

031 

AGPN40 KWNM 020331

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

831 PM PDT MON AUG 1 2016



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

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



00Z SFC ANALYSIS SHOWS A DISSIPATING CDFNT ENTERING THE NRN CA

WTRS AND SRN OREGON CSTL WTRS WITH A SFC TROF FOLLOWING BHEHIND IT

AND INTERING THE WA WTRS FM THE NW. STG HIGH PRES PERISTS NR

45N148W. BASED ON 18Z ASCAT-B PASS SHOWING AN AREA OF 30 KT IN PT

ST GEORGE AREA IN CSTL WTRS AND DIURNAL TREND TWD STRENGHTHENING

OF GRADIENT BETWEEN THERMAL TROF AND RDG IN LATE AFTERNOON AND

EVENING...LEFT THE POSSIBILITY OF GALES IN PLACE EARLY IN THE

FIRST PERIOD BUT MAINLY IN CSTL WTRS WITH A BLEND OF 12Z GFS 10M

AND 30M WINDS WEIGHTED 67 PCT IN FAVOR OF LOWER 10M WINDS LOOKING

REPRESENTATIVE.



LATEST MDLS CONTINUE TO SHOW A MID/UPR LVL LOW MOVG SE AND ONSHR

OVR WA EARLY TUE WITH THE AFOREMENTIONED TROF ITS SFC REFLECTION.

THIS WILL ALLOW THE EPAC UPR RDG TO BUILD E TWD THE WTRS ALG WITH

THE SFC HIGH...BUT THE APCH OF ANOTHER UPR LVL SYSTEM FROM THE NW

WED NIGHT INTO THU NIGHT WILL NOT ALLOW SFC HIGH TO BUILD TOO

STRONGLY. LATEST 18Z GFS HAS TRENDED SLGTLY WEAKER WITH ASCD SFC

GRADIENTS TUE NIGHT INTO THU NIGHT BUT STILL MAY SUPPORT THE

EXPANSION OF MRGL GALES INTO PORTION OF INNER NRN CA ZONE WED INTO

THU NIGHT. TO MAINTAIN CONTINUITY CONTINUED TO FAVOR A BLEND OF

12Z GFS GUIDANCE WEIGHTED 67 PCT TOWARD THE HIGHER 30M OR FIRST

SIGMA LVL WINDS. HAVE ONLY MDT CONFDC IN THESE GALES FOR THE OFSHR

WTRS. LEFT THE CURRENT GRIDS UNCHANGED AS THEY REVERT BACK TO A

HIGHER CONTRIBUTION OF GFS 10M WINDS FOR FRI AND BEYOND AS THE

SECOND UPR LOW DROPS SE TO WRN WA AND WKNS THE GRADIENTS TO SPRT

MOSTLY 25 KT OR LESS BY SAT.



THE 18Z ENP WW3 AS WELL AS PREVIOUS RUN ARE INITIALIZED UP TO 2 FT

LOW WITH HIGHEST SEAS OFF NRN AND CENTRAL CA WITH 12Z ECMWF WAM

CLOSER TO 00Z SEA STATE ANALYSIS. LEFT CURRENT SEA STATE GRIDS IN

PLACE BASED ON 12Z WW3 AS SEAS ARE BOOSTED BY 10 PCT FOR HEIGHTS 9

FT OR GREATER THRU FRI.

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

PREVIOUS DISCUSSION...



AT 18Z A WEAK SURFACE LOW WAS LOCATED JUST OFF VANCOUVER ISLAND 

WITH A COLD FRONT EXTENDING S AND SW FROM LOW ACROSS THE PZ5 

WATERS. LATEST MODELS ARE IN GOOD AGREEMENT THAT THE COLD FRONT 

SHOULD DIMINISH AS IT MOVES THROUGH THE NRN PZ6 WATERS 

TONIGHT... WITH THE ASSOCIATED MID/UPPER LEVEL LOW MOVING 

ONSHORE ACROSS WA  EARLY TUE. AN 18Z METOP-A ASCAT OVERPASS 

INDICATED HIGHEST WINDS TO 30 KT ACROSS COASTAL ZONES FROM CAPE 

BLANCO TO PT ST GEORGE. THERE WERE ALSO SOME 30 KT RETURNS ABOUT 

60 TO 80 NM WSW OF CAPE MENDOCINO. THE 12Z GFS WINDS LOOK WELL 

INITIALIZED ACROSS THE COASTAL ZONES BUT MAY BE 5 KT OR SO 

ACROSS INNER ANZ820 WATERS.  



THE 12Z MODELS ARE IN GOOD AGREEMENT THAT HIGH PRES CENTERED 

NEAR 45N148W AT 18Z WILL DRIFT E WHILE STRENGTHENING OVER THE 

NEXT 24 TO 36 HOURS AND THEN PERSIST INTO THE WEEKEND. OVER THE 

PAST FEW RUNS THE MODELS HAVE GENERALLY TRENDED WEAKER WITH THE 

N WINDS FROM CAPE BLANCO TO PT ARENA THIS WEEK. THE 12Z GFS NO 

LONGER SHOWS ANY GALE FORCE WINDS EXTENDING BEYOND 60 NM INTO 

OFFSHORE WATERS. FOR CONTINUITY HAVE DECIDED NOT TO DROP THE 

GALES BUT DID ADJUST THE PREVIOUS BLEND OF THE GFS 10M AND FIRST

SIGMA LAYER WINDS WITH HIGHER CONTRIBUTION FROM THE LOWER 10M

WINDS. ONLY HAVE MODERATE CONFIDENCE WITH THESE GALES BUT WILL

AWAIT SUBSEQUENT MODEL RUNS BEFORE DROPPING THEM ENTIRELY.



THE 12Z WAVEWATCH III AND 12Z ECMWF WAM ARE WELL INTIALIZED WITH 

WAVE HEIGHTS ACROSS THE E PACIFIC THIS AFTERNOON. OPC WAVE 

HEIGHT GRIDS ARE LARGELY BASED ON THE 12Z WW3. HOWEVER GRIDS 

WERE ADJUSTED UPWARD BY ABOUT 10 PERCENT ACROSS AREAS WITH WINDS 

GREATER THAN 25 KT AND/OR SEAS GREATER THAN 9 FT OFF NRN 

CALIFORNIA TUE THROUGH FRI. 



.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.

     GALE POSSIBLE WED NIGHT.

     GALE POSSIBLE THU NIGHT.



$$



.FORECASTER BANCROFT/CLARK. OCEAN PREDICTION CENTER.

