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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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