HOME	ACTIVE CYCLONES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM ARLENE DISCUSSION NUMBER   8
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT SUN JUN 13 1999

VISIBLE SATELLITE IMAGERY INDICATES THAT THE TROPICAL STORM IS BEING
INFLUENCED BY VERTICAL SHEAR...WITH THE LOW-LEVEL CIRCULATION CENTER
LOCATED NEAR THE NORTHWEST EDGE OF THE DENSE OVERCAST.  HOWEVER...
THERE ARE FAIRLY WELL-DEFINED BANDING FEATURES OVER THE EASTERN
SEMICIRCLE.  ANALYSES FROM THE UNIVERSITY OF WISCONSIN CIMSS
INDICATES NORTHWESTERLY SHEAR OF ABOUT 20 KNOTS OVER THE SYSTEM. 
WATER VAPOR IMAGERY HINTS THAT THE SHEAR MAY WEAKEN SLIGHTLY AHEAD
OF ARLENE.  GIVEN THE MARGINAL ENVIRONMENT...I HAVE BACKED OFF A BIT
FROM THE PREVIOUS INTENSITY FORECASTS.

THE CENTER IS LOCATED SOMEWHAT TO THE WEST OF THE PREVIOUS...
INFRARED...FIXES AND INITIAL MOTION ESTIMATE IS NOW 305/2.  ARLENE
IS IN A WEAK STEERING ENVIRONMENT...AND THE LATEST NCEP GLOBAL MODEL
FORECAST SHOWS A CONTINUATION OF THIS REGIME FOR THE NEXT COUPLE OF
DAYS. TRACK MODEL GUIDANCE IS AGAIN DIVERGING...WITH THE GFDL AND
BAM GUIDANCE INDICATING A WEST TO WEST-NORTHWEST MOTION...NOGAPS AND
THE AVN A NORTHWEST MOTION...AND THE UKMET SHOWING A MORE NORTHWARD
TRACK.  THE CURRENT NHC FORECAST TRACK IS SOMEWHAT TO THE LEFT OF
THE PREVIOUS ONE AND SIMILAR TO THE NOGAPS/AVN SOLUTIONS.  

PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     13/1500Z 29.2N  58.4W    50 KTS
12HR VT     14/0000Z 29.3N  58.6W    50 KTS
24HR VT     14/1200Z 29.6N  59.0W    55 KTS
36HR VT     15/0000Z 29.9N  59.4W    60 KTS
48HR VT     15/1200Z 30.2N  60.0W    60 KTS
72HR VT     16/1200Z 30.8N  61.0W    60 KTS
 
NNNN