Marine Interpretation Message
Issued by NWS

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AGPN40 KWNM 271453
MIMPAC

MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
753 AM PDT WED JUL 27 2016

.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH PACIFIC N OF 30N AND E OF 150W.

THE 12Z OPC SFC ANALYSIS INDICATES A TIGHT PRES GRADIENT OVER THE
NRN CA/SRN OR WATERS THIS MORNING BETWEEN SFC HIGH PRES W OF THE
WATERS AND A THERMAL LOW OVER NRN CA. BASED ON THE 12Z OBS AND SEA
STATE ANALYSIS...HAVE EXPANDED THE AREA OF 12 FT SEAS AND NUDGED
MAX SEAS UP TO 13 FT OVER THE NRN CA WATERS AS BOTH WAVE MODELS
CONTINUE TO RUN A BIT LOW THIS MORNING. OTHERWISE...NO
SIGNIFICANT CHANGES WERE NECESSARY WITH THIS FCST UPDATE. GALE
CONDITIONS WILL RESUME OFF THE NRN CA COAST THIS AFTN AS INLAND
DAYTIME HEATING STRENGTHENS THE PRES GRADIENT OFFSHORE.

-----------------------------------------------------------------
PREVIOUS DISCUSSION...

THE LTST GOES WV IMGRY INDC AN UPR RDG OVER THE COAST...AND THE
LTST NCEP SFC ANALYS INDC STG HIGH PRES JUST W OF THE NRN CAL OFSHR
WTRS. THE ANALYS ALSO INDC A STG HEAT LOW OVR NRN CAL WITH A HEAT
TROF EXTENDING TO THE S IN THE CENTRAL CAL VALLEY...BEING FUELED
EARLIER BY TRIPLE DIGIT HEAT OVER MOST LOWER ELEVATIONS IN THE CAL
INTERIOR. THE RESULTANT STG PRES GRAD BTWN THE HEAT TROF AND THE
STG HIGH PRES TO THE W HAS INCRSD THE WINDS...HIGHEST OFF THE NRN
CAL COAST. CRNT SFC RPRTS INDC ONLY UP TO 25 KT...THO NONE ARE IN
THE STGT PART OF THE PRES GRAD...BUT THE 05Z ASCAT WIND RETRIEVALS
INDC GALES JUST W OF PT ST GEORGE...IN THE COASTAL WATERS. THE 00Z
GFS 10M WINDS ARE INIT A LTL LOW WHEN COMPARED WITH THE DATA...AND
THE 30M WINDS ARE INIT A LTL STG. THE 00Z GEM WINDS ARE ALSO INIT
A LTL TOO STG...AND INDC 40 KT IN THE COASTAL WATERS. THE 00Z
ECMWF/UKMET ARE INIT LOW. THE PREV FCST WENT WITH A BLEND OF THE
GFS 10M AND 30M WINDS...WHICH SEEMS TO PRODUCE THE MOST
REPRESENTATIVE WINDS. AS A RESULT...PLANNING ON USING THIS SAME
BLEND TO START OFF WITH...AND WL EXPAND GALES OVR THE OFSHR WTRS
LATER TDA AS THE INTERIOR HEATS UP AGAIN.

OTRW...THE 00Z GFS AGREES SOMEWHAT WELL WITH THE REST OF THE 00Z
THRUT THE FCST PD...AND ALL SOLNS INDC THE RDG WL SLOWLY
STRENGTHEN OVR THE NEXT FEW DAYS AND CONTINUE INTERACTING WITH THE
TROF. THE 00Z MDLS MAINTAIN GALES OFF THE NRN CAL COAST...SO
PLANNING ON STAYING WITH THE GFS SOLN AS IT INDC GALES IN THE
NRN PZ5 OFSHR WTRS INTO SAT...AS IT HAS BEEN CONSISTENT WITH THIS
SCENARIO AND IS IN GOOD AGRMT WITH THE REST OF THE 00Z GUID.

THE BIGGEST FCST PROBLEM IS A SECONDARY AREA OF GALES THAT THE GFS
HAS BEEN CONSISTENLY SHOWING OVER THE NE WAS WATERS. THE MDLS ALL
INDC A SECOND TROF WL DEVELOP OVR THE WAS COAST AND EXTEND N INTO
BC...WHILE INTERACTING WITH HIGH PRES SW OF THE AREA. THE MDLS
ALSO INDC A WK COLD SURGE BEHIND A WK SFC BNDRY WL MOV INTO THE
FAR E PAC...AND LOW STATIC STABILITY TO ALLOW GREATER MIXING OF
STRONGER WINDS ALOFT TO THE SFC. THE 00Z GFS/NAM/ECMWF 925 MB
WINDS ALL INDC GALES FRI NGT INTO SAT...UP TO 45 KT. SOME OF THESE
HIGHER WINDS SHUD MIX DOWN...AS NOTED EARLIER. IN ADDITION...N
FLOW OFF THE HIGHER TERRAIN IN VANCOUVER ISLE SHUD ALSO PROVIDE
SOME ACCELERATION TO THE SFC WINDS...IN THE FORM OF LL CONFLUENCE.
THE PREV FCST HELD OFF ON THE GALES FOR FRI NGT INTO SAT NGT...AS
CONFDC WAS LOWER. HOWEVER...CONFDC IS NOW MDT WITH THE GUD MDL
AGRMT BTWN 00Z SOLNS...AND NOW SEEMS LIKELY WITH THE LOWER STATIC
STABILIY/GALES ALOFT/LL CONFLUENCE. AS A RESULT...PLANNING ON
ADDING GALES TO THE NE WAS WTRS IN THE NEXT FCST. OTRW WL STAY NR
THE 00Z GFS FOR THE REMAINDER OF THE FCST.

SEAS...THE 00Z WAVEWATCH-III AND ECMWF WAM ARE INIT A FT OR TWO
LOW INVOF THE GALES OFF THE NRN CAL COAST...SO WL NEED TO BOOST
SEAS INITIALLY. OTRW...THE 00Z MDLS ARE IN VERY GOOD AGREEMENT
THROUGHOUT THE FCST PERIOD. AS A RESULT...PLANNING ON FAVORING THE
00Z NWW3...WHICH IS SUPPORTED BY THE 00Z ECMWF WAM...AND BEST
REFLECTS PREFERRED WX MDL TRENDS.

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


.WARNINGS...PRELIMINARY.

.PZ5 WASHINGTON/OREGON WATERS...
.PZZ800...INNER WATERS FROM CAPE FLATTERY TO CAPE SHOALWATER...
     GALE POSSIBLE FRI NIGHT INTO SAT NIGHT.
.PZZ815...INNER WATERS FROM FLORENCE OR TO POINT ST. GEORGE...
     GALE THU NIGHT.
     GALE POSSIBLE FRI INTO SAT NIGHT.

.PZ6 CALIFORNIA WATERS...
.PZZ820...INNER WATERS FROM POINT ST. GEORGE TO POINT ARENA...
     GALE TODAY INTO THU NIGHT.
     GALE POSSIBLE FRI INTO SUN NIGHT.
.PZZ920...OUTER WATERS FROM POINT ST. GEORGE TO POINT ARENA...
     GALE POSSIBLE FRI NIGHT INTO SAT NIGHT.

$$

.FORECASTER REINHART/KELLS. OCEAN PREDICTION CENTER.


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