMAGERY
INDICATES A LOW/MID LEVEL RIDGE NORTH OF JOYCE...WHILE WATER VAPOR
IMAGERY INDICATES A LARGE MID/UPPER LEVEL COLD LOW DEVELOPING WELL
TO THE NORTHEAST.  LARGE SCALE GUIDANCE SUGGESTS THAT THE RIDGE TO
THE NORTH WILL PERSIST TO SOME EXTENT FOR THE NEXT THREE DAYS WHILE
THE COLD LOW MOVES WESTWARD.  FORECAST TRACK GUIDANCE RESPONDS TO
THESE FEATURES BY TAKING JOYCE WEST-SOUTHWEST FOR 12-24 HR...THEN
TURNING IT TO THE WEST-NORTHWEST OR NORTHWEST.  SINCE A NORTHWEST
MOTION TAKES JOYCE TOWARD A STRONG MID/UPPER LEVEL RIDGE FORECAST TO
FORM NORTH OF PUERTO RICO...IT IS UNCERTAIN WHY THE MODELS TAKE THE
STORM SO FAR NORTH.  PERHAPS SUBSIDENCE ON THE SOUTHWEST SIDE OF THE
COLD LOW WILL INCREASE LOW/MID LEVEL RIDGING EAST OF JOYCE AND THUS
TURN IT NORTHWARD...BUT THE COLD LOW CIRCULATION DOES NOT YET EXTEND
FAR ENOUGH SOUTH TO DO THIS.  GIVEN THE UNCERTAINLY...THE FORECAST
TRACK WILL BE AN UPDATE OF THE PREVIOUS PACKAGE IN BEST AGREEMENT
WITH THE UKMET.  IT IS NOTABLE THAT THE GFDL...GFDN...NOGAPS...
AVN...LBAR...AND VICBAR ARE ALL TO THE RIGHT OF THE CURRENT
FORECAST.  THE NHC98...NHC98UK...BAMM...AND BAMD ARE TO THE RIGHT OF
THE FORECAST.

JOYCE SHOWS GOOD RADIAL OUTFLOW IN ALL DIRECTIONS...WITH SOME
EVIDENCE OF AN OUTFLOW JET TO THE EAST.  DESPITE THIS...THE CYCLONE
IS STILL SOMEWHAT DISORGANIZED FOR ITS CURRENT INTENSITY.  LARGE
SCALE MODELS HAVE DIFFERENT SOLUTIONS FOR THE UPPER LEVEL WINDS NEAR
JOYCE...WITH THE NOGAPS AND UKMET LOOKING GENERALLY FAVORABLE AND
THE AVN SOMEWHAT LESS SO.  THE PERSISTENT COLD TOPS CERTAINLY SHOW
THE POTENTIAL FOR STRENGTHENING...SO THE INTENSITY FORECAST WILL BE
SIMILAR TO THE PREVIOUS FORECAST AND A COMPROMISE BETWEEN THE
STRONGER SHIPS AND THE WEAKER GFDL.  IT IS POSSIBLE THAT JOYCE COULD
STRENGTHEN FASTER THAN CURRENTLY FORECAST IF IT EVER DEVELOPS A
WELL-DEFINED EYE.
 
THE 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 BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     29/0300Z 11.0N  47.0W    75 KTS
12HR VT     29/1200Z 10.7N  48.8W    75 KTS
24HR VT     30/0000Z 10.7N  51.1W    80 KTS
36HR VT     30/1200Z 10.9N  53.3W    85 KTS
48HR VT     01/0000Z 11.5N  55.5W    90 KTS
72HR VT     02/0000Z 13.5N  59.5W    95 KTS
 
 
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