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Tropical Storm ERNESTO (Text)

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TROPICAL STORM ERNESTO DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052012
1100 PM AST THU AUG 02 2012
 
SATELLITE IMAGERY AND RADAR DATA FROM BARBADOS INDICATE ERNESTO HAS
BECOME A LITTLE BETTER ORGANIZED OVER THE PAST 6 HOURS. THESE DATA
ALSO INDICATE THAT THE CENTER OF ERNESTO HAS MOVED OR DEVELOPED
FARTHER NORTH OF THE PREVIOUS POSITION. THE INITIAL INTENSITY IS
SUPPORTED BY THE UW-CIMSS ADT INTENSITY ESTIMATE OF T3.0/45 KT.

THE INITIAL MOTION ESTIMATE IS 275/19 KT BASED PRIMARILY ON RADAR
DATA AND MICROWAVE SATELLITE POSITIONS OVER THE PAST 9 HOURS. A
DEEP-LAYER RIDGE SITUATED TO THE NORTH OF THE GREATER AND LESSER
ANTILLES IS EXPECTED TO REMAIN INTACT THROUGHOUT THE FORECAST
PERIOD AND STEER ERNESTO ON A WEST TO WEST-NORTHWESTWARD TRACK. BY
DAYS 4 AND 5...A WEAKNESS IN THE RIDGE IS FORECAST TO DEVELOP
ACROSS THE GULF OF MEXICO...WHICH SHOULD RESULT IN A SIGNIFICANT
DECREASE IN THE FORWARD SPEED OF THE CYCLONE. THERE IS A LARGE
SPREAD IN THE NHC MODEL GUIDANCE WITH THE ECMWF AND GFS MODELS
TAKING ERNESTO INTO CENTRAL AMERICA...WHILE THE UKMET AND GFDL
MODELS TAKE THE CYCLONE TO WESTERN CUBA BY 120 HOURS. THE REST OF
THE GUIDANCE LIES BETWEEN THESE TWO EXTREMES. THE OFFICIAL FORECAST
HAS BEEN SHIFTED NORTH OF THE PREVIOUS ADVISORY TRACK... MAINLY DUE
TO THE MORE POLEWARD INITIAL POSITION...AND IS CLOSE TO THE NHC
CONSENSUS MODEL...TVCN...WHICH HAS SHOWN VERY LITTLE CROSS-TRACK
VARIATION OVER THE PAST 36 HOURS.

THE RATHER FAST FORWARD SPEED COMBINED WITH SOME MODERATE VERTICAL
WIND SHEAR FOR THE NEXT 12-24 HOURS SHOULD ONLY ALLOW FOR SOME
SLIGHT STRENGTHENING TO OCCUR. AFTER THAT...HOWEVER...THE GFS-BASED
SHIPS MODEL INDICATES THE SHEAR SHOULD WEAKEN TO LESS THAN 10 KT
AND REMAIN THAT WAY FOR THE REMAINDER OF THE FORECAST PERIOD. THE
COMBINATION OF WARMER SSTS...INCREASING MID-LEVEL MOISTURE...AND
DECREASING SHEAR SHOULD ALLOW FOR MORE MODEST INTENSIFICATION TO
OCCUR. IN FACT...IF ERNESTO REMAINS CLOSE TO THE FORECAST TRACK... 
MORE SIGNIFICANT STRENGTHENING COULD OCCUR BY DAYS 4 AND 5 AS
INDICATED BY THE LGEM AND STATISTICAL HFIP EXPERIMENTAL INTENSITY
MODELS... WHICH MAKE ERNESTO A MAJOR HURRICANE BY 120 HOURS WHEN
THE CYCLONE WILL BE IN IDEAL ENVIRONMENTAL AND OCEANIC CONDITIONS.
HOWEVER... THE LARGE SPREAD IN THE TRACK MODELS AND UNCERTAINTY IN
WHETHER ERNESTO WILL BE AFFECTED BY LAND REQUIRES THAT THE
INTENSITY FORECAST REMAIN CONSERVATIVE AT THIS TIME.

FORECAST POSITIONS AND MAX WINDS
 
INIT  03/0300Z 13.4N  58.3W   45 KT  50 MPH
 12H  03/1200Z 13.7N  61.1W   50 KT  60 MPH
 24H  04/0000Z 14.0N  64.4W   50 KT  60 MPH
 36H  04/1200Z 14.4N  67.5W   55 KT  65 MPH
 48H  05/0000Z 15.0N  70.6W   60 KT  70 MPH
 72H  06/0000Z 16.3N  76.6W   65 KT  75 MPH
 96H  07/0000Z 17.9N  81.1W   70 KT  80 MPH
120H  08/0000Z 19.7N  84.6W   75 KT  85 MPH
 
$$
FORECASTER STEWART
 
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