marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 756 am PDT Sat Oct 21 2017
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
Forecast appears on to be on track for this update. Agree with the previous forecasters decision to continue the use of the ECMWF from Tue to Wed night as it has continued to maintain consistency for the last several days with the timing and strength of the low and fronts moving over the ridge. Will not make any major changes to the forecast.
----------------------------------------------------------------- Previous discussion...
Agreement among the 00z models is good over the forecast area for much of the forecast showing a pattern change from a progressive active pattern to the re-establishment of an amplified pattern with the eastern Pacific Ridge becoming dominant for the offshore waters by Mon while a series of upper shortwaves and associated surface lows and fronts move over the ridge. The 00z models generally support the GFS except for the Tue to Wed night period preferred the 00z ECMWF which has been consistent in the timing and strength of one of the surface lows and fronts moving over the ridge and into Canada, giving a cold frontal passage to the northern waters and cold advection and possible NW gales in the Washington waters Wed into Wed night and in the northern CA waters Wed night. In the nearer term a 2:1 blend of the 00z GFS 30m/10m winds appear to initialize well on the initial conditions with the fronts and associated gales in the pz5 waters today into tonight which appear in latest ascat passes. Will otherwise use the 00z GFS 10m winds for the forecast Sat night and beyound except for the 00z ECMWF for Tue to Wed night with its handlong of the northern system and front, boosted 10 to 15 percent in the cold advection Wed and Wed night.
.Seas...The 00z ECMWF wam appears to be handling the initial seas well but both models a couple of feet too low with initial large swell in the pz5 waters. Populated with the 00z wam through 18z today edited to increase swell by 10 percent as a better fit to the observations. After that model differences become small and used the 00z enp ww3 for the remainder of the forecast except for the 00z wam where the 00z ECMWF is used for winds.
.Extratropical storm surge guidance...N/A
.Pz5 Washington/Oregon waters... .pzz800...inner waters from Cape Flattery to Cape Shoalwater... gale today into tonight. Gale possible Wednesday into Wednesday night. .Pzz900...Outer waters from Cape Flattery to Cape Shoalwater... gale possible Wednesday night. .Pzz805...Inner waters from Cape Shoalwater to Cape Lookout... gale today into tonight. .Pzz905...Outer waters from Cape Shoalwater to Cape Lookout... gale today into tonight. .Pzz810...Inner waters from Cape Lookout to Florence or... gale tonight. .Pzz910...Outer waters from Cape Lookout to Florence or... gale today into tonight. .Pzz815...Inner waters from Florence or to point St. George... gale tonight. .Pzz915...Outer waters from Florence or to point St. George... gale today into tonight.
.Pz6 California waters... .pzz820...inner waters from point St. George to Point Arena... gale possible Wednesday night. .Pzz825...Inner waters from Point Arena to Pigeon Point... gale possible Wednesday night. .Pzz925...Outer waters from Point Arena to Pigeon Point... gale possible Wednesday night.
.Forecaster Sommerville/Bancroft. Ocean prediction center.