

432 

AGPN40 KWNM 170222

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

722 PM PDT TUE AUG 16 2016



.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT

.WEATHER FOR THE NORTH PACIFIC N OF 30N AND E OF 150W.



THE 18Z GFS WAS AGAIN VERY CLOSE TO THE PREVIOUS 12Z GFS...AS WELL

AS THE OTHER GLOBAL MODELS. WITH THIS IN MIND...WILL NOT BE MAKING

ANY MAJOR CHANGES FOR THE EVENING UPDATE. WILL ALSO NOT BE MAKING

ANY CHANGES TO THE EXISTING WARNING HEADLINES AS ALL THE MODELS

SEEM TO BE ON THE SAME PAGE KEEPING THE STRONGEST WINDS OVER THE N

CA OFFSHORE WATERS. THE 00Z SEA STATE ANALYSIS INDICATED THAT

OBSERVED SEAS MATCHED IP WELL WITH THE MWW3/ECMWF WAM FCST VALUES. 



-----------------------------------------------------------------

PREVIOUS DISCUSSION...



THE 18Z NCEP SFC ANALYSIS INDICATES 1030 MB HIGH PRES NEAR 40N140W

IS SLOWLY STRENGTHENING AS EXPECTED THIS AFTN. MEANWHILE A 1009 MB

LOW IS ANALYZED OVER NRN CA WITH A TROF EXTENDING NWD INTO SRN OR.

A 1744Z ASCAT-A PASS SHOWED 20 TO 30 KT NLY WINDS OVER THE NRN PZ6

WTRS WITH A SMALL POCKET OF GALES OVER THE COASTAL WTRS JUST S OF

CAPE BLANCO. THE 12Z GFS APPEARS TO HAVE INITIALIZED WELL AS IT

MATCHES UP CLOSELY WITH THIS WIND RETRIEVAL.



CONFIDENCE REMAINS HIGH FOR AN EXTENDED PERIOD OF GALES OVER THE

INNER OFFSHORE WTRS FROM PT ST GEORGE TO PT ARENA. THE 12Z RUNS OF

THE GFS/ECMWF/UKMET CONTINUE TO SUPPORT GALES REACHING THESE INNER

WTRS LATER TONIGHT AND PERSISTING THRU WED INTO WED NIGHT. THE

MODELS ALSO CONSISTENTLY DISPLACE THE AXIS OF STRONGEST WINDS

FURTHER S...NOT INCLUDING THE FAR SE PORTION OF THE PZ5 WTRS.

THEREFORE HAVE DECIDED TO DROP THE GALE WARNING FOR PZZ815 ATTM.

THIS FCST IS MORE CONSISTENT WITH THE ADJACENT COASTAL WTRS AS

WELL. GALES ALSO APPEAR LESS LIKELY WED NIGHT FOR THE NRN PZ5 WTRS

AS THE 12Z GFS/ECMWF/UKMET ONLY DEPICT WINDS REACHING 30 KT OVER

THESE WTRS. WILL NOT CARRY A GALE WARNING FOR PZZ800 ATTM AS

CONFIDENCE IS INCREASING ANY GALE FORCE WINDS DVLPG LATE WED WILL

REMAIN N OF OUR WTRS.



ONCE THE NRN CA GALES SUBSIDE WED NIGHT...THE REST OF THE FCST

PERIOD APPEARS FAIRLY QUIET. HIGH PRES OFFSHORE WILL BEGIN TO

WEAKEN AND DRIFT W THU THRU SUN...RELAXING THE GRADIENT AS WIND

SPEEDS DIMINISH ESPECIALLY ACROSS THE PZ6 WTRS. WITH EXCELLENT

MODEL AGREEMENT AGAIN TODAY...THE 12Z GFS WAS HEAVILY UTILIZED TO

MAINTAIN CONTINUITY.



.SEAS...A WELL-PLACED JASON-2 ALTIMETER PASS AROUND 1425Z REVEALED

SEAS UP TO 13 FT ACROSS THE SRN PORTION OF PZZ820 EARLIER TODAY.

THIS WAS WITHIN A FT OF BOTH WAVE MODELS...SO JUST SOME MINOR HAND

EDITS WERE REQUIRED FOR THE NEAR TERM GRIDS. OTHERWISE THE 12Z

NWW3 WAS PREFERRED OVER THE 12Z ECMWF WAM AS IT BUILT SEAS FASTER

TONIGHT WITH THE ANTICIPATED GALES...AND MATCHED UP BETTER WITH

THE ADJACENT COASTAL WTRS. EXPECT SEAS WILL BUILD TO 16 FT TMRW

OVER THE INNER NRN PZ6 WTRS WITH THE PERSISTENT GALES.





.EXTRATROPICAL STORM SURGE GUIDANCE...N/A.







.WARNINGS...PRELIMINARY.



.PZ5 WASHINGTON/OREGON WATERS...

     NONE.



.PZ6 CALIFORNIA WATERS...

.PZZ820...INNER WATERS FROM POINT ST. GEORGE TO POINT ARENA...

     GALE TONIGHT INTO WED NIGHT. 



$$



.FORECASTER KOSIER/REINHART. OCEAN PREDICTION CENTER.

