Tropical Storm IRWIN

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TROPICAL DEPRESSION IRWIN DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 PM PDT SAT AUG 27 2005
 
ENHANCED INFRARED IMAGERY DEPICTS A VERY SMALL AREA OF CONVECTION
SHEARED ABOUT 145 NM TO THE NORTHWEST OF THE POORLY DEFINED
CIRCULATION.  DVORAK T-NUMBERS HAVE DROPPED TO 25 AND 30
KT...THEREFORE...THE INITIAL INTENSITY IS LOWERED TO TROPICAL
DEPRESSION STRENGTH.  THE MAJORITY OF THE DYNAMICAL
MODELS...INCLUDING THE GFDL AND THE FSU
SUPERENSEMBLE...DISSIPATE THE SYSTEM IN 48 HOURS OR LESS.  SHIPS
INDICATES THAT THE EAST TO SOUTHEASTERLY SHEAR WILL PERSIST THROUGH
THE PERIOD.  IRWIN IS ALSO EXPECTED TO MOVE THROUGH A DRYER MORE
STABLE ENVIRONMENT.  THE INTENSITY FORECAST CALLS FOR DISSIPATION
IN 24 HOURS...FURTHER DEGENERATING INTO A REMNANT LOW IN 36 HOURS.   
 
THE INITIAL MOTION IS ESTIMATED AT 270/8.  AN EAST TO WEST ORIENTED
LOW TO MID-LEVEL RIDGE TO THE NORTH OF THE TROPICAL CYCLONE IS
EXPECTED TO INFLUENCE A GENERALLY WESTWARD MOTION THROUGH THE
FORECAST PERIOD.  THE GFS AND THE ECMWF SUGGEST A LOW TO MID LEVEL
HIGH BUILDING JUST TO THE WEST OF IRWIN DURING THE NEXT 24
HOURS...CAUSING THE DEPRESSION TO MOVE MORE WEST-SOUTHWESTWARD. 
THE OTHER AVAILABLE MODELS INDICATE A WESTWARD MOTION OVER THE NEXT
3 DAYS.  THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS PACKAGE
AND FOLLOWS THE CONU CONSENSUS.     
 
FORECASTER ROBERTS/AVILA
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      28/0300Z 17.2N 114.3W    30 KT
 12HR VT     28/1200Z 17.1N 115.6W    25 KT
 24HR VT     29/0000Z 17.1N 117.0W    25 KT...DISSIPATING
 36HR VT     29/1200Z 17.1N 118.4W    25 KT...REMNANT LOW
 48HR VT     30/0000Z 17.1N 119.8W    20 KT...REMNANT LOW
 72HR VT     31/0000Z 17.0N 122.6W    20 KT...REMNANT LOW
 96HR VT     01/0000Z...DISSIPATED
 
 
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