

262 

AGPN40 KWNM 061508

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

808 AM PDT SAT AUG 6 2016



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

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



A 1034 MB HIGH PRES CENTER REMAINS STATIONED WELL OFFSHORE NEAR

45N145W PER THE 12Z OPC SFC ANALYSIS. A 1012 MB LOW IS ANALYZED

JUST N OF THE PZ5 WTRS...A WEAK SFC REFLECTION OF AN UPR LOW

LOCATED OVER VANCOUVER ISLAND THIS MORNING. THE PRES GRADIENT

CONTINUES TO RELAX ALONG THE W COAST AS THIS UPR LOW...AS WELL AS

A SHORTWAVE TROF OVER THE OUTER PZ6 WTRS...HELP TO WEAKEN THE

INFLUENCE OF THE OFFSHORE RIDGE. EARLIER ASCAT PASSES INDICATED

WIND SPEEDS HAVE DIMINISHED TO 15-25 KT ACROSS THE OFFSHORE

WTRS...AND THE MODELS AGREE THAT THIS TREND WILL CONTINUE THRU

TONIGHT. THEREFORE...NO NOTABLE CHANGES TO THE FCST PACKAGE THIS

MORNING.



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PREVIOUS DISCUSSION...



THE 06Z NCEP SFC ANALYSIS SHOWS A 1035 MB HIGH NEAR 45N145W WITH

N TO NW FLOW PREVAILING ACROSS THE OFFSHORE AND CSTL WTRS. A HIGH

RES ASCAT-B PASS FM 0445Z RETURNED N TO NW WINDS 15 TO 20 KT EXCP

OVER THE E PORTIONS OF NRN CA AND SRN OREGON WTRS 20 TO 25 KT

WHERE EARLIER THERE WERE 30 KT RETURNS NR SRN OREGON CST. A TROF

EXTENDS ALG BC COAST NW FM VANCOUVER ISL WITH AN APRNT LOW IN

ASCAT DATA IN QUEEN CHARLOTTE SOUND. SWATH OF NW 25 TO 30 KT IS W

OF TROF MAINLY W AND S OF QUEEN CHARLOTTE ISL. ADDNLY ASCAT

CAPTURED AREA OF CHANNELED WINDS TO 25 KT NR PT CONCEPTION. BASED

ON THESE PASSES AND LIMITED SHIP DATA...THE 00Z GFS 10M WINDS

APPEAR TO HAVE INITIALIZED WELL AND APPEAR REPRESENTATIVE FOR

START OF FCST TODAY.



THE 00Z GFS/ECMWF/UKMET REMAIN IN VERY GOOD AGREEMENT THRU THE

FCST PERIOD. GOES15 WV IMAGERY REVEALS A MID/UPR LOW NR N END OF

VANCOUVER ISL AND ALSO A S/W TROF APPROACHING THE NRN CA OFSHR

AREA FROM THE W. THE MODELS APPR WELL INITIALIZED AND AGREE THESE

FEATURES WILL WEAKEN THE OFFSHORE RIDGE AND RELAX THE PRES

GRADIENT THRU THIS WEEKEND...DIMINISHING WIND SPEEDS TO 15-20 KT

OVER THE CA WTRS WITH EVEN WEAKER WINDS OVER THE INNER OR/WA WTRS

CLOSER TO TRACK OF THE UPR LOW AND ASCD WK SFC LOW OR TROF. AS

THE UPR LOW TURNS EWD INLAND OVER WA SUN NIGHT INTO MON...THE UPR

RIDGE W OF THE OFFSHORE WTRS STRENGTHENS...ALLOWING THE SFC HIGH

TO MOVE SE WITH A SFC RIDGE AXIS BUILDING ACROSS THE PZ5 WTRS BY

MON NIGHT. WIND SPEEDS OVER THE NRN/CENTRAL CA WTRS WILL INCREASE

MON INTO TUE AS THE GRADIENT TIGHTENS YET AGAIN ALONG THE W COAST.



GALES REMAIN A THREAT BY TUE AS THE 00Z MODELS LED BY THE GFS

STILL DEPICT 30-35 KT OVER THE NRN CA COASTAL AND POSSIBLY INNER

OFFSHORE WTRS AFFECTING AN AREA CENTERED ON PT ARENA WITH PZZ820

AND 825 AFFCTED. WITH THE BUILDING HIGH MAKING CLOSEST APCH TO

OFSHR WTRS ON TUE COUPLED WITH DPNG OF THERMAL TROF OVR CA...WILL

CONTINUE WITH USE OF A 30M/10M GFS BLEND FOR TUE. THIS YIELDS A

SMALL AREA OF GALES OVER INNER PORTIONS OF PZZ820/825. OTRW THE

00Z GFS 10M WINDS ARE PREFERRED MODEL CHOICE TODAY. WINDS THEN 

DIMINISH FAIRLY QUICKLY TUE NIGHT THRU WED AS HIGH PRES DRIFTS NW

AWAY FM THE AREA COUPLED WITH CONTINUED BUILDING NWD OF UPR

RDG...AND THE GRADIENT RELAXES.



.SEAS...USED THE 00Z ECMWF WAM INITIALLY AND THRU SUN MORNING WITH

ITS SEAS CLOSEST TO INITIAL ANALYSIS...THEN TRANSITIONED TO THE

00Z NWW3 FOR SUN THRU WED NIGHT...WHICH OVERALL WAS FAIRLY

CONSISTENT WITH THE WAM BUT GENERATED HIGHER SEAS WITH THE GALES

ON TUE.



.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 POSSIBLE TUE.

.PZZ825...INNER WATERS FROM POINT ARENA TO PIGEON POINT...

     GALE POSSIBLE TUE.



$$



.FORECASTER REINHART/BANCROFT. OCEAN PREDICTION CENTER.

