Tropical Storm PATRICIA

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TROPICAL STORM PATRICIA DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP192009
200 PM PDT MON OCT 12 2009
 
ALTHOUGH THE OVERALL CLOUD PATTERN ASSOCIATED WITH PATRICIA BECAME
BETTER ORGANIZED EARLIER TODAY...THE AMOUNT OF DEEP CONVECTION HAS
RECENTLY BEEN ON THE DECREASE.  IN ADDITION...A BANDING FEATURE
OBSERVED OVER THE SOUTHERN SEMICIRCLE HAS ALL BUT VANISHED DURING
THE PAST FEW HOURS.  IN SPITE OF THE VERY RECENT DEGRADATION IN THE
SATELLITE APPEARANCE OF PATRICIA...DVORAK T-NUMBERS AT 1800 UTC
WERE 3.5 FROM BOTH SAB AND TAFB.  BASED UPON THESE ESTIMATES...AS
WELL AS EARLIER QUIKSCAT AND ASCAT PASSES...THE INITIAL INTENSITY
IS BEING INCREASED TO 50 KT.

THE CENTER OF PATRICIA REMAINS CHALLENGING TO LOCATE...BUT
CONVENTIONAL AND MICROWAVE SATELLITE FIXES SUGGEST A LONGER-TERM
MOTION OF 325/07. PATRICIA IS BEING STEERED ON A NORTHWESTWARD TO
NORTH-NORTHWESTWARD COURSE AROUND THE WESTERN PERIPHERY OF A
DEEP-LAYER RIDGE EXTENDING WEST-SOUTHWESTWARD FROM THE GULF OF
MEXICO.  DYNAMICAL MODEL GUIDANCE INDICATES THAT THIS GENERAL
MOTION SHOULD CONTINUE FOR THE NEXT 24-36 HOURS...FOLLOWED BY AN
ABRUPT TURN TOWARD THE LEFT AS THE RIDGE OVER THE GULF OF MEXICO
BUILDS WESTWARD AND TO THE NORTH OF THE CYCLONE.  THE GFS AND
HWRF...WHICH WERE PREVIOUSLY MAINTAINING SOLUTIONS CLOSER TO THE
SOUTHERN BAJA CALIFORNIA PENINSULA...HAVE NOW SHIFTED TO THE WEST
AND ARE WITHIN THE SPREAD OF THE REMAINING MODELS.  THIS CHANGE
REPRESENTS PART OF A DEVELOPING TREND IN THE GUIDANCE TO TURN
PATRICIA ON A MORE WESTWARD TRACK...SOUTHWEST OF THE BAJA
CALIFORNIA PENINSULA.  THE OFFICIAL TRACK IS ADJUSTED TO THE LEFT
OF THAT FROM THE PREVIOUS ADVISORY...BUT NOT AS FAR LEFT AS THE
MODEL CONSENSUS AT THIS TIME.
 
IN AN ENVIRONMENT OF LIGHT EASTERLY SHEAR AND WARM SSTS...PATRICIA
HAS BEEN GRADUALLY STRENGTHENING DURING THE LAST 24 HOURS. 
HOWEVER...THE SHIPS MODEL OUTPUT CONTINUES TO INDICATE THE PRESENCE
OF A RELATIVELY DRY AND STABLE AIR MASS...WHICH IS ALSO IMPLIED BY
STRATOCUMULUS CLOUDS TO THE NORTHWEST OF THE CYCLONE.  THIS...ALONG
WITH THE ELONGATED NATURE OF THE CIRCULATION...WILL PROBABLY
PREVENT SIGNIFICANT STRENGTHENING.  THE OFFICIAL INTENSITY FORECAST
CALLS FOR ONLY SLIGHT INTENSIFICATION THROUGH 48 HOURS...FOLLOWED
BY A STEADY WEAKENING THROUGH THE FORECAST PERIOD AS PATRICIA MOVES
OVER PROGRESSIVELY COOLER WATERS TO THE WEST OF THE BAJA CALIFORNIA
PENINSULA.

SINCE THE TREND IN THE TRACK GUIDANCE HAS BEEN TO LESSEN THE THREAT
TO SOUTHERN BAJA CALIFORNIA...A HURRICANE WATCH IS NOT REQUIRED FOR
THAT AREA AT THIS TIME. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      12/2100Z 19.8N 110.1W    50 KT
 12HR VT     13/0600Z 20.7N 110.3W    55 KT
 24HR VT     13/1800Z 21.8N 110.5W    55 KT
 36HR VT     14/0600Z 22.3N 110.9W    60 KT
 48HR VT     14/1800Z 22.5N 111.9W    60 KT
 72HR VT     15/1800Z 22.5N 114.5W    50 KT
 96HR VT     16/1800Z 22.5N 117.0W    35 KT
120HR VT     17/1800Z 22.5N 120.0W    25 KT...REMNANT LOW
 
$$
FORECASTER KIMBERLAIN/PASCH
 
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