000
WTPZ45 KNHC 160249
TCDEP5
HURRICANE GUILLERMO DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP102009
800 PM PDT SAT AUG 15 2009
 
GUILLERMO HAS MAINTAINED ITS CONVECTIVE VIGOR OVER THE PAST SEVERAL
HOURS AND...IF ANYTHING...HAS DEVELOPED A MORE SYMMETRIC CENTRAL
DENSE OVERCAST SINCE EARLIER THIS AFTERNOON.  A RATHER DISTINCT...
CLOUD-FILLED EYE IS ALSO OBSERVED...ALONG WITH A NUMBER OF
REASONABLY WELL-DEFINED BANDING FEATURES.  SINCE 1800 UTC...DVORAK
INTENSITY ESTIMATES HAVE INCREASED TO 5.0 FROM TAFB AND SAB AND
SUGGEST THAT THE OVERALL ORGANIZATION OF GUILLERMO HAS AT LEAST
PERSISTED. BASED UPON THESE DATA AND OBJECTIVE DVORAK ESTIMATES AS
HIGH AS 5.6 FROM UW CIMSS ADT ANALYSES...THE OFFICIAL INTENSITY IS
HELD AT 95 KT.
 
THE INITIAL MOTION IS ESTIMATED AT 290/13...REPRESENTING A SLIGHTLY
MORE WEST-NORTHWESTWARD MOTION SINCE EARLIER TODAY.  THE SYNOPTIC
REASONING BEHIND THE FORECAST REMAINS THE SAME.  GUILLERMO IS
CURRENTLY MOVING AROUND THE SOUTHWEST PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE EXTENDING FROM THE THE SOUTHERN UNITED STATES
WESTWARD IN THE EAST PACIFIC TO PAST 140W.  THIS WEATHER SYSTEM HAS
AND SHOULD CONTINUE TO KEEP GUILLERMO ON A STABLE...WEST-
NORTHWESTWARD TRACK THROUGH 48 HOURS. THEREAFTER...A RETROGRADING
MID- TO UPPER-LEVEL TROUGH IN THE VICINITY OF THE HAWAIIAN ISLANDS
SHOULD BEGIN TO INFLUENCE THE MOTION OF GUILLERMO BY IMPARTING A
SLIGHTLY MORE NORTHWARD COMPONENT OF MOTION. TOWARD THE END OF THE
PERIOD...THE LOW- TO MID-LEVEL FLOW SHOULD GUIDE A WEAKENING
GUILLERMO ON ESSENTIALLY THE SAME TRACK.
 
UNDER VERY LIGHT SHEAR...GUILLERMO HAS BEEN ABLE TO MAINTAIN ITS
INTENSITY IN SPITE OF MOVING OVER PROGRESSIVELY COOLER WATERS.
HOWEVER...THE CYCLONE SHOULD ENCOUNTER INCREASINGLY HOSTILE
SOUTHWESTERLY SHEAR WITHIN 24 HOURS AND EVEN COOLER SEA SURFACE
TEMPERATURES...WHICH SHOULD FINALLY RESULT IN A DECIDED WEAKENING.
THE OFFICIAL FORECAST IS AN UPDATE OF THE PREVIOUS ADVISORY AND IS
IN BEST AGREEMENT WITH ICON AND LGEM AND CLOSE TO THE FSU SUPER
ENSEMBLE...CALLING FOR GUILLERMO TO BECOME A REMNANT LOW BY DAY 4
AND TO DISSIPATE BY DAY 5.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0300Z 19.7N 135.9W    95 KT
 12HR VT     16/1200Z 20.3N 137.9W    80 KT
 24HR VT     17/0000Z 21.1N 140.5W    70 KT
 36HR VT     17/1200Z 22.0N 143.1W    55 KT
 48HR VT     18/0000Z 23.1N 145.9W    45 KT
 72HR VT     19/0000Z 25.5N 151.0W    35 KT
 96HR VT     20/0000Z 28.0N 156.5W    25 KT...REMNANT LOW
120HR VT     21/0000Z 30.5N 162.5W    20 KT...DISSIPATED
 
$$
FORECASTER KIMBERLAIN/AVILA