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000
AGPN40 KWNM 271411
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
711 AM PDT Thu Apr 27 2017

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

No significant changes to the forecast or headlines anticipated
at this time.

12z surface observations showing gusts to near gale force in zone
PZZ840, with gusts to near 40 kt in the adjacent coastal waters.
Latest model guidance does indicate at least at 30m winds to
gale force over portions the southern California offshore waters
later today and continuing into Friday. Latest model data also
showing stable conditons over the region through this time
period, with these 30m winds unlikely to mix to the surface as
sustained winds. However, can not rule out gusts to gale force
in the warning area as current observations already showing gusts
to near gale force in portions of the southern California
offshore waters. Think likeliest area of gales will be in zone
PZZ840 with other zones in the warning area not as likely or will
be brief in duration.

SEAS...ENP within a foot or two of current observations.

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

Over the offshore waters this morning There was an ASCAT pass at
04Z with a swath across the ern areas of the srn CA waters E of
121Z. Strongest winds were to 30 kt S of Pt Conception. There was
another ASCATB pass at 05Z over the same area of srn CA waters E
of 120Z with the strongest winds to 30 kt.

At 06Z High pressure remains centered to the W of the central and
srn CA waters. Strongest winds to 30 kt continue to be across
the inner waters of the srn CA waters and should slowly expand N
today as coastal trof over srn CA develops and extends over
central CA. Area of gales should develop this afternoon over the
inner waters of the srn CA waters with the models showing the
strength of the high pressure and coastal trof becoming somewhat
weaker later tonight through Fri night. By Sat a cold front moves
E and SE across the WA/OR waters while weakening. The GFS/ECMWF
are in close agreement with the strength of the winds to 30 kt in
advance of the front. UKMET tracks associated low pressure E and
just N of the WA waters. Believe the GFS/ECMWF is more likely
with the low pressure further N of the area. The GEM model while
stronger with the cold front that moves E over waters is similar
with low pressure further N as depicted by the GFS/ECMWF. By Sun
high pressure moves over the nrn offshore waters and gives way to
a warm front that moves E into the WA/OR waters late Mon and Mon
night. Elsewhere over the CA waters the area of high pressure
and the coastal trof are similarly depicted by models as
restrengthening late Sat night through Mon with a resulting
increase of winds over the central CA waters.

For the grids will be favoring the GFS through the forecast
period with close agreement with the ECMWF.

.SEAS...Both the WWIII and ECMWF wam are in close agreement
through the forecast period. Will use a 50/50 blend of their
output through the end of forecast.


.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 tonight into Friday.
.PZZ840...Inner Waters from Santa Cruz Island, CA to San Clemente Island, CA...
     Gale today into Friday.
.PZZ940...Outer Waters from Santa Cruz Island, CA to 120W...
     Gale tonight into Friday.
.PZZ945...Outer Waters from 120W to San Clemente Island, CA...
     Gale tonight into Friday.

$$

.Forecaster Achorn/Rowland. Ocean Prediction Center.


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