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TROPICAL STORM ALEX DISCUSSION NUMBER  15
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT THU JUL 30 1998
 
ALEX IS GENERATING A CENTRAL AREA OF INTENSE CONVECTION WITH A
FAIRLY SYMMETRICAL HIGH-LEVEL OUTFLOW.  AT AN INTERMEDIATE
LEVEL...HOWEVER...THERE REMAINS A DISTINCT SSW CURRENT ACROSS THE
STORM ASSOCIATED WITH THE UPPER TROUGH AHEAD OF THE STORM.  THIS IS
JUST ONE PART OF A COMPLICATED CIRCULATION ALOFT THAT INCLUDES A
WELL-DEFINED VORTEX SEEN IN WATER VAPOR IMAGERY ABOUT 10 DEGREES TO
THE NORTHWEST OF ALEX.  THE AVN MODEL SHOWS THAT VORTEX AT 300-500
MB.  

THE INTENSE OUTFLOW AT CIRRUS LEVEL HAS OBSCURED THE CENTRAL
FEATURES...MAKING POSITIONING SOMEWHAT MORE DIFFICULT.  ANALYSES
FROM TAFB...SAB..AND AFWA...HOWEVER...INDICATE THAT A HEADING TOWARD
THE WNW HAS BEGUN...PERHAPS BECAUSE THE SYSTEM IS NOW DEEP ENOUGH TO
RESPOND MORE TO THE UPPER LEVEL FLOW IN ITS ENVIRONMENT.  THE MOTION
IS ESTIMATED AT 290/11 KT.  WIND SPEED IS NEAR 45 KT.
 
THE PATTERN ALOFT IS FORECAST TO REMAIN COMPLEX...WITH THE AVN
KEEPING A VORTEX TO THE NW-N OF ALEX THROUGH 72 HOURS.  THIS
IS INTERPRETED AS A GENERAL WEAKNESS IN THE HEIGHT PATTERN THAT
SHOULD ALLOW FOR AN INCREASE IN THE NORTHWARD COMPONENT.  THE
RELATIVE POSITIONS OF THE FEATURES WILL PROBABLY INFLUENCE HOW
SMOOTH THE TRANSITION IN TRACK WILL BE.  THE TRACK GUIDANCE SHOWS
LITTLE DIVERSITY.  THE OFFICIAL FORECAST IS NEAR THE CENTER OF THE
CLUSTER OF MODEL TRACKS AND VERY SIMILAR TO THE 18 AVN AND 12Z
NOGAPS FORECASTS.

THE INTENSITY FORECAST IS THE SAME AS 6 HOURS AGO.
 
RAPPAPORT
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     31/0300Z 15.8N  47.6W    45 KTS
12HR VT     31/1200Z 16.3N  49.3W    50 KTS
24HR VT     01/0000Z 17.3N  51.7W    55 KTS
36HR VT     01/1200Z 18.4N  53.9W    60 KTS
48HR VT     02/0000Z 19.7N  56.3W    65 KTS
72HR VT     03/0000Z 23.5N  60.5W    65 KTS
 
 
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