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TROPICAL STORM ERIN DISCUSSION NUMBER   8
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT MON SEP 03 2001
 
THE INITIAL MOTION ESTIMATE IS 290/16 BASED ON LOCATING A LOW LEVEL 
CLOUD CENTER ON VISIBLE IMAGERY.  THE TRACK FORECAST PHILOSOPHY IS 
UNCHANGED.  THE 06Z AVIATION MODEL FORECASTS AN EAST/WEST RIDGE TO 
PERSIST TO THE NORTH OF THE STORM.  ALL OF THE TRACK GUIDANCE MODELS 
RESPOND WITH A GENERAL WEST-NORTHWEST MOTION FOR 72 HOUR WITH 
DIRECTION OF MOTION VARYING BETWEEN 290 AND 320 DEGREES.  THE 
OFFICIAL FORECAST TRACK IS AN UPDATE OF THE PREVIOUS ADVISORY...ON 
THE LEFT SIDE OF THE ENVELOPE OF GUIDANCE.  ONLY THE GFDL IS LEFT OF 
THE OFFICIAL TRACK.

ERIN LOOKS RAGGED THIS MORNING WITH AN EXPOSED LOW LEVEL CENTER 
DISPLACE SOUTHWEST OF THE MAIN CDO FEATURE.  THE CDO CLOUD TOPS ARE 
ALSO WARMING.  THE INITIAL WIND SPEED OF 50 KNOTS...BASED ON DVORAK 
INTENSITY ESTIMATES MAY BE ON THE HIGH SIDE.  A DRIFTING BUOY 
LOCATED ABOUT 60 N MI WEST OF THE CENTER REPORTED A NORTH WIND AT 20 
KNOTS AND 1008.4 MB AT 11Z.  THE BUOY HAD 31 KNOTS AT 10Z.  THE 
TROPICAL STORM FORCE WINDS ARE PROBABLY CONFINED TO THE NORTHEAST OF 
THE CENTER.  THE SHIPS MODEL DIAGNOSIS OF VERTICAL SHEAR IS 22 KNOTS 
DECREASING TO 14 KNOTS AT 36 HOURS SO THERE IS STILL A POTENTIAL FOR 
STRENGTHENING.  THE OFFICIAL FORECAST INCREASES THE WIND TO 70 KNOTS 
IN 72 HOURS COMPARED TO 66 KNOTS FROM THE SHIPS MODEL.

FORECASTER LAWRENCE
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     03/1500Z 16.3N  46.3W    50 KTS
12HR VT     04/0000Z 17.0N  48.3W    50 KTS
24HR VT     04/1200Z 17.9N  51.1W    55 KTS
36HR VT     05/0000Z 18.9N  53.5W    60 KTS
48HR VT     05/1200Z 19.9N  55.8W    65 KTS
72HR VT     06/1200Z 22.0N  59.5W    70 KTS
 
 
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