Tropical Storm FAUSTO

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TROPICAL STORM FAUSTO DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP072008
800 PM PDT WED JUL 16 2008
 
THE CENTER IS VERY DIFFICULT TO LOCATE...BUT IS BELIEVED TO BE NEAR
THE NORTHERN EDGE OF THE MAIN CONVECTIVE BLOB.  A BLEND OF THE MOST
RECENT DVORAK CLASSIFICATIONS GIVES 40 KT FOR THE INITIAL
INTENSITY...ALTHOUGH GIVEN THE UNCERTAIN CENTER LOCATION I AM NOT
ESPECIALLY CONFIDENT IN THIS ASSESSMENT.  NORTHEASTERLY SHEAR IS
HAMPERING DEVELOPMENT...AND THE GLOBAL MODELS SUGGEST THAT THIS
COULD REMAIN A FACTOR FOR THE NEXT FEW DAYS.  THERE IS CONSIDERABLE
SPREAD IN THE INTENSITY GUIDANCE.  THE SHIPS MODEL IS MOST
AGGRESSIVE...BRINGING FAUSTO TO ABOUT 80 KT IN 3 DAYS...WHILE THE
HWRF SHOWS VIRTUALLY NO STRENGTHENING AT ALL.    IN BETWEEN ARE THE
LGEM AND GFDL MODELS...WITH WHICH THE OFFICIAL FORECAST IS IN GOOD
AGREEMENT.  THE SHIPS MODEL DIAGNOSES ONLY 10 KT OF SHEAR FROM THE
GFS ANALYSIS...WHICH SEEMS UNREALISTICALLY LOW GIVEN THE CURRENT
CLOUD PATTERN AND UPPER-LEVEL SATELLITE WINDS.

THE INITIAL MOTION IS A HIGHLY UNCERTAIN 280/20.  IT APPEARS THAT
THIS MORE RAPID MOTION MAY BE THE RESULT OF THE CIRCULATION CENTER
ROTATING WITHIN A LARGER CYCLONIC GYRE...OR PERHAPS THERE IS A
PROPAGATION COMPONENT TOWARD THE SHEARED CONVECTION.  IN EITHER
EVENT...I DO NOT EXPECT THIS RAPID MOTION TO PERSIST.  THE TRACK
FORECAST PHILOSOPHY IS UNCHANGED FROM THE PREVIOUS ADVISORY...AND
CALLS FOR FAUSTO TO MOVE WEST-NORTHWESTWARD TO THE SOUTH OF THE
SUBTROPICAL RIDGE.  THE ECMWF IS AN INTERESTING OUTLIER...
THOUGH...TAKING FAUSTO ABOUT 300 NM TO THE NORTHWEST OF THE OTHER
MODELS BY 5 DAYS.  THIS APPEARS TO BE DUE TO THE FORECAST
AMPLIFICATION OF A MID-LEVEL VORTICITY MAX CURRENTLY OVER EXTREME
WESTERN TEXAS AS IT MOVES WESTWARD TOWARD THE BAJA PENINSULA.  THIS
FEATURE THEN PLAYS A ROLE IN BREAKING DOWN THE SUBTROPICAL RIDGE
WEST OF BAJA IN ABOUT 3-4 DAYS.  THE EVOLUTION OVER THE COLD WATERS
WEST OF BAJA IN PARTICULAR SEEMS UNREALISTIC...SO FOR THE
MOMENT...THIS SCENARIO IS BEING DISCOUNTED.  

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0300Z 11.8N 101.7W    40 KT
 12HR VT     17/1200Z 12.2N 104.0W    45 KT
 24HR VT     18/0000Z 12.9N 106.3W    50 KT
 36HR VT     18/1200Z 13.5N 108.4W    55 KT
 48HR VT     19/0000Z 13.9N 110.2W    60 KT
 72HR VT     20/0000Z 15.0N 113.0W    65 KT
 96HR VT     21/0000Z 16.5N 116.5W    70 KT
120HR VT     22/0000Z 18.0N 121.0W    65 KT
 
$$
FORECASTER FRANKLIN
 
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