Tropical Depression ALETTA

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TROPICAL DEPRESSION ALETTA DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP012012
800 AM PDT THU MAY 17 2012
 
DURING THE DIURNAL CONVECTIVE MAXIMUM...A NEW BURST OF SHOWERS AND
THUNDERSTORMS HAS DEVELOPED JUST NORTH AND NORTHWEST OF THE CENTER
OF ALETTA.  THE BURST IS LIKELY TO BE TRANSIENT...AS ALETTA IS
EXPERIENCING 20 KT OF SOUTH-SOUTHWESTERLY VERTICAL WIND SHEAR...AND
WATER VAPOR IMAGERY SHOWS DRY AIR TO THE WEST BEING ENTRAINED INTO
THE CYCLONE.  BASED ON THIS COMBINATION...ALETTA IS EXPECTED TO
DECAY INTO A REMNANT LOW IN 36 H OR LESS.  ONE CHANGE FROM THE
PREVIOUS ADVISORY IS TO ADD A 96 H POINT...AS THE LATEST DYNAMICAL
MODEL RUNS SHOW THE REMNANT LOW REMAINING IDENTIFIABLE THROUGH THAT
TIME.
 
THE INITIAL MOTION IS 325/4.  ALETTA IS EMBEDDED IN AN AREA OF WEAK
STEERING CURRENT SOUTH OF A MID-LEVEL TROUGH OVER NORTHWESTERN
MEXICO. THE TRACK GUIDANCE SUGGESTS THAT THE CYCLONE OR ITS
REMNANTS SHOULD MOVE NORTHWARD AND NORTHEASTWARD DURING THE NEXT
48 H...FOLLOWED BY A TURN TOWARD THE EAST AND SOUTHEAST AS A LARGER
DISTURBANCE TO THE EAST BECOMES THE MAIN STEERING MECHANISM.  THE
NEW FORECAST TRACK IS SIMILAR TO THE PREVIOUS TRACK.
 
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/1500Z 12.1N 114.8W   30 KT  35 MPH
 12H  18/0000Z 12.4N 115.1W   25 KT  30 MPH
 24H  18/1200Z 12.8N 115.1W   25 KT  30 MPH
 36H  19/0000Z 13.3N 114.8W   20 KT  25 MPH...POST-TROP/REMNT LOW
 48H  19/1200Z 13.5N 114.2W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  20/1200Z 13.0N 113.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  21/1200Z 12.0N 112.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  22/1200Z...DISSIPATED
 
$$
FORECASTER BEVEN
 
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