Marine Interpretation Message
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000
AGPN40 KWNM 181407
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
607 AM PST Sun Nov 18 2018

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

Mainly light winds currently in place across most of the offshore
waters will continue into tonight. A cold front is still expected
to move across the pz5 and northern pz6 waters late Tuesday into
Wednesday. Low pressure moving north across the pz5 waters along
the front will be strong enough to produce winds up to 30 knots.
At this time will continue to keep conditions just below gale
force. Another stronger low will then move into the northern pz5
waters by Thursday. For now will continue to keep winds just
below storm force across the offshore waters with this low. The
low will then move inland over southwestern Canada by Friday
night. For wind grids will continue to use the current grids
throughout the forecast period. Current warnings look reasonable
and few changes should be needed on the next offshore waters
forecast.

For wave height grids will also continue to use the current grids
throughout the forecast period.

Extratropical storm surge guidance...n/a.

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

High pressure is located just north of the Washington offshore
waters this morning while a low pressure trough extends across
the northern California zones. Between these features, ASCAT wind
retrievals between 0430-0530 UTC supported east-northeast winds
20 to 25 kt across the central PZ5 waters. Elsewhere, offshore
winds remain less than 25 kt as another surface ridge prevails
over the southern California waters.

Based on the 00Z guidance, no major changes were made to the
forecast or warning headlines with this package. Weak low pressure
will approach the southern PZ6 waters Mon/Mon night, but the 00Z
models keep winds 25 kt or less before the low dissipates early
Tue. The 00Z GFS remained consistent with prior runs during this
period and was the preferred solution today through Mon night.

A frontal wave will develop along a cold front approaching our
northern waters Tue, and this low will lift north across the PZ5
zones Tue night into Wed. While marginal gales remain possible
with this system according to the 00Z GFS, the 00Z ECMWF/UKMET
both trended weaker with winds below gale thresholds. Given run-
to-run variability noted in the guidance, it seems prudent to
side with the weaker 00Z ECMWF winds beginning on Tue. Similarly,
most of the 00Z models trended farther north with the strong low
and frontal system to impact the PZ5 waters Thu and Thu night.
The GFS solution is a clear outlier, while the ECMWF matches up
fairly well with our previous forecast. Therefore, we have
transitioned our forecast winds towards the 00Z ECMWF from Tue
through Thu night with minor adjustments to maintain warning
continuity. Gale warnings remain in effect Thu and Thu night for
all our offshore zones north of Point Arena, CA.


.SEAS...Buoy 46089 reported seas to 9 ft at 06Z within the 20 kt
east-northeast flow described above. The 00Z Wavewatch and ECMWF
WAM were both too low in this region, so the near term grids
were hand-edited to match our sea state analysis. Otherwise, the
00Z Wavewatch seas were favored today through Mon night. Similar
to our winds, the wave grids were transitioned to the 00Z WAM Tue
through Thu night.


.EXTRATROPICAL STORM SURGE GUIDANCE...No significant positive
surge events are expected over the next few days.



.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
.PZZ800...Inner Waters from Cape Flattery to Cape Shoalwater...
     Gale Possible Thursday.
.PZZ900...Outer Waters from Cape Flattery to Cape Shoalwater...
     Gale Possible Thursday into Thursday night.
.PZZ805...Inner Waters from Cape Shoalwater to Cape Lookout...
     Gale Possible Thursday.
.PZZ905...Outer Waters from Cape Shoalwater to Cape Lookout...
     Gale Possible Thursday.
.PZZ810...Inner Waters from Cape Lookout to Florence OR...
     Gale Possible Thursday.
.PZZ910...Outer Waters from Cape Lookout to Florence OR...
     Gale Possible Thursday.
.PZZ815...Inner Waters from Florence OR to Point St. George...
     Gale Possible Thursday into Thursday night.
.PZZ915...Outer Waters from Florence OR to Point St. George...
     Gale Possible Thursday into Thursday night.

.PZ6 California Waters...
.PZZ820...Inner Waters from Point St. George to Point Arena...
     Gale Possible Thursday into Thursday night.
.PZZ920...Outer Waters from Point St. George to Point Arena...
     Gale Possible Thursday into Thursday night.

$$

.Forecaster Nolt/Reinhart. Ocean Prediction Center.


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