Marine Interpretation Message
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000
AGPN40 KWNM 251431
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
731 AM PDT Mon Sep 25 2017

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

A weak cold front extends across the far northwest portion of the
PZ5 waters this morning according to the 12Z OPC surface analysis.
Meanwhile, high pressure persists west of the offshore waters
with an inland trough analyzed over northern California. Overnight
ASCAT passes supported northerly winds of 20 to 25 kt over the
northern California offshore waters between these two features.
With little variation in the global model guidance, no major
forecast changes were necessary this morning. Bumped up wind
speeds to 30 kt for the southeast portion of PZZ820 tonight
knowing the model winds tend to run a bit low here in this
pattern. There are currently no warning headlines in effect for
the offshore waters through Friday night.

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

00z global models in good agreement through the forecast period.
Will lean towards 10m winds from the 00z GFS for the wind grids
through the forecast period, which has good support from both the
00z ECMWF and the UKMET.

Low pressure expected to move N of the area today, dragging a
frontal boundary across the northern PZ5 waters. Latest
observations showing gusts to 25 kts ahead of the boundary and
this is expected to move into the northwestern portion of the PZ5
waters today. Boundary is expected to weaken as it moves across
the region, with winds expected to slowly diminish as the
boundary moves southeast.

High pressure then expected to build to the northwest of the PZ6
waters later today through Tue night and interact with the
coastal trough along northern and central California. Models
showing relatively stable atmosphere during this period, so will
rely more on the 10m winds which keep max winds to 30 kt. GFS
does indicate first sigma winds to 35 kt, so could not rule out a
few gusts to 35 kt for later today through Tue night, especially
in the coastal zones. Ridge begins to weaken Wed and Wed night,
allowing for winds to diminish.

Relatively quiet weather conditions expected for the end of the
forecast period as a weakening cold front moves into the region
Thu and Thu night, and high pressure rebuilds across the waters
Fri and Fri night.


.SEAS...ENP within a foot or two of current observations. Will
lean towards 00z ENP guidance for the wave grids through the
forecast period.


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



.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
     None.

$$

.Forecaster Reinhart/Achorn. Ocean Prediction Center.


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