

088 

AGPN40 KWNM 280231

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

731 PM PDT WED JUL 27 2016



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

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



THE FOCUS OF THE FORECAST REMAINS ON THE INTERACTION BETWEEN THE

HEAT LOW/TROF OVER THE INTERIOR IN CENTRAL CAL AND STRONG HIGH

PRES W OF THE NRN CAL WTRS. THE STRONGEST PART OF THE PRES GRAD IS

TO THE W OF CAPE MENDOCINO AND PT ST GEORGE...AND ASCAT FM 19Z

INDC GALES JUST OFF THE COAST...WITH A LARGE AREA OF 30 KT

EXTENDING INTO OFSHR WTRS. IN ADDITION...WIND RETRIEVALS FM A 1830

UTC ALSO INDC 30 KT...WITH SEAS ABV 14 FT...SEVL FT HIGHER THAN

THE WAVE GUID. THE 18Z GFS INDC THE CRNT PTN WL CONT OVR PZ6 INTO

SUN...WITH GALES JUST OFF THE COAST UP TO THAT TIME. THE 12Z

ECMWF/UKMET/GEM/NAM ALL AGREE FAIRLY WELL WITH THE GFS ON THE

OVERALL PTTN...AND ALL INDC GALE OR NEAR GALE FORCE WINDS INTO

SUN. THE PREV FCST HAD GALES CONSISTENT WITH THE GFS...AND CONFDC

IS MDT TO HIGH WITH THEM...SO PLANNING ON MAINTAINING PREV WRNG IN

NE PZ6/SE PZ5 IN UPDATE PKG.



ALSO...THE LTST GOES IR/VIS IMGRY INDC A STG LOW PRES SYS CENTERED

OVER THE GULF OF ALASKA....WITH A FRONTAL BNDRY EXTENDING TO THE S

THEN SW FROM THE LOW. THE IMGRY ALSO INDC A WK FRNTL WAVE CRNTLY

NR 44N149W...MOVG TO THE E TWD NRN PZ5. THE MDLS AGREE FAIRLY WELL

ON MOVING THE WK WAVE INTO NRN PZ5 THU NGT INTO FRI AND DSIPT. THE

GFS INDC THE WK CD SURGE WL ACT TO LOWER STATIC STABILITY OVR

PZ5...ALLOWING STGR WINDS ALOFT TO MIX DN. THE MDLS ALL INDC WINDS

TO 40 KT OVR THE NE WAS WTRS BY LATE FRI INTO SAT...SO THE

POTENTIAL FOR GALES TO MIX DN IS THERE. ALSO...THE MDLS INDC A

SECOND SFC TROF WL DEVELOP ALONG THE COAST OF WAS AND EXTEND OVER

VANCOUVER ISLAND...AND INTERACT WITH THE AFOREMENTIONED HIGH W OF

THE AREA. AS A RESULT...CONFDC IS MDT TO HIGH WITH GALES OVER

PZZ800 FRI NIGHT INTO SAT NIGHT...SO PLANNING ON KEEPING PREV

WARNING IN UPDATE PKG.



OTRW...THE 12Z/18Z GFS HAS BEEN CONSISTENT WITH THE OVERALL PTTN

OVER THE PAST FEW DAYS...AND INDC ANOTHER WK CD FNT WL MOV INTO

NRN PZ5 MON. THE 12Z UKMET/GEM ARE SLIGHTLY FASTER THAN THE GFS

WITH THE PROGRESSION OF THE FRONT...AND THE 12Z ECMWF IS SLOW

OUTLIER. THE GFS WAS FAVORED IN THE PREV FCST...AS IT WAS THE BEST

COMPROMISE...SO PLANNING ON STAYING WITH IT FOR THE REMAINDER OF

THE UPDATE PKG.



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

PREVIOUS DISCUSSION...



