

132 

AGPN40 KWNM 040223

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

723 PM PDT SAT SEP 3 2016



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

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



UPDATE...18Z NCEP SFC ANALYSIS SHOWS AN INLAND LOW PRES TROF OVER

CALIFORNIA...WITH A HI PRES RIDGE BUILDING E AND NE TOWARDS THE

WEST COAST OF CONUS. LATEST AVAILABLE ASCAT HI-RES PASSES FROM

EARLIER THIS EVENING INDICATE N TO NW WINDS OF 20 TO 25 KT IN THE

SRN OREGON/NRN CALIFORNIA COASTAL WTRS...AND ALSO IN THE ADJACENT

NRN PZ6 WTRS.



MAIN WEATHER FEATURES...A COUPLE OF RELATIVELY WEAK LOWS ARE

EXPECTED TO SLIDE OVER THE TOP OF THE EPAC RIDGE AND PASS SE

ACROSS THE PZ5 AREA LATE MON INTO TUE...THEN AGAIN WED INTO THU.

OTHERWISE THE CALIFORNIA TROF AND THE EPAC RIDGE WILL PREVAIL THRU

THE FCST PERIOD AND PRODUCE ROBUST N TO NW FLOW OVER THE NRN AND

CENTRAL CALIFORNIA OFSHR/COASTAL WTRS.



MODELS...THE MED RNG MDLS ARE IN VERY GOOD OVERALL AGREEMENT

ACROSS THE OFSHR/COASTL WTRS THRU THE FCST PERIOD...EXCEPT THE

CANADIAN GEM LOOKS OVERDONE WITH THE N TO NW FLOW FOR TUE NITE

INTO THU NITE. AM GOING TO USE A REPRESENTATIVE 50/50 BLEND OF THE

GFS 30M/10M SOLNS...WHICH KEEPS THE WINDS SUB-GALE DURING THE FCST

PERIOD BUT ALSO ALLOWS 30 KT N TO NW WINDS IN THE OFSHR/COASTAL

WTRS. AM NOT PLANNING TO MAKE ANY SIGNIF CHANGES TO THE CURRENT

FCST TREND.



SEAS...THE ENP WAVEWATCH III MDL AND ECMWF BOTH LOOK REASONABLE

WITH THE SEA HTS THRU THU NITE...AND ARE ALSO IN VERY GOOD OVERALL

AGREEMNT. WILL CONTINUE TO USE THE ENP WAVEWATCH III MDL FOR THE

WAVE HT GRIDS THRU THE ENTIRE FCST PERIOD.



EXTRATROPICAL STORM SURGE GUIDANCE...N/A.



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

PREVIOUS DISCUSSION...



THRU THU NIGHT THE PATTERN OVER THE ERN PAC IS EXPECTED TO CHANGE

LITTLE AS A SERIES OF MID/UPR SHRTWV TROFS MOV OVER A BROAD UPR

RIDGE W OF THE WATERS AND PASS SE OVER OR JUST N OF THE PZ5

WATERS AND MOV INLAND OVR PAC NW. THE FIRST OF THESE APPEARS IN

GOES W/V IMAGERY OVR WASHINGTON WATERS WITH WK SFC REFLECTIONS IN

FORM OF SFC TROF OVR VANCOUVER ISL AND A WK LOW NR 42N134W. THE

EFFECT OF THESE IS TO KEEP THE ERN PAC HIGH WELL W OF WATERS AND

WINDS STAYING BELOW GALE FORCE IN OFSHR WTRS. WINDS COULD APPROACH

GALE FORCE OFF NRN CA ESPCLY LATE AFTERNOONS AND EVENINGS INTO TUE

NIGHT AS THE PERSISTENT THERMAL TROF OVR CA STRENGTHENS

DIURNALLY. FOR TUE NIGHT INTO WED NIGHT MDLS SHOW THE EPAC HIGH

PRES SHIFTING E AND BUILDING A RIDGE INTO PZ5 WTRS WITH SOME

ENHANCEMENT OF THE GRADIENT BETWEEN THE CSTL TROF AND RIDGE. WIND

CONDS APPR TO MAXIMIZE OFF CENTRAL AND NRN CA ARND THAT TIME. FOR

THE NEW FCST GRIDS POPULATED THE FIRST PERIOD WITH THE 12Z GFS 30M

WINDS AS THESE APPEAR REPRESENTATIVE WHEN COMPARED TO 17Z-19Z HIGH

RES ASCAT-B PASSES. FOR THE REMAINDER OF THE FCST USED A

COMPROMISE 50/50 BLEND OF 12Z GFS 10M AND 30M WINDS WHILE LIMITING

GRID VALUES TO 32 KT OR LESS DURING PERIOD OF STRONGEST WINDS. THE

12Z CMC GEM HAS STRONGEST CONDS AND SHOWS GALES EXTENDING INTO

OFSHR WTRS WED NIGHT THRU THU NIGHT AND EVEN BEYOND WHEREAS 12Z

ECMWF/UKMET SHOW NO GALES AND 10M WINDS UP TO 30 KT. HENCE THE NEW

FCST WILL CONTINUE TO CARRY NO HEADLINES.



THE 12Z ENP NWW3 LOOKS REASONABLE WITH THE SEAS AND WILL BE

FOLLOWED FAIRLY CLOSELY THRU THU NIGHT...WITH 12Z ECMWF WAM CLOSE

WI A FOOT.



EXTRATROPICAL STORM SURGE GUIDANCE...N/A.



.WARNINGS...PRELIMINARY.



.PZ5 WASHINGTON/OREGON WATERS...

     NONE.



.PZ6 CALIFORNIA WATERS...

     NONE.



$$



.FORECASTER SCOVIL/BANCROFT. OCEAN PREDICTION CENTER.

