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TROPICAL STORM CHANTAL DISCUSSION NUMBER  19
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT MON AUG 20 2001

EARLIER RECON DATA INDICATED CHANTAL REMAINS POORLY ORGANIZED...WITH 
MULTIPLE LOW-LEVEL CIRCULATIONS EMBEDDED WITHIN A BROAD AREA OF LOW 
PRESSURE.  HOWEVER...DURING THE OUTBOUND LEG...THE RECON AIRCRAFT 
PASSED THROUGH A BETTER-DEFINED CIRCULATION NEAR 17.0N 83.9W AT 
0523Z.  THIS CIRCULATION ALSO HAD A 30 KT WIND MAX ASSOCIATED WITH 
IT...AND SATELLITE IMAGERY INDICATES A LARGE THUNDERSTORM CLUSTER 
HAS DEVELOPED OVER OR NEAR THAT CIRCULATION. BASED ON A COMBINATION 
OF THE RECON WIND DATA AND THE CONVECTIVE TRENDS NOTED SATELLITE 
IMAGERY...THE 06Z SYNOPTIC AND ADVISORY POSITIONS WERE KEPT A LITTLE 
FARTHER NORTH THAN THE LAST RECON VORTEX LOCATION.  THIS IS ALSO 
MAINTAINS CONTINUITY WITH EXTRAPOLATED POSITIONS FROM THE PREVIOUS 
ADVISORY MOTION.  RECON ALSO FOUND A 61 KT 850 MB FLIGHT-LEVEL WIND 
ON THE OUTBOUND LEG AT 0552Z...WHICH EQUATES TO ABOUT A 50 KT 
SURFACE WIND.  HOWEVER...THIS WIND REPORT WAS JUST NORTH OF THE 
STRONGEST CONVECTION...SO THE INITIAL INTENSITY IS HELD AT 55 KT.
 
THE INITIAL MOTION ESTIMATE IS 290/13 BASED ON A BLEND OF RECON AND 
SATELLITE POSITION ESTIMATES.  CHANTAL IS EXPECTED TO MAINTAIN A 
GENERAL WEST-NORTHWEST MOTION UNTIL LANDFALL IN ABOUT 18 TO 24 HOURS 
ALONG THE YUCATAN PENINSULA.  THE VAST MAJORITY OF THE MODEL 
GUIDANCE REMAINS TIGHTLY CLUSTERED IN TAKING CHANTAL SLOWLY ACROSS 
THE YUCATAN AND INTO THE SOUTHWEST GULF OF MEXICO IN 36 TO 48 HOURS 
AND THEN TURNING THE CYCLONE MORE WESTWARD AFTERWARDS.  THE OFFICAL 
FORECAST TRACK IS VERY CLOSE TO THE PREVIOUS TRACK AND NEAR THE 
UKMET AND AVN TRACK FORECASTS.

THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS INTENSITY FORECAST. 
CHANTAL IS EXPECTED TO REMAIN IN A SHEARED STATE FOR THE NEXT 36 
HOURS OR SO...AND LITTLE OR NO SIGNIFICANT STRENGTHENING IS 
FORECAST. HOWEVER...IT IS POSSIBLE FOR CHANTAL TO REACH MINIMAL 
HURRICANE INTENSITY JUST BEFORE MAKING LANDFALL OVER YUCATAN AS  
INCREASING FRICTIONAL CONVERGENCE ON THE WEST SIDE MAY HELP TO 
TIGHTEN UP THE LOW-LEVEL CIRCULATION.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     20/0900Z 17.3N  84.8W    55 KTS
12HR VT     20/1800Z 18.1N  86.6W    60 KTS
24HR VT     21/0600Z 19.5N  88.5W    50 KTS...INLAND
36HR VT     21/1800Z 20.6N  90.3W    45 KTS...INLAND
48HR VT     22/0600Z 21.3N  92.0W    55 KTS
72HR VT     23/0600Z 22.0N  94.5W    70 KTS
 
 
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