THE ENHANCED PRES GRADIENT PERSISTS OVER THE NRN CA/SRN OR WATERS

THIS AFTN PER THE 18Z OPC SFC ANALYSIS. STRONG NLY FLOW CONTINUES

BETWEEN A 1030 MB HIGH W OF THE WATERS AND A 1010 MB THERMAL LOW

ANALYZED OVER NRN CA. A 1757Z ASCAT PASS REVEALED A LARGE SWATH OF

20-30 KT WINDS EXTENDING FROM THE SRN PZ5 WATERS INTO THE NRN AND 

CENTRAL PZ6 WATERS...WITH A FEW GALE BARBS NOTED IN THE COASTAL

WATERS W OF THE CA/OR BORDER.



THE 12Z MODELS CONTINUE TO DEPICT AN EXTENDED PERIOD OF GALES

BEGINNING OVER THE NRN CA WATERS LATER THIS AFTN...EXPANDING INTO

THE FAR SE OR WATERS ON FRI AS THIS PATTERN PERSISTS FOR THE NEXT

FEW DAYS. POPULATED WITH A BLEND OF THE 10/30M GFS WINDS THRU SAT

TO ACCOUNT FOR THE 10M GFS/ECMWF WINDS RUNNING A BIT TOO LOW AS

NOTED IN THE PREVIOUS FCST. THEN TRANSITIONED TO THE 10M GFS WINDS

THROUGH MON NIGHT...WHICH REFLECTS LOWERED CONFIDENCE FOR GALES

LATER IN THE PERIOD AND MATCHES UP WELL WITH THE 12Z ECMWF AND OUR

NEIGHBORING WFOS. AS A WEAK AREA OF LOW PRES RIDES OVER THE SFC

RIDGE SUN THRU EARLY MON...SFC HIGH PRES WILL WEAKEN AND THE

GRADIENT SHOULD RELAX ENOUGH FOR THESE GALES TO SUBSIDE BY SUN

NIGHT.



A SECOND AREA OF GALES IS EXPECTED TO DEVELOP OVER THE NE WA

WATERS LATE FRI/EARLY SAT. THE 12Z GFS/ECMWF SHOW ANOTHER SFC

TROUGH DEVELOPING OVER THE NRN PZ5 WATERS FRI INTO SAT...WITH

ENHANCED N/NW FLOW PRIMARILY BETWEEN 00Z-12Z SAT OVER THE NE

PORTION OF PZ800. THERE WAS ENOUGH SUPPORT WITH THE 12Z GUIDANCE

TO WARRANT KEEPING THIS BRIEF PERIOD OF GALES IN THE FCST ATTM.



.SEAS...A JASON-2 ALTIMETER PASS FROM 1828Z INDICATES THAT BOTH

THE NWW3 AND ECMWF WAM GUIDANCE ARE STILL RUNNING 1-2 FT TOO LOW

WITHIN THE STRONG NLY FLOW OFF NRN CA. USED PREVIOUS WAVE GRIDS

FOR THE NEAR TERM AND MANUALLY EDITED THEM TO BOOST SEAS AND REFLECT

THE 14 FT MAX SHOWN IN THE LATEST ALTIMETER DATA. THEN POPULATED

WITH THE 12Z NWW3 THU THROUGH MON NIGHT TO MATCH THE WIND GRIDS.



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





.WARNINGS...PRELIMINARY.



.PZ5 WASHINGTON/OREGON WATERS...

.PZZ800...INNER WATERS FROM CAPE FLATTERY TO CAPE SHOALWATER...

     GALE POSSIBLE FRI NIGHT.

     GALE POSSIBLE SAT NIGHT.

.PZZ815...INNER WATERS FROM FLORENCE OR TO POINT ST. GEORGE...

     GALE FRI.

     GALE POSSIBLE FRI NIGHT.



.PZ6 CALIFORNIA WATERS...

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

     GALE TONIGHT INTO FRI. 

     GALE POSSIBLE FRI NIGHT INTO SUN. 

.PZZ920...OUTER WATERS FROM POINT ST. GEORGE TO POINT ARENA...

     GALE POSSIBLE FRI NIGHT.



$$



.FORECASTER KELLS/REINHART. OCEAN PREDICTION CENTER.

