000
AGPN40 KWNM 152102
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
102 PM PST Sun Dec 15 2019

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

A very active weather pattern will dominate most of the offshore
waters during the next several days. As model agreement decreases
with time, forecast confidence will lower over the region as well
by the middle to end of the week.

Over the short term, the 12Z models remain on decent agreement
across the region into Mon night, and then differences once
again are noted by Tue night through the end of the week. We
prefer the 12Z GFS winds for tonight into Mon night across the
waters, with the latest ASCAT overpass indicate winds up to 30
kt off the southern California coast mainly near and S of the
Channel Islands. The 12Z GFS 10 meter winds align quite well
with the latest ASCAT passes. A cold front will approach the
waters from the W Mon into Mon night, with patchy gale force
winds expected to develop just ahead of the front, and holding W
of the waters into Mon night. Forecast confidence is above
average over the region into Mon night. By Tue and Tue night, we
will trend the forecast more toward the fairly consistent 12Z
ECMWF guidance, with gales spreading E with the cold front into
the outer offshore waters from northern California northward
later Mon night and Tue. The front will weaken as it approaches
the Pacific NW coast later Tue with gale force winds becoming
unlikely over the waters by that time. A low pressure area will
form along the southern part of the front off the central
California coast by later Tue. Forecast confidence for Tue is
near average.

Over the medium range, forecast confidence will range from near
to somewhat below average. We will remain closest to the 12Z
ECMWF for Tue night through Sat night across the waters as the
ECMWF remains the most consistent over the region during the
medium range. The low along the southern part of the front will
move from the central California waters Tue night towards the
central and southern California coasts during Wed as it weakens.
Most of the 12Z guidance brings winds to gale force in the SW
quadrant of this low as it crosses the central California waters
Tue night. We will go ahead and add a period of gales to the
outer central California zone of PZZ930 for Tue night as a
result. Further N, another cold front will slide E over
Washington and Oregon waters during Wed. For this package we will
keep maximum winds at 30 kt with this front as it moves over PZ5
waters on Wed. This front will weaken near the coast Wed night as
a warm front approaches Oregon and northern California offshore
waters from the SW. This front will quickly lift NE over Oregon
and Washington waters Thu followed by a cold front as a low forms
near Vancouver Island by later Thu. We will go ahead and add
gales to waters just ahead of the cold front on Thu, which at
this time, will be limited to Oregon offshore waters. Further S,
high pressure will become the dominate weather feature over most
of the California waters on Thu. High pressure will then prevail
over most of the central and southern California waters Thu night
as low pressure develops along the cold front to the W of the
northern California offshore waters. The low will approach the
outer northern California waters by later Fri as high pressure
remains over the central and southern California waters. The low
will finally push E over the northern California waters Fri night
as a cold front crosses PZ5 waters and the high to the south
moves SE to the southern portion of the southern California
waters. For now, we will add gale force winds possible to only
the inner southern Oregon zone, PZZ 815, for later Fri into Fri
night, and keep winds just below gale force outside of this zone
for now, until better model agreement develops over the next few
days. These gales appear to line up pretty well with the adjacent
coastal marine forecast from Medford later in the forecast
period. Additional adjustments to the forecast are likely over
the next several days and all marine interests should closely
monitor the latest OPC and coastal WFO forecasts.

Seas...Sea heights range from 10 to 14 ft over the waters this
afternoon, with the highest seas off the California coast. For
the afternoon package we will use an even blend of the 12Z
Wavewatch and 12Z ECMWF WAM for tonight into Mon night, and then
trend grids more toward the 12Z WAM thereafter to best match the
wind forecast.

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

.WARNINGS...Preliminary.

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

.PZ6 California Waters...
.PZZ920...Outer Waters from Point St. George to Point Arena...
Gale Tuesday.
Gale Possible Friday night.
.PZZ930...Outer Waters from Pigeon Point to Point Piedras Blancas...
Gale Possible Tuesday night.

$$

.Forecaster Mills. Ocean Prediction Center.