Hurricane Force Warnings in Effect
Pacific:  High Seas EP1 and EPI

North Pacific Marine Weather Discussion

[Printable Version]   [Alt Link/Previous Versions]   [Glossary]
AGPN40 KWNM 120836
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
1236 AM PST Tue Nov 12 2019

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

The overall pattern over the eastern North Pacific Ocean will be
slow to change over the next several days, with an upper level 
high pressure ridge persisting near and over the offshore waters
today into Wed. The ridge will then temporarily shift inland by 
Thu into Fri as the upper level flow briefly becomes more zonal 
over the region. Another upper level ridge will then re-develop 
over the eastern North Pacific Fri night into the upcoming 
weekend, with a cut-off upper level low developing near or just 
S of the southern California waters. 

At the surface, weak high pressure over most of the waters early
today will persist into Wed night, with a weak cold front 
crossing PZ5 waters today, stalling over Oregon waters early 
tonight, and then dissipating by late tonight. The surface high 
will shift inland over the Pacific NW early Thu, with an 
extension of the high remaining over central and southern 
California offshore waters. A cold front will then slide E into 
the outer portions of the offshore waters from Washington 
southward to the northern California during Thu. Any gale force 
winds associated with the front will likely remain N of the 
offshore waters, near and N of Vancouver Island. The front will 
reach the coast Thu night or early Fri and weaken. Surface high 
pressure will then expand over the waters during Fri into Fri 
night, with a warm front lifting N, and passing just NW and N of 
the offshore waters. The high will persist Sat and Sat night as
another cold front moves E into Washington waters Sat night. Any
gale force winds associated with this front will likely remain W
and N of the offshore waters during the weekend.

The 00Z GFS and 00Z ECMWF are in very good agreement over the
offshore waters during the next 3-5 days, and remain about in 
the middle of the overall 00Z model guidance. For the early 
morning package we will populate grids with an even blend of 
these two models today into Sat night across the waters. This 
will maintain continuity from past OPC forecasts as well, with 
hazard-level winds unlikely over the offshore waters into the 
weekend. Forecast confidence remains above average over the next
5 days. Some minor difference then develop later in the weekend 
into early next week, and we will trend the grids more toward 
the consistent 00Z ECMWF guidance for now and cap winds at 30 
kt.

.SEAS...Both the 00Z Wavewatch and 00Z ECMWF WAM guidance has
initialized fairly well over the offshore waters early this
morning, with sea heights ranging from near 8 ft over central
California waters, and over the NW and western Washington and
Oregon waters, to 4 to 5 ft or so over most of the southern
California waters and the far eastern Washington and Oregon
offshore waters. Both wave models have, however, initialized up
to 4 to 5 ft too low over waters well W and NW of the offshore 
waters based on the latest altimeter data, with seas up to 20 ft
or so occurring over the Gulf of Alaska. Both the Wavewatch and 
WAM remain fairly similar over the waters into Sat night, and we
will use a 50/50 blend of these two wave models during the next 
3-5 days, with little change from the past few OPC forecasts. A 
long period, around 20 seconds, W to NW swell train is still 
expected to reach the offshore waters Wed night and Thu, and 
persist into the weekend before the swell periods begin to 
shorten. 

Extratropical Storm Surge Guidance: N/A.

.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
     None.

$$

.Forecaster Mills. Ocean Prediction Center.