Marine Interpretation Message
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000
AGPN40 KWNM 170821
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
121 AM PDT Tue Oct 17 2017

.FORECAST DISCUSSION...Major features/winds/seas/significant
.weather for the North Pacific N of 30N and E of 150W.

A series of strong frontal systems will impact conditions over
mainly Washington and Oregon offshore waters into the weekend
with periods of gale force winds and building seas. Forecast
confidence is near average with the 00Z models in pretty good
agreement over the region during the next few days.

Over the short term, the first cold front to impact the waters is
moving SE over Washington offshore waters early this morning. Any
gales associated with the front will likely occur early this
morning prior to forecast issuance, so we will not start the
offshore forecast with any gales unless later data shows the need
to add gales initially to the forecast. This front will move SE
and weaken today, then stall over southern Oregon waters tonight
as the next strong front approaches from the W. This front will
cross Washington and Oregon waters later tonight and Wed with
gales likely over many portions of the offshore waters. The front
will move into northern California waters Wed night, with the
front weakening at that time so we will keep winds below gale
force. A secondary front or trough will swing eastward over
Washington and Oregon waters during Thu providing a threat for
gales over mainly NW Washington offshore waters. Overall, the 00Z
models are remaining quite consistent and in good agreement over
the region today through Thu. We will rely on the 00Z GFS
guidance over the short term with little change from the past few
OPC forecasts.

Over the longer term, a temporary lull in the gales is expected
over the region Thu night into Fri as a weak high pressure ridge
develops and moves E over the region. The next frontal system
will approach Washington, Oregon and NW northern California
offshore waters by later Fri. There will be an increasing threat
for widespread gales over most of the Washington and Oregon
offshore waters Fri night into Sat and Sat night as the next
strong front crosses the area. For the longer term part of the
forecast we will trend the grids and forecast more toward the 00Z
ECMWF solution as it has remained the most consistent over the
past few days.

Weather...We will continue to show a chance for scattered
showers and a few thunderstorms over parts of the southern
California offshore zones today into tonight as the latest
lightning data continues to indicate mainly west of zone PZZ940
early this morning, with the latest RAP and 00Z GFS indicating
the activity will spread east and northeast today into tonight
before weakening or ending. Further north, widespread rain and
shower activity will occur near each front that crosses
Washington and Oregon waters during the next few days.

.SEAS...The 00Z ENP Wavewatch may be running a foot or so too
high over the region early this morning, with the 00Z ECMWF WAM
a tad on the low side. For the early morning package we will use
a 50/50 blend of these two wave models in an attempt to limit
forecast errors for today through Thu night. For Fri through Sat
night, as we use the ECMWF for winds, we will use the WAM for
sea heights during this time frame.

.EXTRATROPICAL STORM SURGE GUIDANCE...n/a.

.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
.PZZ800...Inner Waters from Cape Flattery to Cape Shoalwater...
     Gale tonight into Wednesday.
     Gale Possible Saturday.
.PZZ900...Outer Waters from Cape Flattery to Cape Shoalwater...
     Gale tonight into Wednesday night.
     Gale Possible Thursday.
     Gale Possible Friday night into Saturday.
.PZZ805...Inner Waters from Cape Shoalwater to Cape Lookout...
     Gale Wednesday into Wednesday night.
     Gale Possible Saturday into Saturday night.
.PZZ905...Outer Waters from Cape Shoalwater to Cape Lookout...
     Gale tonight into Wednesday night.
     Gale Possible Friday night into Saturday.
.PZZ810...Inner Waters from Cape Lookout to Florence OR...
     Gale Wednesday night.
     Gale Possible Friday night into Saturday night.
.PZZ910...Outer Waters from Cape Lookout to Florence OR...
     Gale Wednesday into Wednesday night.
     Gale Possible Friday night into Saturday.
.PZZ815...Inner Waters from Florence OR to Point St. George...
     Gale Possible Friday night into Saturday.
.PZZ915...Outer Waters from Florence OR to Point St. George...
     Gale Wednesday into Wednesday night.
     Gale Possible Friday night.

.PZ6 California Waters...
     None.

$$

.Forecaster Mills. Ocean Prediction Center.



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