

041 

AGPN40 KWNM 041453

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

753 AM PDT THU AUG 4 2016



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

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



STNRY 1039 MB HIGH PRES IS CENTERED W OF THE OFFSHORE WTRS NEAR

45N149W THIS MORNING...WITH AN INLAND TROF EXTENDING THRU

CENTRAL/NRN CA AND INTO OREGON PER THE 12Z NCEP SFC ANALYSIS.

STRONG NLY FLOW PERSISTS OVER THE SRN OR/NRN CA WTRS WITH THE

RESULTANT ENHANCED PRES GRADIENT ALONG THE COAST. UNFORTUNATELY

THERE WERE NO NEW SCATTEROMETER PASSES TO HELP ASSESS THE AREA OF

SUSPECTED GALES ROUGHLY FROM CAPE BLANCO TO CAPE MENDOCINO. THE

12Z NAM/06Z GFS BOTH SUGGEST THE STRONGEST WINDS ARE NOW CONFINED

TO THE COASTAL WTRS...WITH EVEN THE 30M GFS WINDS KEEPING GALES E

OF OUR OFFSHORE ZONES. THEREFORE WILL DROP THE GALE WARNING FOR

PZZ815/820 WITH THIS MORNING UPDATE...ALTHOUGH 25-30 KT NLY WINDS

WILL CONTINUE ACROSS THESE ZONES THRU TONIGHT. OTHERWISE NO FCST

CHANGES WERE NECESSARY ATTM.



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PREVIOUS DISCUSSION...



PERSISTENT PATTERN CONTS OVER THE NE PAC WITH STNRY STRONG HIGH

PRES NEAR 45N 148W WITH RIDGING INTO NRN WTRS. IN COMBINATION WITH

THERMAL TROF FM CENTRAL CA INTO SW OREGON THIS HAS BEEN PRODUCING

NLY GALES BETWEEN CAPE BLANCO AND CAPE MENDOCINO IN CSTL WTRS.

0435Z ASCAT-A PASS RETURNED MORE WDSPRD SOLID 30 KT EXTENDING

FARTHER N AND W OVER OREGON OFSHR WTRS AND 20 TO 25 KT ELSW N OF

PT CONCEPTION. A COMAPRISON OF LATEST SHIP OBS AND ASCAT PASSES

INDICATE 00Z GFS 30M WINDS LOOKS REPRESENTATIVE TO START

FCST...AND WITH THE EXPANDED 30 KT APPEARING IN ASCT IS IS PSBL

GALES MAY EXTEND INTO ZONE PZZ820 AND EVEN FAR SE PZZ815.

THEREFORE WILL POPULATE WITH 00Z GFS 30M WINDS FOR TODAY INTO

TONIGHT...AS LATER TODAY INTO TONIGHT THE APCH OF AN UPR LOW NOW

OVR SE AK LOWERS PRESSURES AND EXPANDS THE INLAND TROF NWD INTO BC

WITH 00Z GFS AND TO LESSER EXTENT 00Z CMC GEM DVLP A PINCHING OF

GRADIENT OFF VANCOUVER ISL BTWN RDG TO W AND EXPANDED TROF. USE OF

30M WINDS RESULTS IN SML AREA OF GALES JUST N OF WA WTRS LATER

TODAY OR EARLY TONIGHT WHICH VANCOUVER EC OFFICE IS CARRYING.



LATEST 00Z MDLS AGREE IN WKNG THE GRADIENTS OFSHR CA AND SRN

OREGON TODAY AND TONIGHT AS THE UPR LOW DROPS SSE TO VANCOUVER ISL

LOWERING H5 HEIGHTS OVR OFSHR AREAS AND WKNG THE SFC RDG OVR THE

WTRS. THIS TREND CONTINUES FRI AS THE UPR LOW DROPS SSE TO WA

COAST OVER WEEKEND AND WEAKEN THE OFSHR RDG FURTHER...RELAXING THE

GRADIENT MORE. ON MON AND MON NIGHT THE UPR LOW MOVS INLAND

ALOWING THE EPAC RDG TO BUILD IN FM THE W. WILL HAVE TO WATCH FOR

THE POSSIBILITY OF GALES REDVLPG OFF NRN CA AT LEAST IN THE CSTL

WTRS WITH GFS THE STRONGEST. FOR THE NEW FCST POPULATED THE WIND

GRIDS WITH A 1/3 00Z GFS 30M AND 2/3 GFS 10M WIND BLEND FOR LATER

THU NIGHT THRU SAT NIGHT AND THEN SHIFTED TWD 00Z GFS 10M WINDS

FOR SUN THRU MON NIGHT WHICH IS ACTUALLY SIMILAR TO ECMWF...AND

DVLPS GALE FORCE BL WINDS IN NRN CA CSTL WTRS MON NIGHT. WITH 00Z

UKMET AND CMC GEM WEAKER...HAVE CHOSEN NOT TO BOOST THESE WINDS AT

THIS TIME.



.SEAS...THE 00Z ECMWF WAM IS SLIGHTLY PREFERRED INITIALLY OVR 00Z

NWW3 TODAY WITH A 10 PCT WAVE HGT BOOST IN THE NEAR TERM TO

ACCOUNT FOR THE MODELS RUNNING SLIGHTLY LOW WITH GALES IN THE

FCST. OTRW FM LATER TODAY AND AFTERWARDS POPULATED WITH THE 00Z

ENP NWW3 WHICH IS SIMILAR TO 00Z ECMWF WAM.



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





.WARNINGS...PRELIMINARY.



.PZ5 WASHINGTON/OREGON WATERS...

     NONE.



.PZ6 CALIFORNIA WATERS...

     NONE.



$$



.FORECASTER REINHART/BANCROFT. OCEAN PREDICTION CENTER.

