Marine Interpretation Message
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325
AGPN40 KWNM 211417
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
617 AM PST Tue Feb 21 2017

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

At this time I do not plan on making any changes to the current
grids or associated text forecasts. There is still quite a bit of
uncertainty about how the system on Saturday evolves. The most
recent ASCAT from 05z indicates a small area of gale winds
funneling through the gap north of Kodiak. A large swath of ASCAT data
is missing along pacific coast across the eastern portion of the
offshore waters. Satellite pictures indicate that the gale
center is moving into the SW Oregon coast.

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

00z global models in good agreement through most of the forecast
period. Will populate wind grids from 00z GFS through the
forecast period.

1002 mb low off Point St George at 06z. Surface observations
showing coastal buoys gusting to gale force off Northern
California. Global models do indicate some potential for gales to
still exist at 09z in the adjacent offshore waters, and will
limit mention of gales to zone PZZ820 and for the beginning of
the first period. Winds should quickly diminish during the
morning hours as the low moves inland.

Models still showing a weakening low pressure system approaching
the Central California offshore waters Tuesday night into
Wednesday. Models are in good agreement in keeping the low west
of the offshore waters, with the low dissipating west of the area
Late Wednesday into Wednesday night.

High pressure builds in from the northwest and interacts with
coastal trough along Central and Southern California beginning
late Wednesday and lasting into Thursday night. Some of the
models showing low end gales in the 30m wind field off Southern
California during this time period. With stable conditions
expected will go with the slightly weaker 10m winds, keeping
winds to 30 kt.

Models indicating low moving southeast along the Pacific
Northwest coast Wednesday into Wednesday night, enhancing
northwesterly winds over the northern offshore waters. No gales
expected with this system.

Models continue to show a weakening low moving southeast from
the Gulf of Alaska Thursday and moving just west of the PZ5
waters Thursday night into Friday before dissipating. Models
still suggest another low developing near Vancouver Island
Thursday Night and moving south over the PZ5 waters Friday and
Friday night. 00z global models in good agreement with the track
of the low. Low then becomes absorbed by a second low moving in
from the west on Saturday. This merged low then is expected to
intensify just west of the Northern and Central California
offshore waters Saturday and Saturday night. Models are in decent
agreement with the placement of the low, and all models at least
indicating gale conditions with the low, with the GFS showing
storm conditions west of the offshore waters. Will bump winds to
35 kt for this package due to model consensus of at least minimal
gale winds with this system. Winds will most likely need to be
bumped up in upcoming packages if current model trends continue.


.SEAS...ENP within a foot or two of current observations. Will
populate wave grids from 00z ENP through the forecast period.
Will limit seas to 20 ft with strong low Saturday and Saturday
night.


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



.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
.PZZ820...Inner Waters from Point St. George to Point Arena...
     Gale Possible Saturday into Saturday night.
.PZZ920...Outer Waters from Point St. George to Point Arena...
     Gale Possible Saturday into Saturday night.
.PZZ825...Inner Waters from Point Arena to Pigeon Point...
     Gale Possible Saturday into Saturday night.
.PZZ925...Outer Waters from Point Arena to Pigeon Point...
     Gale Possible Saturday into Saturday night.
.PZZ830...Inner Waters from Pigeon Point to Point Piedras Blancas...
     Gale Possible Saturday night.
.PZZ930...Outer Waters from Pigeon Point to Point Piedras Blancas...
     Gale Possible Saturday into Saturday night.
.PZZ935...Outer Waters from Point Piedras Blancas to Santa Cruz Island, CA...
     Gale Possible Saturday into Saturday night.

$$

.Forecaster Shaw/Achorn. Ocean Prediction Center.



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