

219 

AGPN40 KWNM 050338

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

838 PM 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 1037 MB HIGH PRES REMAINS CENTERED W OF THE PZ5 OFFSHORE

WTRS NEAR 45N148W THIS EVENING...WITH AN INLAND TROF EXTENDING

THRU CENTRAL/NRN CA AND TOWARD SW OREGON PER THE 00Z NCEP SFC

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

WITH THE RESULTANT ENHANCED PRES GRADIENT ESPCLY OVER E PORTIONS

NEAR THE COAST. NO NEW SCATTEROMETER PASSES ARE AVBL ALTHOUGH 00Z

RAPIDSCAT DATA IS BGNG TO COME IN AND SHOWS LIGHT WINDS OFF NRN

BAJA PENINSULA WHICH IS NO SURPRISE GIVEN ITS LOCATION ADJ TO

INVERTED INLAND TROF. THE 00Z NAM/18Z GFS BOTH SUGGEST THE

STRONGEST WINDS ARE NOW CONFINED TO INNER ZONES AND ADJ CSTL AREAS

FM PT ST GEORGE AREA NWD OVR INNER OREGON WTRS AND THERE ALSO

APPRS TO BE WIND MAX OFF VANCOUVER ISL AND EXTENDING INTO NE WA

WTRS...WITH ENHANCED GRADIENT BETWEEN HIGH TO W AND A TROF WHICH

HAS EXTENDED N INTO BC...BUT EVEN 30M WINDS ONLY SHOW 30 KT.

THEREFORE WILL CONTINUE TO CARRY NO GALE WARNINGS IN EVENING

UPDATE...ALTHOUGH 25-30 KT NLY WINDS WILL CONTINUE ACROSS THESE

AREAS THRU TONIGHT. OTHERWISE NO FCST CHANGES WERE NECESSARY

ATTM.

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

PREVIOUS DISCUSSION...



A TYPICAL SUMMER PATTERN PREVAILS ACROSS THE E PAC THIS AFTN. THE

18Z NCEP SFC ANALYSIS SHOWS A 1038 MB HIGH NEAR 45N148W WITH A

1009 MB THERMAL LOW ANALYZED IN NRN CA. BETWEEN THESE TWO SFC

FEATURES...ENHANCED NLY FLOW PERSISTS OVER THE PZ5/NRN PZ6 WTRS.

AN ASCAT PASS AROUND 1745Z CONFIRMED A SWATH OF 20-30 KT WINDS

ACROSS THE FAR E PORTION OF THE SRN PZ5/NRN PZ6 WTRS. NO GALES

WERE DETECTED...EVEN OVER THE COASTAL WTRS...AS THE OFFSHORE HIGH

SLOWLY BEGINS TO WEAKEN THIS AFTN.



THE PRES GRADIENT ALONG THE W COAST WILL GRADUALLY RELAX OVER THE

NEXT COUPLE DAYS AS AN UPR LOW NEAR THE COAST OF BRITISH COLUMBIA

MOVES S TO VANCOUVER ISLAND ON FRI AND CONTINUES DRIFTING S THRU

SUN. THE 12Z GLOBAL MODELS ALL SHOW WEAKENING HIGH PRES OFFSHORE

AND DIMINISHED WIND SPEEDS THRU THE WEEKEND...GENERALLY BECOMING

15-20 KT OVER THE PZ6 AND SRN PZ5 WTRS BY SUN. THIS UPR LOW WILL

MOVE INLAND ACROSS WA SUN NIGHT INTO MON...ALLOWING THE OFFSHORE

RIDGE TO RESTRENGTHEN THRU THE END OF THE FCST PERIOD. BY 12Z

TUE...THE GFS/ECMWF SUGGEST GALE CONDITIONS COULD POSSIBLY DEVELOP

ONCE AGAIN OFF THE NRN CA COAST. WILL CAP WINDS FOR TUE AT 30 KT

OVER THE NRN PZ6 WTRS ATTM GIVEN THE INHERENT UNCERTAINTY ON DAY

5...BUT THIS LOOKS TO BE THE NEXT FCST CHALLENGE.



WITH THE GFS/ECMWF/UKMET ALL IN VERY GOOD AGREEMENT THRU TUE...SAW

NO REASON TO DEVIATE FAR FROM THE 12Z GFS 10M WINDS...WHICH SEEM

TO HAVE INITIALIZED WELL BASED ON OBS AND RECENT ASCAT DATA.



.SEAS...USED THE 12Z NWW3 GRIDS THRU TUE WITH MINOR NEAR TERM

ADJUSTMENTS. BOOSTED SEAS A BIT THRU TONIGHT TO MAINTAIN 12 FT

SEAS IN THE NRN PZ6 ZONES...WHICH MATCHES UP WELL WITH OUR

ADJACENT WFOS AND AN EARLIER ALTIMETER PASS.



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



.WARNINGS...PRELIMINARY.



.PZ5 WASHINGTON/OREGON WATERS...

     NONE.



.PZ6 CALIFORNIA WATERS...

     NONE.



$$



.FORECASTER BANCROFT/REINHART. OCEAN PREDICTION CENTER.

