Marine Interpretation Message
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000
AGPN40 KWNM 260347
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
847 PM PDT Tue Apr 25 2017

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

Have not seen any recent satellite derived winds across the
offshore since about early afternoon. There was a ship
observation across the waters from San Clemente Island to
Guadalupe Island which showed gale force past several hours. QC
history indicates about 95 observations in the database with
about a plus 5.6 kt bias which if corrected shows about 30 to 33
kt. It seems more likely winds are to 30 kt in this area which
fits with GFE in this area. Elsewhere over the inner waters of
the srn CA waters winds are probably marginal gales up to 35 kt
this evening and should continue overnight in this area. Strength
of the winds will remain at least to 30 kt for Wed for this
area. Elsewhere over the offshore waters a warm front was lifting
NE over the ern WA waters with a cold front moving SE across the
OR waters. Strongest winds are to the E of the frontal system
and inadvof the cold front along the OR coast. Seas were to 12 ft
near the OR coast at 00Z which is about 3 ft higher than the
WWIII/ECMWF wam. Will likely adjust seas somewhat higher the GFE
values although main area of max seas is just E of the OR
offshore waters and should subside later tonight as front moves
SE. For the updated forecast will make a few changes, although
mainly with seas in the OR waters.


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

The ASCAT pass from 17Z indicates a swath of 30 kt winds along
120W. If gales have not already begun, I expect gales to start
vary soon. Further N, a well defined cold front is shown entering
the Washington waters. The 12Z global models are generally in
very good agreement during the upcoming week. The low pressure
trough that has been present along the southern and central
California coast will persist, periodically strengthening and
weakening during the upcoming week, although a small area of
gales will like continue during much of the time over the inner
offshore waters South of Point conception, occasionally reaching
the outer waters. The trough will expand North along the coast
after day 5, while gradually weakening below gale. Further North,
the overall patter will continue to be progressive during the
next 24 hours as a frontal boundary crosses the region, then
become blocked as a high pressure ridge builds NE over the PZ5
waters. I will populate the wind grids using a 50/50 blend of
the 10M/30M GFS through 12Z Thursday, then transition to the
ECMWF through 12Z Saturday. From 15Z Saturday through 12Z Sunday
I will use a blend of the 10M/30M GFS again. From 15Z Sunday
through 15Z Monday I will populate using the UKMET, before
finishing the week using the GFS blend again. I am using the
various models mainly due to some timing differences in the
Northern stream.

seas...Both the ENP and WAM ok throughout the forecast period,
although I give a slight edge to the WAM. I will populate the
wave grids using a blend consisting of 40 percent ENP versus 60
percent WAM.

.EXTRATROPICAL STORM SURGE GUIDANCE...n/a.


.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
.PZZ835...Inner Waters from Point Piedras Blancas to Santa Cruz Island, CA...
     Gale Possible Thursday night.
.PZZ840...Inner Waters from Santa Cruz Island, CA to San Clemente Island, CA...
     Gale tonight.
     Gale Wednesday night into Thursday.
     Gale Possible Thursday night into Friday night.
.PZZ940...Outer Waters from Santa Cruz Island, CA to 120W...
     Gale Possible Thursday night.
.PZZ945...Outer Waters from 120W to San Clemente Island, CA...
     Gale Possible Thursday night.

$$

.Forecaster Rowland/Shaw. Ocean Prediction Center.



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