827
AGPN40 KWNM 180324
MIMPAC

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

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

At this time I don`t plan on making any changes to the grids or
associated text forecasts. The most recent ASCAT indicates mainly
winds 5-15 kt across the region, with occasional winds to 20 kt.
Maximum winds to 25 kt are located in the coastal waters along
the northern California coast.

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PREVIOUS DISCUSSION...

The 18z surface analysis indicated a weakening cold front over
the Oregon coastal and offshore waters, with a weak high pressure
ridge across the northern and central California waters.
Satellite imagery and lightning data continue to indicate
convection associated with a mid/upper level disturbance west of
the central and southern California waters with decent amount of
lightning strikes. Several ascat passes from around 18z indicated
winds were 20 kt or less over the offshore and coastal waters.

The 12z models continue to be in very good agreement during the
short term period through about 12z Friday, with differences
appearing shortly thereafter and continuing through the period.
For the immdiate short term period, the mid/upper level
disturbance to the west of the central and southern California
waters will move east tonight and inland Wednesday. Will continue
to mention scattered thunderstorms over the southern portion of
the central California waters and northern portion of the
southern California waters tonight as system moves east. Then the
focus shifts north to the Washington/Oregon waters for remainder
of period. The first of several strong systems will move across
the Washington and Oregon waters later tonight through Wednesday
night. The 12z models are in very good agreement with the timing
and placement of gales with this system, and plan on using a
50/50 blend of the GFS 10m and 30m winds. This will result in
very few if any changes from previous forecast. Then looking
ahead to Friday and beyond, another strong system if forecast to
once again affect mainly the Washington and Oregon waters.
Similar to the past few runs, the GFS remains a more progressive,
and slightly further south outlier compared to the other global
models. For this reason, plan on using the 12z ECMWF beginning
about 15z Friday and continuing for the remainder of period. In
summary, will use a 50/50 blend of GFS 30/10m winds through 12z
Friday, then ECMWF.

.SEAS...The 18z sea state analysis indicated that observed seas
were about 1 to 2 ft higher than the WaveWatch III over the
Washington and Oregon inner and coastal waters, with the ECMWF
WAM closer. Otherwise, the values over the remainder of the area
were close to the WaveWatch III. For the wave grids, plan on
starting initially with ECMWF WAM values, then transistion to
50/50 WaveWatch III/WAM blend overnight through 12z Friday. For
the remainder of period will use ECMWF WAM values.

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

.PZ6 California Waters...
None.

$$

.Forecaster Shaw/Kosier. Ocean Prediction Center.