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TROPICAL STORM ERNESTO DISCUSSION NUMBER   2
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT SAT SEP 02 2000
 
TROPICAL DEPRESSION EIGHT HAS BECOME BETTER ORGANIZED OVERNIGHT AND
DEEP CONVECTION HAS INCREASED SIGNIFICANTLY NEAR THE LOW-LEVEL
CENTER...AND THE SYSTEM HAS BEEN UPGRADED TO TROPICAL STORM ERNESTO.
THE INITIAL INTENSITY OF 35 KT IS BASED ON A SATELLITE INTENSITY
ESTIMATE OF 35 KT FROM TAFB AND 30 KT BUOY REPORTS WELL NORTH OF
THE LOW-LEVEL CENTER.  OUTFLOW HAS IMPROVED TO THE NORTH...BUT IS
RESTRICTED ELSEWHERE DUE TO SOUTHERLY SHEAR.

INITIAL MOTION ESTIMATE IS 290/12.  DUE TO THE SOUTHERLY SHEAR ON
ERNESTO...THE LOCATION OF THE LOW-LEVEL CENTER IS SOMEWHAT
UNCERTAIN.  I HAVE KEPT THE CENTER ALONG THE SOUTHERN EDGE OF THE
LARGE CONVECTIVE BURST DUE TO THE SOUTHERLY SHEAR...AND I AM NOT
READY TO CONSIDER THE CONVECTIVE PATTERN AS A CDO AS A RESULT OF
THE SHEAR PATTERN.  IF THE CENTER IS FARTHER NORTH INTO THE DEEP
CONVECTION...THEN BOTH THE TRACK AND INTENSITY FORECASTS WILL BE
OFF.  PUTTING ALL THE AMBIGUITIES ASIDE...ERNESTO IS EXPECTED TO
TRACK WEST-NORTHWEST THROUGH 48 HOURS AND THEN TURN MORE TOWARD THE
WEST AFTERWARDS AS THE TROUGH TO THE WEST WEAKENS AND MOVES WEST...
WHICH ALLOWS THE SUBTROPICAL RIDGE TO BUILD WESTWARD NORTH OF THE
CYCLONE.  THE OFFICIAL FORECAST IS CLOSE TO THE UKMET AND NOGAPS
MODELS...AND A LITTLE NORTH OF THE GFDL MODEL.

THE INTENSITY FORECAST HAS EVEN GREATER UNCERTAINTY DUE TO THE
CURRENT SHEAR PATTERN WHICH IS FORECAST BY ALL THE GLOBAL MODELS TO
WEAKEN SIGNIFICANTLY AND SHIFT WESTWARD THROUGH THE PERIOD.  THE
OFFICIAL FORECAST IS CLOSE TO SHIFOR AND THE GFDL MODEL.  THE SHIPS
INTENSITY MODEL TAKES ERNESTO UP TO 72 KT IN 72 HOURS INSPITE OF 
20 KT OF SHEAR FORECAST.  THIS MAY BE DUE TO THE CURRENT SOUTHERLY
SHEAR VECTOR SHIFTING TO MORE SOUTHEASTERLY IN 72 HOURS WHICH WOULD
ALLOW FOR MORE INTENSIFICATION THAN THE OFFICIAL FORECAST INDICATES.

 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     02/0900Z 16.1N  49.8W    35 KTS
12HR VT     02/1800Z 16.7N  51.6W    40 KTS
24HR VT     03/0600Z 17.6N  53.9W    40 KTS
36HR VT     03/1800Z 18.4N  56.3W    40 KTS
48HR VT     04/0600Z 19.0N  58.5W    40 KTS
72HR VT     05/0600Z 20.0N  63.5W    45 KTS
 
 
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