Tropical Storm Watch Issued

LITTLE HAS CHANGED THROUGH THE DAY WITH GUILLERMO LOOKING VERY
RAGGED IN THE SATELLITE IMAGES. DEEP CONVECTION HAS BEEN PULSING
NORTHEAST OF THE CENTER...WHICH HAS BEEN VERY DIFFICULT TO LOCATE
WITHOUT THE BENEFIT OF AIRCRAFT RECON. A VERY TIMELY AMSU PASS AT
0003 UTC WAS THE MAIN BASIS FOR THE INITIAL POSITION. SUBJECTIVE
DVORAK INTENSITY ESTIMATES FROM PHFO...SAB AND JTWC WERE ALL AT 55
KT AND IS THE INITIAL INTENSITY FOR THIS PACKAGE.
 
GUILLERMO IS MOVING THROUGH A BREAK IN THE RIDGE ALOFT WITH AN
INITIAL MOTION OF 310/09 KT. THE LATEST OBJECTIVE AIDS HAVE SHIFTED
FARTHER NORTH THAN THE PREVIOUS FORECAST WITH THE HWRF MAKING THE
LARGEST LEAP TO BECOME A NORTHERN OUTLIER THROUGH 36 HOURS. THE
CURRENT FORECAST IS AN UPDATE OF THE PREVIOUS PACKAGE AND IS CLOSE
TO THE GFS AND ECMWF TRACK THROUGH 36 HOURS...THEN SOUTH OF THE
DYNAMICAL AIDS FOR THE LATER FORECAST PERIODS. THIS FORECAST TRACK
ACCOUNTS FOR THE POSSIBILITY THAT THE INCREASING VERTICAL SHEAR
ALONG THE FORECAST TRACK COULD WEAKEN GUILLERMO A LITTLE FASTER THAN
THE DYANMICAL AIDS FORECAST AND WILL FOLLOW A PATH WEIGHTED MORE
TOWARD THE LOWER LEVEL STEERING CURRENT.
 
ALONG THE FORECAST TRACK...GUILLERMO WILL CONTINUE TO MOVE
TOWARD INCREASINGLY HOSTILE VERTICAL SHEAR. SHIPS SHEAR FORECASTS
INDICATE 25 KT BY 12 HOURS AND MORE THAN 30 KT BY 48 HOURS. THIS IS
CONSISTENT WITH UPPER LEVEL WINDS PROJECTED BY THE GLOBAL MODELS.
THE FORECAST CALLS FOR CONTINUED WEAKENING OF GUILLERMO AS IT
APPROACHES THE MAIN HAWAIIAN ISLANDS AND IS IN LINE WITH THE
PREVIOUS FORECAST.
 
WHILE THE FORECAST TRACK KEEPS THE CENTER OF GUILLERMO NORTHEAST OF
THE MAIN HAWAIIAN ISLANDS...A SIGNIFICANT DEVIATION TO THE LEFT OF
THE TRACK WOULD HAVE THE POTENTIAL TO BRING TROPICAL STORM
CONDITIONS TO THE BIG ISLAND OR MAUI COUNTY. WHEN ACCOUNTING
FOR THE SIZE OF THE SYSTEM...THERE REMAINS ENOUGH UNCERTAINTY TO
WARRANT ISSUANCE OF A TROPICAL STORM WATCH FOR HAWAII AND MAUI
COUNTIES. OTHER COUNTIES MAY BE ADDED LATER AS NEEDED.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  04/0300Z 18.1N 147.4W   55 KT  65 MPH
 12H  04/1200Z 18.8N 148.7W   50 KT  60 MPH
 24H  05/0000Z 19.8N 150.4W   45 KT  50 MPH
 36H  05/1200Z 20.6N 152.1W   45 KT  50 MPH
 48H  06/0000Z 21.5N 154.0W   40 KT  45 MPH
 72H  07/0000Z 23.5N 157.9W   35 KT  40 MPH
 96H  08/0000Z 25.5N 162.0W   30 KT  35 MPH
120H  09/0000Z 26.5N 166.5W   25 KT  30 MPH