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000
AGPN40 KWNM 211521
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
725 PM EST FRI 21 FEB 2020

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

There is only one instance where any hazards are possible across
both the PZ5 and PZ6 waters through the forecast period, and
these hazards are likely over the northern PZ5 waters Sat night
and Sun. Versus previous runs, the past three runs of the GFS
have trended significantly stronger with the west to northwest
winds across the Washington waters, now showing winds reaching
storm force over the waters north of Cape Shoalwater. The 00z
ECMWF was further south with the low track compared to its
previous run, and as a result was also much stronger with the
winds over these northern zones. The 00z UKMET is now showing 35
to 45 kt winds over the outer waters north of Cape Shoalwater as
well. Given these trends, we have increasing confidence with
previously forecast gale hazards, and will also note that storm
force winds are not out of the question. The overnight wind
grids were adjusted higher versus yesterdays, and we may have to
further adjust them over the northern PZ5 with todays forecasts.
However, will wait for the full suite of 12z model guidance
before making any changes to the wind grids. Elsewhere over the
remaining offshore waters, the overnight model guidance was
generally consistent and overall remains in very good agreement.

---------------------------------------------------------------
...Previous Discussion...

ASCAT data remains out across the waters. The most recent
satellite pictures continue to show a weak pattern with a low
center W of the California waters slowly drifting S. Several
altimeter passes from 02-04Z indicates seas over the waters are
generally 10 ft or less with the maximum across the Washington
waters, which agrees well with current buoy observations. During
the upcoming week there will be a period from Sat night through
Sun where gales are likely across the northern PZ5 waters. All
of the 00Z global models indicate a strong area of low pressure
moving N of the region during the period, although the GFS is a
bit of an outlier and forecast the low further S and closer to
the Washington region. I opted to blend the CMC/UKMET/ECMWF Sat
night and Sun when populating the wind grids. the remainder of
the forecast period is rather benign as a ridge axis builds into
the Washington and Oregon waters, while a coastal trough
persists along the California coast. A couple of weak frontal
boundaries will move into the PZ5 waters and weaken as they
encounter the ridge axis. In general the global models are in
pretty good agreement throughout the forecast period, except for
some minor differences. I will populate the wind grids using the
GFS through 00Z Sun, then transition to a blend of the
CMC/UKMET/ECMWF through 06Z Mon. I will then use the ECMWF for
much of the remainder of the week through 12Z Thu before
finishing the period using the GFS.

Seas...Both the ENP and WAM initialized well across the region
at 00Z. I will populate the wave grids using a blend of the two
models throughout the forecast period.

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

.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
.PZZ800...Inner Waters from Cape Flattery to Cape Shoalwater...
     Gale Possible Sunday into Sunday night.
.PZZ900...Outer Waters from Cape Flattery to Cape Shoalwater...
     Gale Possible Sunday into Sunday night.
.PZZ905...Outer Waters from Cape Shoalwater to Cape Lookout...
     Gale Possible Sunday.

.PZ6 California Waters...
     None.

$$

.Forecaster Clark/Shaw. Ocean Prediction Center.



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