Tropical Storm PATRICIA

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TROPICAL STORM PATRICIA DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP192009
800 AM PDT TUE OCT 13 2009

PATRICIA LOOKS SOMEWHAT DISORGANIZED THIS MORNING.  THE CENTRAL
DENSE OVERCAST IS RAGGED AND ELONGATED NORTH TO SOUTH...AND NO OUTER
BANDING IS PRESENT.  THE OVERALL CIRCULATION ALSO APPEARS TO BE
ELONGATED FROM NORTH TO SOUTH.  IN ADDITION...THE CIRRUS OUTFLOW IS
POOR IN ALL DIRECTIONS.  SATELLITE INTENSITY ESTIMATES ARE 55 KT
FROM TAFB AND 45 KT FROM SAB...SO THE INITIAL INTENSITY REMAINS A
POSSIBLY GENEROUS 50 KT.

THE STORM HAS CONTINUED TO MOVE EAST OF DUE NORTH DURING THE PAST
SEVERAL HRS...WITH THE INITIAL MOTION ESTIMATED AT 015/6.  THE LARGE
SCALE MODELS FORECAST THE LARGE MID/UPPER-LEVEL TROUGH OVER THE
WESTERN UNITED STATES TO LIFT OUT...WITH AN EAST TO WEST MID-LEVEL
RIDGE DEVELOPING NORTH OF PATRICIA DURING THE NEXT 12-36 HR.  THESE
DEVELOPMENTS SHOULD TURN THE CYCLONE NORTHWESTWARD AND WESTWARD
DURING THE FORECAST PERIOD...AS INDICATED BY ALL THE DYNAMICAL
GUIDANCE EXCEPT THE HWRF.  THAT MODEL FORECASTS PATRICIA TO MOVE
NORTHWESTWARD ALONG THE WEST COAST OF BAJA CALIFORNIA...WHICH
APPEARS UNLIKELY AT THE MOMENT.  THE NEW FORECAST TRACK FOLLOWS THE
TREND OF THE PREVIOUS FORECAST AND CALLS FOR A TURN TOWARD THE
NORTHWEST DURING THE NEXT 12-24 HR...WITH A WESTWARD MOTION LATER
IN THE FORECAST PERIOD.  THE NEW TRACK BRINGS THE CENTER CLOSER TO
SOUTHERN BAJA CALIFORNIA...WITH THE CLOSEST APPROACH DURING THE
FIRST 12-24 HR.
 
PATRICIA IS CURRENTLY IN A LIGHT VERTICAL WIND SHEAR ENVIRONMENT
OVER WARM WATER...SO THERE REMAINS THE POSSIBILITY OF
STRENGTHENING.  HOWEVER...UPPER-LEVEL WINDS APPEAR TO BE SOMEWHAT
CONVERGENT AT THIS TIME....AND TOTAL PRECIPITABLE WATER DATA SHOWS
VERY DRY AIR JUST WEST OF THE STORM.  THE LATTER SHOULD BECOME AN
INCREASING PROBLEM WHEN PATRICIA TURNS WESTWARD.  THE GLOBAL MODELS
FORECAST THE SYSTEM TO DISSIPATE WITHIN 72 HR...WHILE THE GFDL
HOLDS ON TO IT FOR FIVE DAYS WITH SOME STRENGTHENING DURING THE
FIRST 36 HR.  THE INTENSITY FORECAST COMPROMISES BETWEEN THESE
MODELS...WITH SLIGHT STRENGTHENING INDICATED DURING THE FIRST 12 HR
FOLLOWED BY GRADUAL DECAY TO DISSIPATION OVER COOLER SEA SURFACE
TEMPERATURES BY 96 HR.  THE HWRF CONTINUES TO FORECAST A
SIGNIFICANTLY STRONGER STORM AND REMAINS AN OUTLIER. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/1500Z 21.4N 109.0W    50 KT
 12HR VT     14/0000Z 21.9N 109.3W    55 KT
 24HR VT     14/1200Z 22.3N 110.3W    50 KT
 36HR VT     15/0000Z 22.4N 111.8W    45 KT
 48HR VT     15/1200Z 22.5N 113.3W    40 KT
 72HR VT     16/1200Z 22.5N 116.5W    30 KT
 96HR VT     17/1200Z 22.5N 119.5W    20 KT...REMNANT LOW
120HR VT     18/1200Z...DISSIPATED
 
$$
FORECASTER BEVEN
 
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