231
AGPN40 KWNM 231422
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
722 AM PDT Fri Jun 23 2017

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

Coastal low pressure trough has continued overnight weakening
trend and northward shift, and now lies along the far northern CA
and Oregon and Washington coasts. The coastal trough has also
shed a weak surface low centered near 34n126w / 1008 hPa along
the outer fringes of zone 935.

Buoy and ship obs are sparse in the vicinity of the strongest
pressure gradients, but as expected, the few in the area have
reported a steady decline in surface winds and gusts overnight
into this early morning. Most notably buoy 46015 just off Cape
Blano was reporting 23g29 at 12z. Recent 12z HRRR and 12z 4km
NAM guidance both initialized winds 30 kt or below, and overnight
guidance from the UKMET and ECMWF both suggested similar below-
gale winds at 12z this morning.

Based on current observations, forecast trends, and recent model
guidance, feel comfortable scrubbing the ongoing gale warning
and removing all headlines from the grids. The previous forecasts
ended the headline at 18z later this morning, so this does not
represent a major forecast change in the update. Otherwise, no
problems with the ongoing grids through the end of the period Tue
night. Will re-evaluate entire forecast with upcoming 12z global
suite.

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PREVIOUS DISCUSSION...

The ASCAT pass from 05Z indicates gale conditions across the
northern California waters, extending to the far SE portion of
the Oregon waters. South of Point Reyes the winds are variable 15
kt or less. An altimeter pass from 04Z shows seas to 18 ft across
the California waters. The 00Z global models are all in very good
agreement during the upcoming week across the offshore waters.
The forecast philosophy hasn`t changed in the past several days.
The pressure gradient across the northern California waters that
has been producing gales has started to relax overnight. The
areal extent of the gales have diminished somewhat, an will
continue to do so over the next couple of days. I expect gale
winds to linger into this morning before diminishing to 30 kt
this afternoon. Seas will continue to slowly subside across the
region as well. Much of the region will diminish to winds less
than 15 kt, the exception being across the PZ5 waters which will
maintain a northern gradient 15-25 kt throughout the remainder of
the week. Late in the week the coastal trough will begin to
strengthen once again, increasing winds to 25-30 kt over the
inner waters late in the period. I will continue the trend of
populating the wind grids using the 10M GFS throughout the
period.

Seas...both the ENP and WAM initialized well across the region
for the most part, and am expecting the models to perform well
this upcoming week. I am populating the wave grids using the ENP
throughout the forecast period.

Extratropical storm surge guidance: n/a.


.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
None.

.PZ6 California Waters...
None.

$$

.Forecaster Collins/Shaw. Ocean Prediction Center.