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TROPICAL STORM ERNESTO DISCUSSION NUMBER   6
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT SUN SEP 03 2000

ERNESTO REMAINS IN A MODERATE TO STRONG SHEAR PATTERN...BUT DEEP
CONVECTION HAS RE-DEVELOPED NEAR THE LOW-LEVEL CIRCULATION CENTER
DURING THE PAST 5 HOURS.  SATELLITE INTENSITY ESTIMATES USING A
SHEAR PATTERN INDICATE THAT ERNESTO IS PROBABLY STILL AT LEAST A
MINIMAL TROPICAL STORM.  OUTFLOW IS FAIR TO THE NORTHEAST AND
RESTRICTED ELSEWHERE.
 
INITIAL MOTION ESTIMATE IS 290/15.  THE SOUTHERLY SHEAR PATTERN WILL
CONTINUE TO IMPART A POLEWARD COMPONENT TO THE TRACK...WHILE THE
MAIN STEERING INFLUENCE WILL BE THE LOW- TO MID-LEVEL EASTERLY FLOW
THROUGH 48 HOURS.  BY 72 HOURS...THE SHEAR IS EXPECTED TO LET UP AND
MOST OF THE STEERING FLOW WILL BE FROM THE SOUTHEAST OR SOUTH.  THE
UKMET MODEL IS THE FASTEST AND MOST AGGRESSIVE OF THE MODELS IN
TAKING ERNESTO RAPIDLY POLEWARD AFTER 48 HOURS...AND EVEN HINTS AT
RECURVATURE.  HOWEVER...THE UKMET HAS A BIAS TOWARD EARLY
RECURVATURE SO THE OFFICIAL TRACK IS A LITTLE TO THE LEFT OF THE
PREVIOUS FORECAST AND BETWEEN THE AVN AND GFDL MODEL FORECASTS.
 
THE INTENSITY FORECAST MAINTAINS ERNESTO AT MINIMAL TROPICAL STORM
STRENGTH OWING TO THE SHEAR PATTERN.  THE MODELS HAVE BEEN
FORECASTING THE SHEAR TO DECREASE FOR THE PAST 3 DAYS...WHICH HAS
YET TO OCCUR.  WV IMAGERY INDICATES ERNESTO WILL BE MOVING INTO A
SHARP NARROW TROUGH IN 12 TO 24 HOURS WHICH MAY WEAKEN THE SYSTEM
DOWN TO THE DEPRESSION LEVEL.  BUT AS LONG AS SOME DEEP CONVECTION
REMAINS NEAR OR OVER PART OF THE LOW-LEVEL CENTER...THEN MINIMAL
TROPICAL STORM INTENSITY CAN BE MAINTAINED.  OF INTEREST ARE THE
GFDL AND SHIPS INTENSITY FORECASTS WHICH STEADILY INTENSIFY ERNESTO
TO 77 KT AND 962 MB IN 72 HOURS...INSPITE OF THE SHEAR PATTERN.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     03/0900Z 18.9N  55.5W    35 KTS
12HR VT     03/1800Z 19.7N  57.5W    35 KTS
24HR VT     04/0600Z 21.0N  60.0W    35 KTS
36HR VT     04/1800Z 22.5N  62.5W    35 KTS
48HR VT     05/0600Z 24.0N  64.0W    35 KTS
72HR VT     06/0600Z 27.0N  66.0W    35 KTS
 
 
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