Marine Interpretation Message
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AGPN40 KWNM 242119
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
119 PM PST Tue Nov 24 2020

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

For the wind grids, will lean towards 12z GFS through 12z Sun,
then switch towards the 12z ECMWF after 12z Sun and lasting
through the end of the forecast period 12z Mon.

Cold front currently moving across the northern offshore waters.
Most of the latest model guidance showing winds below gale force
in the cold air advection behind the cold front. Latest ASCAT
pass does not show much directly behind the cold front. Hesitant
on taking gales out of the forecast at time, especially in cold
air advection. Will keep mention of gales for a brief period
just behind the front tonight.

Guidance has continue to trend weaker with the associated low
pressure moving in from the northwest tonight and Wed. Latest GFS
really the only guidance that shows gales moving into the
northern offshore waters Fri, with remainder of the the guidance
weakening low enough for winds to be below gale force as it moves
into the offshore waters. Will lean towards the GFS solution at
this time which has winds to 35 kt moving into the northern
offshore waters for a brief period on Fri before weakening to
below gale force.

Next front slowly approaches the offshore waters Thu into Fri as
a high pressure ridge sets up across the offshore waters. Ridge
weakens enough on Fri to allow the front to move into the
offshore waters. Guidance does indicate gale conditions in the
southerly flow ahead of the front as it approaches, but as with
the previous fronts, weakens the front enough for winds to fall
below gale force as the front moves into the area. Front moves
into the area Fri into Sat, then lifts north as a warm front Sat
night into Sun as the next cold front approaches. Latest
guidance again showing gales ahead of the front as it approaches
the region. Some of the guidance does show a few gales ahead of
the front as it moves into the offshore waters on Sun, but will
limit them to 30 kt for now. Latest GFS develops a low along the
front over the offshore waters by the end of the period 12z Mon
with gales associated with it. Will lean towards the ECMWF
solution for this system as it only indicates a frontal passage.

To the south, winds to 30 kt are possible Wed and Wed night as
coastal trough develops and interacts with high pressure to the
northwest. Pattern expected to slowly weaken Thu into Fri.


.SEAS...For the wave grids, will lean towards 12z ENP version of
wavewatch through 12z Sun, then switch towards the 12z ECMWFWave
after 12z Sun and lasting through the remainder of the forecast
period 12z Mon. Guidance continues to trend lower on seas coming
in from the northwest with the strong low over the Gulf of Alaska
that approaches the offshore waters tonight and Wed. Models have
been advertising for the last couple of days seas at or slightly
above 30 ft moving into the offshore waters Wed, but now they
are advertising mid to upper 20`s. Will go with 27 ft max over
the far northern offshore waters for now, but may need to be
lowered more if current trends hold.


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


.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
.PZZ900...Outer Waters from Cape Flattery to Cape Shoalwater...
     Gale Wednesday.
.PZZ815...Inner Waters from Florence OR to Point St. George...
     Gale tonight.
.PZZ915...Outer Waters from Florence OR to Point St. George...
     Gale today.

.PZ6 California Waters...
.PZZ920...Outer Waters from Point St. George to Point Arena...
     Gale tonight.

$$

.Forecaster Achorn. Ocean Prediction Center.


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