750
WTPA44 PHFO 030916
TCDCP4
HURRICANE GUILLERMO DISCUSSION NUMBER 18
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092015
1100 PM HST SUN AUG 02 2015
LATEST SATELLITE IMAGERY CONTINUES TO SHOW DEEP CONVECTION
STRUGGLING TO MAINTAIN ITSELF OVER THE LOW LEVEL CIRCULATION CENTER
GUILLERMO DUE TO THE INCREASING WESTERLY WIND SHEAR THE SYSTEM IS
ENCOUNTERING. THE U.S. 53RD WEATHER RECONNAISSANCE AIRCRAFT
CONFIRMED THAT THE SYSTEM IS WEAKENING WHILE SAMPLING THE INNER CORE
OF GUILLERMO THIS EVENING...WITH NO FLIGHT LEVEL OR SURFACE WINDS OF
64 KNOTS OR GREATER FOUND. THE CENTRAL PRESSURE OF THE SYSTEM HAD
RISEN TO AROUND 990 MB AS WELL. ADDITIONALLY...DVORAK
CLASSIFICATIONS WERE 4.5/77KT FROM PHFO AND JTWC AND 4.0/65 KT FROM
SAB...WHILE FINAL T NUMBERS WERE LOWER AT 3.5 TO 4.0. FOR THE
INITIAL 0600Z INTENSITY WE USED 70 KNOTS WHICH FOLLOWED CLOSELY THE
DVORAK NUMBERS...BUT AS A RESULT OF THE AIRCRAFT SAMPLING OF
GUILLERMO THE 0900Z INITIAL INTENSITY WILL BE ADJUSTED DOWNWARD TO
65 KNOTS.
THE INITIAL MOTION IS TOWARD THE WEST-NORTHWEST...OR 300 DEGREES...
AT 9 KT. A LOW LEVEL RIDGE SITS ABOUT 1500 NM TO THE NORTHWEST OF
GUILLERMO...WHILE A NORTH PACIFIC UPPER LEVEL TROUGH HAS CARVED OUT
A WEAKNESS IN THE MID TO UPPER LEVEL RIDGE JUST NORTH OF THE
HURRICANE. GUILLERMO WILL CONTINUE TO MOVE ON A SIMILAR BEARING FOR
THE NEXT FEW DAYS INTO THE WEAKNESS ALOFT...TAKING THE SYSTEM NEAR
OR POSSIBLY OVER THE HAWAIIAN ISLANDS ON WEDNESDAY AND THURSDAY.
THE TRACK FORECAST HAS BEEN CHANGED LITTLE FROM THE LAST ADVISORY
AND REMAINS NEAR A RATHER TIGHT CLUSTER OF GFS...ECMWF...AND THE
CONSENSUS MODELS. THE TIGHT CLUSTERING OF THE MODELS THEN SHOWS
INCREASING SPREAD BETWEEN 48 HOURS AND 120 HOURS...LIKELY DUE TO
THE DIFFERING INTENSITY FORECASTS BY THE VARIOUS MODELS WITH
RESPECT TO THE SYSTEM.
THE LATEST UW-CIMSS VERTICAL WIND SHEAR ANALYSIS SHOWED 8 KNOTS
FROM 290 DEGREES...WHILE THE LATEST SHIPS ANALYSIS SHOWED 16 KNOTS
FROM 285 DEGREES. THIS IS LIKELY RESPONSIBLE FOR THE POOR
SATELLITE PRESENTATION AND THE WEAKENING OF THE SYSTEM SINCE THE
PREVIOUS ADVISORY. WEAKENING IS EXPECTED TO CONTINUE THROUGH THE
FORECAST PERIOD. AS GUILLERMO CONTINUES TO MOVE INTO THE BREAK IN
THE MID TO UPPER LEVEL RIDGE...OUTFLOW WITHIN THE NORTHWEST QUADRANT
WILL BECOME FURTHER DISRUPTED AND VERTICAL WIND SHEAR WILL
CONTINUE TO SLOWLY INCREASE. THE INTENSITY FORECAST CLOSELY FOLLOWS
THE ICON...WITH SHIPS PREDICTING MORE RAPID WEAKENING BEYOND 48
HOURS. THE FORECAST AND INITIAL WIND RADII WERE ADJUSTED BASED ON
THE AIRCRAFT DATA AS WELL.
AS GUILLERMO MOVES CLOSER TO HAWAII...WATCHES MAY BE ISSUED MONDAY
OR MONDAY NIGHT FOR PORTIONS OF THE STATE. HOWEVER...IT IS STILL TOO
SOON TO DETERMINE WITH CERTAINTY WHICH ISLANDS ARE MOST LIKELY TO
EXPERIENCE THE GREATEST IMPACTS FROM GUILLERMO. IT IS ALSO IMPORTANT
TO NOTE THAT SIGNIFICANT IMPACTS CAN EXTEND WELL AWAY FROM THE
CENTER.
ANOTHER RECONNAISSANCE AIRCRAFT MISSION INTO GUILLERMO IS
SCHEDULED FOR MONDAY MORNING. THE VALUABLE DATA TRANSMITTED IN
REAL-TIME FROM THESE MISSIONS WILL HELP US TO BETTER DETERMINE THE
LOCATION...INTENSITY AND SIZE OF THE HURRICANE. IN ADDITION...THE
NOAA G-IV JET IS SCHEDULED TO CONDUCT ANOTHER SYNOPTIC SAMPLING
MISSION AROUND GUILLERMO MONDAY AFTERNOON. THIS SAMPLING SHOULD HELP
IMPROVE THE MODEL INITIALIZATION OF GUILLERMO.
FORECAST POSITIONS AND MAX WINDS
INIT 03/0900Z 16.2N 145.4W 65 KT 75 MPH
12H 03/1800Z 16.8N 146.5W 60 KT 70 MPH
24H 04/0600Z 17.5N 148.1W 55 KT 65 MPH
36H 04/1800Z 18.1N 149.8W 50 KT 60 MPH
48H 05/0600Z 18.9N 151.5W 45 KT 50 MPH
72H 06/0600Z 20.5N 155.0W 40 KT 45 MPH
96H 07/0600Z 22.6N 158.9W 35 KT 40 MPH
120H 08/0600Z 24.5N 163.1W 30 KT 35 MPH
$$
FORECASTER JELSEMA/HOUSTON
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