

230 

AGPN40 KWNM 040332

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

832 PM PDT WED AUG 3 2016



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

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



PERSISTENT PATTERN CONTS OVER THE NE PAC WITH STNRY STRONG HIGH

PRES NEAR 45N 148W WITH RIDGING INTO NRN WTRS ACTING AGAINST A

THERMAL TROF FM INLAND CA TO SW OREGON. A COMAPRISON OF LATEST

SHIP OBS AND EARLIER MORNING ASCAT PASSES INDICATE A BLEND OF 12Z

GFS 10M WITH 30M WINDS LOOKS REPRESENTATIVE...AND CURRENT GRIDS

ARE BASED ON THIS BLEND WEIGHTED 75 PCT IN FAVOR OF 30M WINDS.

QUESTION REMAINS ON WHETHER GALES BETWEEN CAPE BLANCO AND PT ARENA

MAINLY IN PORTIONS OF CSTL WTRS EXTEND INTO OFSHR WTRS. THE 18Z

GFS CAME IN A BIT WEAKER WITH BL WINDS AND DOES NOT SPRT GALES

EXTENDING INTO OFSHR WTRS. WITH A 00Z SHIP REPORT NEARBY WITH N 30

KT W OF PT ST GEORGE AT BOUNDARY WITH CSTL WTRS AND TIGHTER

GRADIENT TO S AND E PREFER THE STRONGER 12Z GFS BL WINDS AND WITH

THERMAL TROF TENDING TO STRENGTHEN DIURNALLY INTO EVENING WILL

LEAVE GALES IN PLACE OVERNIGHT INTO EARLY THU...WITH 12Z ECMWF AS

WELL AS 12Z GFS KEEPING A WIND MAX OFF NRN CA IN INNER ZONE INTO

THU MRNG.



WILL LEAVE REMAINDER OF FCST UNCHANGR=ED FOR NEW AS LATEST MDLS

HAVING THE RIGHT TRENDS GOING TO SUBGALE THU AND BEYOND. WILL NEED

TO WATCH TOWARD DAY 5 WHEN UPR LOW MOVG OVR PAC NW DEPARTS

ALLOEING UPR RDG TO BUILD IN EARNEST TOWARD THE WTRS. CURRENT FCST

BASED ON 12Z ECMWF IS SIMILAR TO 12Z GFS 10M WINDS...BUT IF 12Z

ECMWF WINDS ARE BOOSTED IT LEADS TO GALES EXTENDING INTO OFSHR

WTRS. POSSIBILITY OF GALES LATER MON AND MON NIGHT WILL BE

REVISITED LATER WITH LATER MDL CYCLES.



SEAS...CURRENT WAVE HEIGHT GRIDS BASED ON 12Z NWW3 APPR WELL

INITIALIZED COMPARED TO 00Z SEA STATE ANALYSIS EXCP WITH 10 PCT

BOOST WITH GALE AREAS...AND NO CHANGES APPR NEED AT THIS TIME.

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

PREVIOUS DISCUSSION...



THE 18Z OPC SFC ANALYSIS INDICATES THE PRES GRADIENT ALONG THE W

COAST REMAINS PINCHED THIS AFTN BETWEEN A STNRY 1040 MB HIGH PRES

CENTER NEAR 44N147W AND A 1012 MB LOW/THERMAL TROUGH OVER NRN CA.

A RECENT ASCAT PASS FROM 1805Z SHOWS A BROAD AREA OF 20-30 KT NLY

WINDS OVER THE SRN OR/NRN CA WATERS...HIGHEST WITHIN THE E PORTION

OF THE INNER NRN CA OFFSHORE ZONE FROM PT ST GEORGE TO PT ARENA.



THE 12Z GFS/ECMWF RUNS CONTINUE TO INDICATE THE POTENTIAL FOR

GALES OVER THE NE PORTION OF PZ820 BEGINNING AFTER 00Z THU. WHILE 

THE STRONGEST WINDS WILL LIKELY REMAIN OVER THE COASTAL WTRS...

OFFSHORE HIGH PRES WAS ANALYZED SLIGHTLY STRONGER THAN THE MODELS

WERE PREVIOUSLY INDICATING...AND IT IS EXPECTED TO REMAIN STNRY

THRU TONIGHT INTO THU. THEREFORE...CONFIDENCE WAS HIGH ENOUGH TO

MAINTAIN MARGINAL GALES FOR PZ820. FURTHERMORE...BOTH THE 12Z

GFS/ECMWF DEPICT A FAIRLY SHARP INLAND TROUGH OVER NRN CA UNTIL

18Z THU...AND THE MODEL WIND FIELDS HINT AT A SECONDARY SPEED MAX

OVER OUR WTRS AROUND 12Z THU WITH THE STRONG HIGH REMAINING STNRY.

THEREFORE...HAVE EXTENDED THE GALE WARNING FOR PZ820 INTO THU

MORNING WITH THIS ISSUANCE.



AN UPPER LOW CURRENTLY OVER THE ERN GULF OF AK WILL MOVE SE OVER

THE NEXT COUPLE DAYS...NEARING VANCOUVER ISLAND BY FRI MORNING.

THIS FEATURE WILL HELP WEAKEN THE OFFSHORE RIDGE AND RELAX THE

PRES GRADIENT ALONG THE W COAST THROUGH THE WEEKEND. SO AFTER 18Z

THU...DO NOT ANTICIPATE ANY GALES OVER THE OFFSHORE WTRS THRU MON

NIGHT.



THE 12Z GFS WAS THE MODEL OF CHOICE FOR MOST OF THE PERIOD.

STARTED WITH A BLEND OF THE 30M/10M WINDS THRU THU MORNING TO

PRODUCE THE SMALL AREA OF GALES DETAILED ABOVE. THEN USED THE GFS

10M WINDS THRU 18Z SUN. TRANSITIONED TO THE 12Z ECMWF AFTER 18Z

SUN AS THIS SOLUTION GENERATED SLIGHTLY STRONGER WINDS OVER THE

PZ5 WATERS INTO MON...WHICH MATCHED UP BETTER WITH THE 12Z UKMET.



.SEAS...THE 12Z NWW3 WAS USED THRU SUN MORNING WITH A 10 PCT WAVE

HGT BOOST IN THE NEAR TERM TO ACCOUNT FOR THE MODELS RUNNING

SLIGHTLY LOW WITH GALES IN THE FCST. THEN POPULATED WITH THE 12Z

WAM SUN THROUGH MON NIGHT TO REMAIN CONSISTENT 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 TONIGHT INTO THU. 



$$



.FORECASTER BANCROFT/REINHART. OCEAN PREDICTION CENTER.

