WTPA44 PHFO 190905
TCDCP4

TROPICAL STORM GUILLERMO DISCUSSION NUMBER  29
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP102009
1100 PM HST TUE AUG 18 2009

GUILLERMO APPEARS TO BE HANGING ON FOR DEAR LIFE DESPITE NEARLY 40
KNOTS OF SHEAR ANALYZED OVER IT IN THE CIMSS VERTICAL SHEAR
ANALYSIS. A BURST OF NEW CONVECTION OCCURRED ON THE NORTHWEST SIDE
OF GUILLERMO OVER THE PAST FEW HOURS...BUT THE PRESENTATION OF THE
LOW CLOUD FIELD IN INFRARED IMAGERY APPEARS TO HAVE GRADUALLY
DEGRADED. A 0442Z QUIKSCAT PASS IS THE BASIS FOR MAINTAINING
GUILLERMO AS A 35 KT TROPICAL STORM IN THIS ADVISORY PACKAGE. 

GUILLERMO IS CURRENTLY OVER SEA SURFACE TEMPERATURES OF ABOUT 26
DEGREES CELSIUS AND IS EXPECTED TO REMAIN OVER MARGINALLY WARM
WATER FOR THE NEXT THREE DAYS. GLOBAL MODELS ARE IN GOOD AGREEMENT
THAT THE SHEAR WILL CONTINUE TO WEAKEN OVER THE NEXT 24 HOURS AS
GUILLERMO MOVES UNDERNEATH THE TROUGH AXIS. AFTER 24 HOURS...THE
SHEAR REINTENSIFIES FROM A NORTHERLY DIRECTION. MOST OF THE
INTENSITY GUIDANCE RESPONDS BY MAINTAINING GUILLERMO AS A TROPICAL
STORM A LITTLE LONGER THAN PREVIOUSLY. WE HAVE SLOWED THE RATE OF
WEAKENING SLIGHTLY WITH THIS FORECAST PACKAGE.

THE INITIAL MOTION IS 310/16. GUILLERMO IS LOCATED TO THE
SOUTH-SOUTHWEST OF A LARGE 1028 MB HIGH OVER THE EASTERN NORTH
PACIFIC. THE DYNAMICAL MODELS KEEP GUILLERMO ON A NORTHWESTWARD
MOTION FOR THE NEXT 36 HOURS. BEYOND 36 HOURS...THE GUIDANCE
SPREAD INCREASES SIGNIFICANTLY...WITH SOME OF THE GUIDANCE
INCLUDING THE UKMET AND NOGAPS SUGGESTING SLOWING...THEN
RECURVATURE...WHILE THE GFS AND ECMWF SUGGEST THAT THE LOW LEVEL
CIRCULATION WILL CONTINUE FARTHER WESTWARD BEFORE DISSIPATING. THE
OFFICIAL FORECAST TRACK HAS BEEN SHIFTED TO THE RIGHT IN A NOD TO
THE CONSENSUS...BUT REMAINS ON THE LEFT SIDE OF THE GUIDANCE
SPREAD.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/0900Z 29.1N 153.5W    35 KT
 12HR VT     19/1800Z 30.5N 155.6W    35 KT
 24HR VT     20/0600Z 32.1N 158.4W    30 KT
 36HR VT     20/1800Z 33.2N 160.8W    30 KT
 48HR VT     21/0600Z 34.0N 163.2W    30 KT
 72HR VT     22/0600Z 34.9N 166.3W    25 KT...DISSIPATING
 96HR VT     23/0600Z...DISSIPATED
 
$$
FORECASTER R BALLARD