Tropical Storm EUGENE

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TROPICAL STORM EUGENE DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP052011
800 AM PDT SUN JUL 31 2011
 
THE CYCLONE CONTINUES TO EXHIBIT THE STRUCTURE OF A SHEARED
TROPICAL CYCLONE IN SATELLITE IMAGERY...WITH THE CENTER APPARENTLY
NEAR THE NORTHEASTERN EDGE OF A DEEP CIRCULAR MASS OF CONVECTION.
NEVERTHELESS...THE OVERALL CLOUD PATTERN HAS BECOME BETTER ORGANIZED
DURING THE LAST SIX HOURS...WITH CLOUD TOP TEMPERATURES COOLING AND
THE APPEARANCE OF A NEW BAND OVER THE WESTERN SEMICIRCLE.  DVORAK
SATELLITE ESTIMATES AT 1200 UTC WERE 2.5 AND 2.0 FROM TAFB AND
SAB...RESPECTIVELY...SUGGESTING AN INTENSITY CLOSE TO TROPICAL
STORM STRENGTH.  SINCE THAT TIME...THE ORGANIZATION OF THE CLOUD
PATTERN HAS CONTINUED TO INCREASE. THE DEPRESSION IS THEREFORE
BEING UPGRADED TO TROPICAL STORM EUGENE WITH AN INITIAL INTENSITY
OF 35 KT.

THE CENTER OF THE CYCLONE HAS BEEN DIFFICULT TO LOCATE...AND THUS
THE INITIAL MOTION REMAINS A BIT UNCERTAIN.  THE BEST ESTIMATE BASED
UPON RECENT FIXES IS 285/09.  EUGENE SHOULD BE STEERED ON A GENERAL
WEST-NORTHWESTWARD COURSE DURING THE NEXT SEVERAL DAYS...ON THE
SOUTH SIDE OF A STRONG MID-/UPPER-LEVEL RIDGE CENTERED OVER THE
CENTRAL PLAINS.  THE OFFICIAL NHC TRACK FORECAST IS ADJUSTED
SLIGHTLY TO THE LEFT AND CONTINUES TO LIE ON THE SOUTH SIDE OF
THE GUIDANCE ENVELOPE...CLOSER TO THE UKMET/ECMWF MODELS WHICH HAD
BETTER INITIALIZATIONS OF THE STORM.
 
UW CIMSS AND SHIPS SHEAR ANALYSES CONTINUE TO DIAGNOSE 15-20 KT OF
NORTHEASTERLY SHEAR OVER EUGENE.  GLOBAL MODELS SUGGEST THAT THE
SHEAR SHOULD CONTINUE DURING THE NEXT SEVERAL DAYS...LIKELY
HAMPERING SIGNIFICANT INTENSIFICATION.  LATE IN THE FORECAST
PERIOD...THE SHEAR COULD DECREASE SOME BUT EUGENE WILL BE REACHING
PROGRESSIVELY COOLER WATERS AROUND THAT TIME.  A WEAKENING TREND
SHOULD COMMENCE THEN...POSSIBLY AT A FASTER RATE BY DAY 5.  THE
OFFICIAL NHC INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ONE IN
BEST AGREEMENT WITH THE SHIPS/LGEM GUIDANCE.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  31/1500Z 11.0N 100.5W   35 KT  40 MPH
 12H  01/0000Z 11.5N 101.8W   40 KT  45 MPH
 24H  01/1200Z 12.2N 103.5W   45 KT  50 MPH
 36H  02/0000Z 13.1N 105.4W   50 KT  60 MPH
 48H  02/1200Z 13.8N 107.2W   60 KT  70 MPH
 72H  03/1200Z 15.0N 110.5W   65 KT  75 MPH
 96H  04/1200Z 16.5N 113.5W   65 KT  75 MPH
120H  05/1200Z 18.0N 116.0W   50 KT  60 MPH
 
$$
FORECASTER KIMBERLAIN
 
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