marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 730 am PDT Tue 22 Oct 2019
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
The 06z models and 12z models available thus far have remained generally consistent across the pz5 and pz6 offshore waters over the next several days. The GFS continued to be the strongest of the models with the northerly winds off the coast from Cape Blanco to near Point Reyes late Wed and Wed night. The best chance for any brief period of gale force winds is from about 00z to 06z Thu across the inner waters from Point Saint George to Point Arena. However, out of deference for the non-GFS model consensus, and like the previous pz6 forecast, we will continue to limit these winds to 30 kt at that time. Even the higher resolution 00z/06z namnest indicated maximum winds to 30 kt late Wed and Wed night. Confidence is then still well above average with the gale hazards expected toward the latter part of the forecast period Sat and Sat night. Overall, the previous wind and wave height grids appear reasonable and we will not be making significant changes from continuity in this mornings forecast updates.
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At 06z strong high pressure was in place west of the CA waters with a cold front pushing through the or waters. Winds across the or/WA waters were 10 to 20 kt. Between the strong high and a coastal trough in CA winds were 15 to 25 kt across much of the central CA waters. Elsewhere winds were generally 5 to 15 kt. Seas were 6 to 9 ft from the or waters to central CA waters. Seas across the southern CA waters were 7 to 10 ft and seas across the WA waters were 10 to 14 ft.
The 00z models are in above average agreement across the eastern Pacific through the forecast period. Gale hazards will be possible tomorrow night and again on Sat over the central/ northern CA offshore zones. With strong high pressure in place west of the waters a cold front will slide southward through the northern waters today and into the CA waters on Wed. With a CA coastal trough in place and building high pressure behind the front winds will be increasing in wake of the front across the central/northern CA waters. Global models have backed off on the winds with this event compared to the last several days leading to a decision to drop warning headlines for this period. Gales remain possible but much less likely with the only model support coming from the 00z GFS and rather limited at that. For the short term period through 00z Fri we leaned a bit more toward the 00z ECMWF which removed the gale conditions for the Wed night/Thu morning period.
High pressure will weaken on Thu with improving conditions before another cold front reaches the WA waters by Fri morning. Strong high pressure will build to the NW of the waters and drive a cold front southward across the northern waters on Fri and the southern waters on Sat. The strength of the high...1040 mb...combined with a CA coastal trough will generate a strong pressure gradient and winds will increase in response from the or waters to the central CA waters. Gale conditions will be possible beginning 12z Sat and continue into late Sat night across the northern CA and inner southern or offshore waters. There is above average confidence in these gales given the strong model agreement even at such long lead time. Conditions will improve sun through Tue as strong high pressure slowly weakens. For the longer range period we used a blend of the 00z ECMWF/GFS with good support from the rest of the global models for the gale conditions on Sat.
Seas...no recent altimeter passes over the waters but both wave models matching up well with marine observations at this time. We used the wavewatch through 00z Sat then used a blend of the wavewatch and ec wave for the rest of the period. Wavewatch was a bit too aggressive with wave heights late Wed into Thu because of the higher wind speed forecast for that period so blending in the ec wave brought that down to a reasonable level.
.Extratropical storm surge guidance...N/A.
.Pz5 Washington/Oregon waters... .pzz815...inner waters from Florence or to point St. George... gale possible Saturday into Saturday night.
.Pz6 California waters... .pzz820...inner waters from point St. George to Point Arena... gale possible Saturday into Saturday night. .Pzz920...Outer waters from point St. George to Point Arena... gale possible Saturday night.
.Forecaster Clark/krekeler. Ocean prediction center.