Tropical Storm ANDRES

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TROPICAL STORM ANDRES DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT FRI MAY 23 2003
 
AFTER LOOKING QUITE DISORGANIZED YESTERDAY AFTERNOON...ANDRES HAS
MADE A CONSIDERABLE COMEBACK THIS MORNING.  THE LOW-LEVEL CENTER
HAS DISAPPEARED UNDER A PERSISTENT CONVECTIVE BURST WITH TOPS
COLDER THAN -80C...AND TWO RECENT SSM/I OVERPASSES SUGGEST THAT THE
CONVECTION IS TRYING TO WRAP AROUND THE NORTH SIDE OF THE CENTER. 
SATELLITE INTENSITY ESTIMATES ARE 30 KT...35 KT...AND 45 KT FROM
TAFB...AFWA...AND SAB RESPECTIVELY.  THE INITIAL INTENSITY IS SET
AT 40 KT BASED ON THE IMPROVED APPEARANCE DURING THE PAST 6 HR.

THE INITIAL MOTION IS 280/18.  ANDRES IS EMBEDDED IN LOW/MID LEVEL
EASTERLY FLOW SOUTH OF A STRONG SUBTROPICAL RIDGE...WHILE A LARGE
MID/UPPER-LEVEL TROUGH COVERS THE AREA WEST OF 135W.  THE RIDGE
SHOULD KEEP THE CYCLONE ON A GENERAL WEST TO WEST-NORTHWEST TRACK
THROUGH 24-36 HR.  BEYOND THAT TIME...THE TROUGH COULD TURN ANDRES
MORE NORTHWARD IF IT IS WELL-ENOUGH DEVELOPED...AS IS SUGGESTED BY
THE BAMD AND BAMM.  HOWEVER...THE CURRENT EXPECTATION IS THAT
ANDRES WILL BE WEAK AND BE STEERED BY THE LOW-LEVEL FLOW.  THE
OFFICIAL FORECAST THEREFORE CALLS FOR A WESTWARD MOTION AFTER 36 HR
WITH A DECREASE IN FORWARD SPEED.  THIS IS IN BEST AGREEMENT WITH
THE NOGAPS.

TO DEAL WITH THE EASY PART OF THE INTENSITY FORECAST...ANDRES SHOULD
CROSS THE 26C ISOTHERM IN 24-30 HR.  AFTER THAT TIME...COOLER WATER
AND SHEAR FROM THE TROUGH SHOULD CAUSE THE SYSTEM TO STEADILY
WEAKEN.  THE TRICKY PART IS WHAT MAY HAPPEN BEFORE ANDRES REACHES
THE COOLER WATER.  THE INTENSITY FORECAST CALLS FOR LITTLE CHANGE
IN STRENGTH...BASED PARTLY ON THE SHIPS MODEL...PARTLY ON THE
EXPECTATION OF CONTINUED SHEAR...AND PARTLY ON THE WAY ANDRES FELL
APART YESTERDAY AFTER LOOKING SIMILAR TO HOW IT DOES NOW. 
HOWEVER...THE STORM IS MOVING OUT OF WESTERLY AND NORTHWESTERLY
UPPER-LEVEL FLOW INTO AN AREA OF SOUTHERLY TO SOUTHWESTERLY FLOW. 
WHILE HARDLY IDEAL...THIS BRINGS UP AN ALTERNATE SCENARIO THAT THE
SHEAR MAY DECREASE OVER ANDRES FOR 12-24 HR AND ALLOW SOME
STRENGTHENING BEFORE THE CYCLONE REACHES COOLER WATER.

FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/0900Z 12.4N 123.3W    40 KT
 12HR VT     23/1800Z 12.8N 125.7W    40 KT
 24HR VT     24/0600Z 13.4N 128.7W    40 KT
 36HR VT     24/1800Z 13.8N 131.1W    35 KT
 48HR VT     25/0600Z 14.1N 133.3W    30 KT
 72HR VT     26/0600Z 14.5N 137.5W    25 KT...DISSIPATING
 96HR VT     27/0600Z 14.5N 141.5W    20 KT...REMNANT LOW
120HR VT     28/0600Z 14.5N 145.5W    20 KT...REMNANT LOW
 
 
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