[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 032035
TCDAT5

TROPICAL STORM ERNESTO DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052012
500 PM AST FRI AUG 03 2012

THE OVERALL STRUCTURE OF ERNESTO HAS BECOME A LITTLE BETTER
ORGANIZED DURING THE PAST SEVERAL HOURS...WITH AN INCREASE IN
BANDING FEATURES AND CENTRAL CONVECTION.  HOWEVER...WESTERLY SHEAR
IS STILL APPARENT WITH MOST OF THE SHOWER AND THUNDERSTORM ACTIVITY
EAST OF THE CENTER.  THE INITIAL INTENSITY IS HELD AT 45 KT PENDING
THE ARRIVAL OF AN AIR FORCE RESERVE PLANE THIS EVENING.  WESTERLY
SHEAR IS FORECAST TO CONTINUE FOR THE NEXT COUPLE OF DAYS...WHICH
COULD IMPEDE STRENGTHENING.  THERE REMAINS A LARGE DIVERGENCE IN
THE INTENSITY GUIDANCE...WITH THE GFS AND ECMWF BASICALLY
DISSIPATING THE SYSTEM AND THE STATISTICAL MODELS SHOWING ERNESTO
BECOMING A HURRICANE IN A COUPLE DAYS.  THE NHC INTENSITY FORECAST
REMAINS NEAR THE INTENSITY CONSENSUS...AND IS CLOSE TO THE PREVIOUS
PREDICTION.  NEEDLESS TO SAY...THIS IS AN UNCERTAIN FORECAST.

ERNESTO CONTINUES TO MOVE TOWARD THE WEST OR 275/18.   THERE IS NO
CHANGE TO THE SYNOPTIC REASONING FROM THE PREVIOUS FORECAST AS THE
CYCLONE REMAINS EMBEDDED WITHIN A FAST EASTERLY FLOW SOUTH OF THE
SUBTROPICAL RIDGE. THIS STEERING PATTERN SHOULD KEEP THE CYCLONE ON
A GENERAL WESTWARD TRACK FOR THE NEXT COUPLE OF DAYS.  AFTER
THAT...THE RIDGE WILL PROBABLY WEAKEN SOMEWHAT...CAUSING ERNESTO TO
SLOW DOWN AND GAIN A LITTLE LATITUDE.  HOWEVER...TRACK MODELS HAVE
A LARGE SPREAD IN THE LONG TERM WITH LARGE DIFFERENCES IN THE
STRENGTH OF THE RIDGE.  THE OFFICIAL FORECAST IS NUDGED TO THE
WEST...AND LIES ON THE SOUTH SIDE OF THE MODEL CONSENSUS.  ALTHOUGH
THE NHC FORECAST IS WELL TO THE NORTH OF THE NORMALLY RELIABLE GFS
AND ECMWF MODELS...THESE MODELS ARE SHOWING A RATHER WEAK SYSTEM IN
A FEW DAYS...AND ARE NOT THOUGHT TO BE THE MOST REPRESENTATIVE IN
THIS CASE.



FORECAST POSITIONS AND MAX WINDS

INIT  03/2100Z 13.9N  64.1W   45 KT  50 MPH
 12H  04/0600Z 14.2N  66.7W   45 KT  50 MPH
 24H  04/1800Z 14.7N  69.9W   50 KT  60 MPH
 36H  05/0600Z 15.3N  73.2W   50 KT  60 MPH
 48H  05/1800Z 15.9N  76.5W   55 KT  65 MPH
 72H  06/1800Z 17.0N  81.0W   65 KT  75 MPH
 96H  07/1800Z 19.0N  84.5W   75 KT  85 MPH
120H  08/1800Z 21.0N  88.0W   65 KT  75 MPH...INLAND

$$
FORECASTER BLAKE



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