marine weather discussion for N Pacific Ocean NWS ocean prediction center Washington DC 203 PM PDT Thu Aug 22 2019
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Pacific N of 30n and E of 150w.
A low pressure trough along the California and southern Oregon coast will continue to amplify through Friday. As the trough expands northward, the pressure gradient will tighten resulting in increasing north to northwest winds tonight from Pigeon Point to Cape Blanco. Gale force winds and/or gusts appear most likely through tonight from Point Arena to Cape Blanco. We have above average confidence that these stronger winds will remain within 60 nm of the coast as short-range forecast models are in decent agreement.
The 12z models remain in decent agreement through the forecast period as well with respect to surface and upper level feature across the waters. While high pressure will remain anchored to the west of the waters through the weekend, a weak cold front will drop southward into the Washington waters Friday night. This boundary will then weaken and eventually dissipate Saturday into Saturday night over the northern offshore waters. Well to the south of the waters, Tropical Storm Ivo is forecast to continue to move to the W-NW through late week. The cyclone is forecast to weaken through the weekend as it encounters much cooler SST. The models generally agree that winds will top out around 20 kt over the far southern portion of pzz940-pzz945 as the remnants of Ivo approaches. The next threat for gales beyond this evening appear to be early next week off of the southern Oregon coast. However, confidence is marginal with the GFS much more aggressive with wind speeds compared to the ECMWF. With this, will use a blend of the 12z GFS and 12z ECMWF in the medium range.
.Seas...The latest wavewatch and ECMWF wam initialized well over the eastern Pacific this afternoon. However, the wavewatch indicates higher wave heights both off of the Oregon coast and across the far southern waters early next week as a result of stronger winds generated by the GFS. Thus, will blend the two models at this time in the medium range and monitor for better consensus in the coming days. Depending on the intensity and track of Ivo, will also need to monitor for increased southerly swells that may potentially impact the Southern California coast early next week.
.Extratropical storm surge guidance...N/A.
.Pz5 Washington/Oregon waters... None.
.Pz6 California waters... None.
.Forecaster Gass. Ocean prediction center.