Tropical Storm ANDRES

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TROPICAL STORM ANDRES DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT THU MAY 22 2003
 
WHILE ANDRES REMAINS SHEARED FROM THE WEST-NORTHWEST...IT LOOKS MUCH
HEALTHIER THAN 24 HR AGO.  THE LOW-LEVEL CENTER IS NEAR OR POSSIBLY
UNDER THE MAIN CONVECTION...AND THE CYCLONE IS MAINTAINING CLOUD
TOPS COLDER THAN -80C IN THE CONVECTIVE AREA.  SATELLITE INTENSITY
ESTIMATES ARE 45 KT FROM SAB AND 35 KT FROM TAFB AND AFWA.  THE
INITIAL INTENSITY IS INCREASED TO 40 KT.  SINCE THE CENTER COULD
ACTUALLY BE UNDER THE DEEP CONVECTIVE OVERCAST...THERE IS A CHANCE
THAT ANDRES IS STRONGER THAN 40 KT.

THE INITIAL MOTION REMAINS 280/16.  WATER VAPOR IMAGERY INDICATES
THE PERSISTENT MID/UPPER-LEVEL ANTICYCLONE NORTH OF ANDRES IS NOW
NEAR 21N115W.  A BROAD TROUGH COVERS THE AREA N OF 15N W OF 130W. 
THE RIDGE SHOULD KEEP ANDRES ON A GENERALLY WEST-NORTHWEST TRACK
FOR THE NEXT THREE DAYS...AND NHC GUIDANCE AGREES WITH THIS
SCENARIO.  THE OFFICIAL FORECAST THUS CALLS FOR A 280-290 DEGREE
MOTION FOR THE NEXT THREE DAYS...DOWN THE MIDDLE OF THE GUIDANCE
ENVELOPE.  LARGE-SCALE MODELS FORECAST THAT TROUGHING SHOULD LINGER
BETWEEN 140W AND THE HAWAIIAN ISLANDS IN THE 3-5 DAY TIME FRAME. 
HOWEVER...THIS IS MOREL LIKELY TO SHEAR ANDRES THAN STEER IT...THUS
THE FORECAST CALLS FOR A CONTINUED WEST-NORTHWESTWARD MOTION DURING
THAT TIME.
 
THE INTENSITY FORECAST REMAINS PROBLEMATIC.  THE 200 MB HIGH THAT IS
AND HAS BEEN FORECAST BY THE GFS...NOGAPS...AND UKMET HAS YET TO
PUT IN AN APPEARANCE.  TO THE CONTRARY...WATER VAPOR IMAGERY SHOWS
STRONG UPPER-LEVEL WESTERLIES COVERING THE AREA WEST OF 122W. 
SHOULD ANDRES HIT THESE...THE STORM WOULD LIKELY WEAKEN.  IF THE
ANTICYCLONE FORMS...ANDRES SHOULD STRENGTHEN SIGNIFICANTLY AND
COULD BECOME A HURRICANE.  INDEED...FOR THE FIRST TIME THE SHIPS
MODEL BRINGS ANDRES TO NEAR HURRICANE STRENGTH IN 48-60 HR. 
HOWEVER...THERE NEEDS TO BE BETTER EVIDENCE OF DECREASING SHEAR
BEFORE THAT BECOMES THE OFFICIAL FORECAST.  SINCE ANDRES IS
STRENGTHENING DESPITE THE SHEAR...THE LOW-CONFIDENCE FORECAST WILL
CALL FOR SLOW DEVELOPMENT THROUGH 48 HR.  ANDRES SHOULD REACH THE
26C ISOTHERM AT ABOUT 72 HR...AND THAT COMBINED WITH SIGNIFICANT
SHEAR FROM THE TROUGH SHOULD WEAKEN THE STORM AFTER THAT TIME. 
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0900Z 10.9N 115.9W    40 KT
 12HR VT     22/1800Z 11.3N 118.1W    45 KT
 24HR VT     23/0600Z 11.9N 120.8W    50 KT
 36HR VT     23/1800Z 12.5N 123.4W    55 KT
 48HR VT     24/0600Z 13.1N 125.6W    55 KT
 72HR VT     25/0600Z 14.5N 130.0W    55 KT
 96HR VT     26/0600Z 15.5N 134.5W    45 KT
120HR VT     27/0600Z 16.5N 139.5W    30 KT
 
 
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