

113 

AGPN40 KWNM 030333

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

833 PM PDT TUE AUG 2 2016



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

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



A HIGH PRES AREA REMAINS STNRY NEAR 44N 146W W OF OREGON OFSHR

WTRS. A MID LVL/UPR LOW HAS MOVD INLAND OVR WA/SRN BC WITH AN ASCD

SFC TROF EXTENDING SW OVR WA INNER WTRS. UPR LOW AND SFC TROF MOVG

INLAND WILL ALLOW SOME BUILDING OF UPR AND SFC RDG INTO THE OFSHR

WTRS FM THE W TONIGHT INTO WED NIGHT BEFORE THE NEXT UPR LVL LOW

ARRIVES FM THE NW. HAVE NO RECENT ASCAT OR RAPIDSCAT IMAGERY

COVERING AREAS OF INTEREST INCLUDING SUSPECTED NLY GALES OFF CST S

OF CAPE BLANCO TO PT ARENA. SEE SOME EVIDENCE OF GALES FM BUOY

46027 OFF PT ST GEORGE REPORTING N 31G37 LAST FEW HRS. ALSO

RECEIVED A 00Z SHIP REPORT FARTHER OFSHR NEAR 38N 127W AND ANOTHER

OVR INNER NRN CA OFSHR WTRS NR 40N 126W WITH NW 30 KT AT 21Z. HAVE

MADE SOME EDITS NEAR TERM BOOSTING THE WINDS BY 10 PCT OVERNIGHT

AND WED MORNING MORE IN LN WITH THE 75 PCT 12Z GFS 30M PREFERRED

IN CURRENT PACKAGE AFTER 15Z WED...WITH RESULTING WIND GRIDS MORE

CLOSELY MATCHING OBS. 



OTRW LATEST MDL GUIDANCE REMAINS IN GOOD AGRMT WITH THIS SLOWLY

EVOLVING SUMMERTIME PATTERN OF PERSISTENT NLY FLOW OVR THE WTRS.

CURRENTLY SHOW GALES AFFECTING ONLY CST WTRS BUT PER LATEST

GUIDANCE HALE MDT CONFDC THAT EPAC RIDGE WILL BUILD ENUF

COMBINED WITH STRENGTHENING OF THERMAL TROF INLAND WED INTO WED

NIGHT TO SPRT SOME EXPANSION OF NLY GALES INTO ADJ INNER NRN CA

WTRS...ZONE PZZ820. ATTM THERE IS LTL SPRT FOR GALES AFTER WED

NIGHT AS ANOTHER UPR LVL SYSTEM...NOW IN NRN GLF OF AK...DROPS SE

ON E SIDE OF UPR RDG TO NR VANCOUVER ISL THU NIGHT AND WA COAST

FRI INTO SUN WHICH WILL TEND TO WKN THE HIGH PRES RDG OFSHR. WILL

MAKE NO OTHER CHANGES TO CURRENT PACKAGE.



SEAS...CURRENT SEA STATE GRIDA APPR WELL INITIALIZED COMAPEED TO

00Z SEA STATE ANALYSIS. THERE ARE ONLY MINOR DIFFERENCES INWAVE

GUIDANCE DURING PERIOD SO PREVIOUSLY USED 50/50 BLEND OF THE 12Z

WAVE MDLS LOOKS RSNBL.

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

PREVIOUS DISCUSSION...



A NEARLY STATIONARY 1037 MB HIGH REMAINS CENTERED W OF THE FCST

WATERS AROUND 45N146W PER THE 18Z OPC SFC ANALYSIS. STRONG NLY

FLOW PERSISTS OFF THE NRN CA COAST THIS AFTN WHERE THE GRADIENT

REMAINS PINCHED BETWEEN THIS HIGH AND AN INLAND TROUGH. NO LUCK

WITH THE ASCAT PASSES THIS AFTN AS BOTH SWATHS MISSED THE AREA OF

STRONGEST WINDS OFF NRN CA. A 1734Z PASS DID SHOW NLY WINDS OF

15-25 KT OVER THE CENTRAL CA WATERS WITH LIGHT NW FLOW IN THE SRN

CA ZONES. THE WEAK SFC LOW THAT WAS LOCATED JUST N OF THE WA

WATERS THIS MORNING HAS SINCE DISSIPATED.



A FAIRLY TYPICAL SUMMER PATTERN WILL PERSIST ALONG THE W COAST

DURING THIS FCST PERIOD. HIGH PRES OFFSHORE WILL DRIFT W AND

STRENGTHEN THROUGH WED NIGHT...AND THE PRES GRADIENT WILL TIGHTEN

IN RESPONSE TO A SHARPENING INLAND TROUGH OVER NRN/CENTRAL CA.

THEREFORE...GALES APPEAR MOST LIKELY WED AFTN/NIGHT WITHIN THE

INNER NRN CA OFFSHORE WATERS. USED A 75/25 BLEND OF THE 30M/10M

GFS WINDS DURING THIS PERIOD TO MAINTAIN THESE GALES WITH MODERATE

CONFIDENCE. GALES SHOULD SUBSIDE BY EARLY THU MORNING...BUT 25-30

KT WINDS WILL PERSIST OVER THE SRN OR/NRN CA WATERS INTO FRI. THE

MODELS AGREE A SECONDARY TROUGH WILL DEVELOP OVER THE NRN PZ5

WATERS EARLY FRI...STRENGTHENING THE N-NW FLOW OVER THE NRN WA 

WATERS BUT REMAINING SUB-GALE.



THE WINDS SHOULD RELAX A BIT FRI THROUGH SUN AS OFFSHORE HIGH PRES

GRADUALLY WEAKENS. THE 12Z GFS MOVES THE HIGH FURTHER E THAN THE

12Z ECMWF/UKMET RUNS. ALTHOUGH THE WIND FIELD DIFFERENCES ARE

MINOR...TRANSITIONED TO THE ECMWF WINDS BEGINNING LATE SAT THROUGH

SUN NIGHT AS THIS SOLUTION WAS BETTER SUPPORTED BY THE UKMET.

OTHERWISE...THE 10M GFS WINDS WERE PREFERRED FOR MOST OF THE FCST 

OUTSIDE OF THE BRIEF PERIOD OF GALES DISCUSSED ABOVE.



.SEAS...WITH THE 12Z GFS/ECMWF WINDS MATCHING UP WELL THROUGH MOST

OF THE PERIOD...USED A 50/50 BLEND OF THE 12Z NWW3/WAM OUTPUT THROUGH

SAT. MANUALLY BOOSTED SEAS A BIT LATE WED INTO EARLY THU AS THE

MODELS APPEARED TOO LOW OFF NRN CA WITH GALES IN THE FCST. THEN

USED THE WAM GRIDS SAT NIGHT THROUGH SUN NIGHT TO MATCH UP WITH

THE FCST WINDS.



.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 WED INTO WED NIGHT. 



$$



.FORECASTER BANCROFT/REINHART. OCEAN PREDICTION CENTER.

