

257 

AGPN40 KWNM 300337

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

837 PM PDT FRI JUL 29 2016



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

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



THE LAST MORNING ASCAT PASSES SHOWED LTL IN THE WAY OF GALE FORCE

WINDS OVR THE OFSHR AND CSTL WTRS...INSTEAD SHOWING NLY 20 TO 30

KT IN PZ5 WTRS AND A SOLID 25 TO 30 KT IN NRN CA WTRS. THESE CONDS

INDICATE CURRENT GRIDS BASED ON BLENDED GFS 10M AND 30M WINDS APPR

REPRESENTATIVE. SINCE THEN LATEST OBS INDICATE CONDS HAVE

INCREASED AS A SML CAA SURGE WORKS ITS WAY S INTO PZ5 WTRS

INCREASING THE CHANCE GALE FORCE WINDS WILL MIX DOWN. IN FACT

SHIP REPORTS WITH 35 KT APPR OFF VANCOUVER ISL AND OFF PT ST

GEORGE IN CSTL WTRS AT 00Z...AS THE INLAND THERMAL LOW PRES TROF

STRENGTHENS DIURNALLY. AS COLD SURGE CONTS TO MOV S AND AN UPR

SHRTWV TROF MOVS INLAND N OF AREA SHRTWV UPR RDG BLDS IN BEHIND IT

AND INCREASES GRADIENT IN NRN WTRS BETWEEN A TROF NR VANCOUVER ISL

AND AND SFC RDG BLDG FM W. LATEST MDLS SPRT EXPANSION OF GALES

TONIGHT INTO SAT NIGHT BOTH FM DIURNAL EFFCTS AND RDG BLDG FM W

WITH PSBL EXPANSION OF GALE OFF NRN CA INTO ADJ OUTER ZONE BUT

CONT TO HAVE HIGH CONFDC IN GALES FOR INNER ZONES OFF WA AND ALSO

SRN OREGON AND NRN CA.



AN UPR CLOSED LOW IS FCST BY MDLS TO APCH NRN WTRS FM WNW SAT

NIGHT INTO SUN NIGHT WHICH WILL WKN THE OFSHR HIGH PRES RDG FIRST

IN THE NRN WTRS SAT NIGHT...ENDING THE GALES THERE...AND THEN THE

CENTRAL PORTIONS INCUDING OREGON AND NRN CA SUN AND SUN NIGHT. UPR

AND SFC RDG REBUILD EWD AFTER UPR LOW MOVS INLAND MON NIGHT INTO

TUE. THIS WL LKLY INCREASE GRADIENT ENUF TO REDVLP NLY GALES AT

LEAST OVR NRN CA INNER WTRS TUE NIGHT INTO WED NIGHT.



FOR THE EVENING UPDATE THE CURRENT FCST GRIDS LOOK RSNBL ALG WITH

ASCD WAVE GRIDS BASED ON CONSISTENT AND REPRESENTATIVE GFS AND ENP

WW3 GUIDANCE...WITH 12Z ECMWF WAVE GUIDANCE SIMILAR.

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

PREVIOUS DISCUSSION...



THE SAT IMG INDC FAIRLY CLOUDY SKIES ACROSS THE REGION BUT ALMOST

NO REPORTS OF LIGHTNING STRIKES. ALL THE OBSERVATIONS INDC HIGHER

WINDS OVER THE NRN CAL AND SRN OREG WATERS. AT 18Z INLAND TROF

EXTENDS NW FROM LOW PRES OVER SRN CAL INTO THE SRN OREG. HIGH PRES

1034 MB W OF THE WATERS NR 42N145W HAS ITS RIDGE OVER MOST OF THE

REGION. THE PRES GRADIENT IS TIGHT OVER THE NRN CAL AND SRN OREG

WATERS BUT QUITE SLACK ELSEWHERE.



MOST OF THE ENERGY IS JUST E OF AN UPPERLEVEL HIGH PRES CENTERED

NR 40N140W. THERE IS ANOTHER UPPERLEVEL HIGH PRES INLAND OVER THE

S-WRN STATES. THE TWO AREAS OF HIGH PRES HAVE CAUSED A SLOW DOWN

ON THE MOVEMENT OF OTHER SYNOP FEATURES. MOST OF THE ENERGY WILL

CONTINUE TO LINGER AROUND THE CNTRAL WATERS AND THAT WILL MAINTAIN

THE CURRENT SYNOPTIC FEATURES PATTERN. AS THE ENERGY SLOWLY SHIFTS

E OF THE WATERS IN THE EXTENDED PERIOD...AN UPPERLEVEL HIGH WILL

MOVE E INTO THE WATERS AND THAT WILL FORCE A RELAXED PRES GRADIENT

AND ALLOW WINDS TO DIMINISH BELOW GALE WARNING THRESHOLD.

 

THE GLOBAL MODELS HAVE INITIALIZED VERY WELL AND THEY ARE IN

GENERALLY A GOOD AGREEMENT ON THE FEW SYNOP FEATURES THAT ARE

CONTROLLING THE WX OVER THE REGION. WILL UPDATE THE FORECAST

WITHOUT MAJOR CHNAGES TO THE PREVIOUS FORECAST AND WILL STAY WITH

JUST GFS. IN THE SHORT TERM HGH PRES WILL REMAIN TO THE W AS

INLAND TROF PERSITS OVER CAL. THE WINDS WILL REMAIN ELEVATED IN

THE SHORT TERM BUT WILL DIMINISH TO BELOW GALE FORCE IN THE

EXTENDED PERIOD.



.SEAS...THE SEAS PEAK AT 12 FT OVER THE CENTRAL REGION AND THEY

RANGE BETWEEN 4 AND 7 OVER THE FAR SRN AND NRN WATERS. THE JASON

SWATHS AT 1712Z AND 1915Z MISSED THE CENTRAL WATERS BUT INDC SEAS

TO 5 FT OVER THE FAR NRN AND FAR SRN WATERS. THE NWW3 MULTI GRID

WAVE MODEL FITS FAIRLY WELL WITH THE OBSERVED SEAS PATTERN AND HAS

BEEN VERY CONSSISTENT. WILL STAY WITH ENP. IN THE SHORT TERM THE

SEAS WILL REMAIN LARGE OVER THE CENTRAL WATERS WITH PEAKS TO 15 FT

WHILE SEAS WILL JUST SUBSIDE IN THE EXTENDED PERIOD TO PEAKS AT 13

FT.



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



.WARNINGS...PRELIMINARY.



.PZ5 WASHINGTON/OREGON WATERS...

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

     GALE TONIGHT INTO SAT NIGHT. 

.PZZ900...OUTER WATERS FROM CAPE FLATTERY TO CAPE SHOALWATER...

     GALE TONIGHT.

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

     GALE TONIGHT INTO SUN. 



.PZ6 CALIFORNIA WATERS...

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

     GALE TONIGHT INTO SUN. 

     GALE POSSIBLE SUN NIGHT.

     GALE POSSIBLE TUE NIGHT INTO WED NIGHT. 

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

     GALE SAT.



$$



.FORECASTER BANCROFT/MUSONDA. OCEAN PREDICTION CENTER.

