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000
AGPN40 KWNM 260330
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
830 PM PDT Sun Jun 25 2017

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

The grids and the previous text forecast look good and therefore
I dont plan on making any changes. The overall pattern across the
eastern pacific is expected to remain quiet with mainly light
winds, until later in the week when a predominate northernly flow
persists across the area.

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

The latest satellite imagery and lightning density data indicates
a few thunderstorms occurring over southern Oregon offshore
waters, and also just south of the southernmost southern
California offshore waters early this afternoon. The
thunderstorm activity appears to mostly be associated with an
upper level low pressure area centered west of the northern
California waters at this time. The upper level low is expected
to weaken and drift northeast into tomorrow, with any
thunderstorm activity also likly diminishing by tomorrow as
well. We will add thunderstorms to a few offshore zones,
especially southern Oregon and far southeastern California
waters for tonight, as a result.

Otherwise, no significant changes to the previous and ongoing
OPC forecast appears necessary for the afternoon package. The
12Z models are all in very good agreement over the region for
the next few days. We will stay close to the 12Z GFS 10 meter
winds throughout the forecast period. The threat for gales will
increase just west of Vancouver Island tonight and tomorrow, and
continue into Tuesday and Tuesday night, with these gales likely
remaining north of the offshore waters, in coordination with
Environment Canada. There will be another chance of gales
especially over the coastal waters of far northern Calfornia and
far southern Oregon by later Wednesday, with chances remaining
over these waters Thursday before potentially spreading
southward along most of the California coast by Friday. At this
time, the threat is too low to add any gales to the offshore
waters, but this threat will continue to be monitored over the
next few days. Otherwise, we expect a weakening cold front to
reach far western PZ5 waters Thursday night or Friday, as high
pressure builds to the west of the California or PZ6 waters.
As the high builds to the west of the offshore waters the chance
of gales will potentially increase over especially the northern
California offshore waters next weekend, currently beyond day 5
of latest OPC offshore forecast.

Seas...Both the 12Z ENP Wavewatch III and 12Z ECMWF WAM models
appear to have intialized within a foot or two of the
obervations noted over the offshore waters this afternoon. There
are only minor differences in the model output over the next 5
days across most of the eastern North Pacific. We prefer to use
a 50/50 blend of these two models in an attempt to limit
forecast error over the waters during the next few days.

Extratropical Storm Surge Guidance: n/a.


.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
     None.

$$

.Forecaster Shaw/Mills. Ocean Prediction Center.



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