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Tropical Storm ERNESTO (Text)

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TROPICAL STORM ERNESTO DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052012
1100 PM AST FRI AUG 03 2012

CONVECTION HAS BECOME MORE CONCENTRATED NEAR THE CENTER OF ERNESTO
DURING THE PAST SEVERAL HOURS.  HOWEVER...SATELLITE INTENSITY
ESTIMATES AND AN ABBREVIATED HURRICANE HUNTER MISSION SUGGEST THAT
THIS HAS NOT YET RESULTED IN INTENSIFICATION.  THE INITIAL
INTENSITY REMAINS 45 KT...AND THE CENTRAL PRESSURE OF 1003 MB IS
BASED ON EXTRAPOLATION OF THE HURRICANE HUNTER DATA.  ANALYSIS FROM
CIMSS AT THE UNIVERSITY OF WISCONSIN SUGGEST THAT VERTICAL WIND
SHEAR IS DECREASING OVER ERNESTO...AND THE OUTFLOW HAS IMPROVED IN
THE WESTERN SEMICIRCLE.

THE INITIAL MOTION IS 275/16...A LITTLE SLOWER THAN BEFORE.  A
STRONG LOW/MID-LEVEL SUBTROPICAL RIDGE TO THE NORTH OF ERNESTO
SHOULD KEEP THE CYCLONE ON A GENERAL WESTWARD TRACK FOR THE NEXT
36-48 HR...AND THE NEW FORECAST TRACK IS SIMILAR TO THE OLD TRACK
DURING THIS PERIOD.  AFTER THAT TIME...THE TRACK FORECAST BECOMES
LOWER CONFIDENCE.  THE GLOBAL MODELS FORECAST A DEVELOPING MID/
UPPER-LEVEL TROUGH OVER THE EASTERN UNITED STATES FROM 72-120 HR...
WHICH IS EXPECTED TO CAUSE A WEAKNESS IN THE RIDGE OVER THE THE
NORTHERN GULF OF MEXICO AND THE ADJACENT LAND AREAS.  THE GFDL...
UKMET...AND NOGAPS MODELS RESPOND TO THIS BY FORECASTING ERNESTO TO
MOVE NORTHWESTWARD NEAR THE YUCATAN CHANNEL INTO THE SOUTHERN GULF
OF MEXICO.  ON THE OTHER HAND...THE ECMWF AND GFS FORECAST ERNESTO
TO BE TOO FAR SOUTH TO RESPOND TO THE WEAKNESS...AND THUS SHOW THE
CYCLONE MOVING INLAND OVER THE SOUTHERN YUCATAN PENINSULA OR
CENTRAL AMERICA.  BASED ON THE PREMISE THAT ERNESTO WILL BE FAR
ENOUGH NORTH AND STRONG ENOUGH TO RESPOND TO THE WEAKNESS...THE
LATTER PART OF THE NEW FORECAST TRACK IS NUDGED A LITTLE TO THE
NORTH OF THE PREVIOUS FORECAST.

THE INTENSITY GUIDANCE REMAINS VERY DIVERGENT.  THE STATISTICAL-
DYNAMICAL MODELS FORECAST SIGNIFICANT INTENSIFICATION...WITH THE
LGEM CALLING FOR ERNESTO TO BECOME A MAJOR HURRICANE IN 96 HR.  THE
DYNAMICAL MODELS OFFER A DISSENTING VIEW...WITH THE GFDL AND
HWRF PREDICTING LITTLE CHANGE IN STRENGTH UNTIL ABOUT 96 HR.  IN
ADDITION...THE ECMWF FORECASTS ERNESTO TO REMAIN VERY WEAK.  IT IS
UNCLEAR WHAT ARE THE NEGATIVE FACTORS THAT THE DYNAMICAL MODELS ARE
SEEING...SINCE THE SHEAR IS FORECAST TO BE LIGHT AFTER 24 HR AND
THE SEA SURFACE TEMPERATURES ARE VERY WARM.  THE NEW INTENSITY
FORECAST SHOWS A LITTLE MORE INTENSIFICATION THAN THE PREVIOUS
FORECAST THROUGH 48 HR.  AFTER THAT...IT IS THE SAME AS THE
PREVIOUS FORECAST DUE TO THE DIVERGENT GUIDANCE.

INTERESTS IN JAMAICA SHOULD MONITOR THE PROGRESS OF ERNESTO...AS A
TROPICAL STORM WATCH COULD BE REQUIRED FOR PORTIONS OF THE ISLAND ON
SATURDAY. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  04/0300Z 13.9N  65.6W   45 KT  50 MPH
 12H  04/1200Z 14.2N  67.9W   50 KT  60 MPH
 24H  05/0000Z 14.7N  71.3W   55 KT  65 MPH
 36H  05/1200Z 15.4N  74.8W   55 KT  65 MPH
 48H  06/0000Z 16.1N  77.9W   60 KT  70 MPH
 72H  07/0000Z 17.5N  82.0W   65 KT  75 MPH
 96H  08/0000Z 19.5N  85.5W   75 KT  85 MPH
120H  09/0000Z 22.0N  88.9W   65 KT  75 MPH
 
$$
FORECASTER BEVEN
 
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