000
WTPZ42 KNHC 240232
TCDEP2
TROPICAL STORM ANDRES DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP022009
800 PM PDT TUE JUN 23 2009
 
SATELLITE IMAGERY INDICATES A RECENT BURST OF CONVECTION TO THE EAST
OF THE CENTER...THOUGH THE CONVECTION REMAINS RATHER ASYMMETRIC DUE
TO MODERATE NORTHEASTERLY SHEAR.  IN SPITE OF THE CONVECTIVE
BURST...ANDRES HAS A RAGGED SATELLITE APPEARANCE WITH POORLY-
DEFINED BANDING FEATURES.  FINAL DVORAK T-NUMBERS HAVE DECREASED
OVER THE PAST 6-12 HR...AND ON THIS BASIS ANDRES IS DOWNGRADED TO A
60 KT TROPICAL STORM.  THE EARLIER DISPARITY BETWEEN SATELLITE AND
RECONNAISSANCE DATA SUGGESTS THAT GREATER-THAN-NORMAL UNCERTAINTY
IS ASSOCIATED WITH THIS INTENSITY ESTIMATE.  THE OFFICIAL INTENSITY
FORECAST CALLS FOR A GRADUAL WEAKENING OVER THE NEXT 24
HOURS...MOSTLY A RESULT OF A PERSISTENT NORTHEASTERLY SHEAR OF 20
TO 25 KT AND A GRADUAL DECLINE IN OCEANIC HEAT CONTENT. 
THEREAFTER...A STEADIER AND MORE RAPID WEAKENING IS PROJECTED ONCE
ANDRES REACHES EVEN COOLER WATERS...AND THE CYCLONE IS FORECAST TO
BE A REMNANT LOW BY 72 HOURS.  THE INTENSITY FORECAST IS CLOSELY IN
LINE WITH BOTH SHIPS AND ICON.
 
ANDRES HAS RECENTLY TRACKED A LITTLE MORE TO THE LEFT...WITH AN
INITIAL MOTION OF 305/9. SEVERAL OF THE DYNAMICAL MODELS CONTINUE
TO INDICATE SIGNIFICANT INTERACTION BETWEEN THE CYCLONE AND THE
NEARBY MEXICAN LANDMASS...RESULTING IN AN ABRUPT DISSIPATION.
HOWEVER...THE GUIDANCE INDICATES MID-LEVEL RIDGING REASSERTING
ITSELF NORTH OF THE CYCLONE AS SOON AS 12 HOURS FROM NOW...WHICH
SHOULD CAUSE THE TRACK TO GRADUALLY BEND MORE WEST-NORTHWEST AS THE
CENTER MOVES AWAY FROM THE MEXICAN COAST.  THE MORE LEFTWARD
INITIAL TRACK AND THE STRENGTHENING RIDGE ARE LIKELY INDICATIONS
THAT ANDRES SHOULD AVOID LANDFALL IN SOUTHWEST MEXICO BUT SHOULD BE
CLOSE ENOUGH TO CAUSE POSSIBLE TROPICAL STORM CONDITIONS. BY 48
HOURS...A WEAKER ANDRES SHOULD SLOW DOWN AND BE STEERED MORE TOWARD
THE WEST AS A RESULT OF WEAK LOW-LEVEL RIDGING FORECAST SOUTHWEST
OF BAJA CALIFORNIA.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/0300Z 19.1N 106.0W    60 KT
 12HR VT     24/1200Z 20.0N 107.0W    55 KT
 24HR VT     25/0000Z 21.0N 108.2W    50 KT
 36HR VT     25/1200Z 21.7N 109.8W    40 KT
 48HR VT     26/0000Z 22.2N 111.2W    30 KT
 72HR VT     27/0000Z 23.0N 113.5W    25 KT...REMNANT LOW
 96HR VT     28/0000Z...DISSIPATED
 
$$
FORECASTER KIMBERLAIN/BEVEN