The forecasts are stable and the models are in agreement--cold and dry with strong winds downstream of mountain gaps.
Today we started with a large pressure difference across the Cascades (see temperature and wind forecast for 10 AM above). Cold temperatures and associated high pressure west of the Cascades. There was very strong wind acceleration in the only sea level gap across the Cascades...the Columbia Gorge...with winds at locations such as Troutdale reaching 30-40 mph.
The next act is beginning...the first in a series of upper level troughs is moving through and behind it there will be an influx of colder, continental air (see plot). Not the primo stuff...but cooler than we have had during the past several days. I have included a surface chart for later tomorrow...with cooler air and northerly flow moving south--there is a large pressure change at the forward edge of the cold air. There could be a few snow showers tomorrow morning with this...particularly over the western Cascade foothills...but nothing of any note.
A second upper disturbance moves through Sunday and an even stronger pulse of cold air, with strong easterly and northeasterly flow follows (see figure). Will be an interesting day. A huge gradient will be established over the Fraser River Valley and strong winds will push into Bellingham, with further acceleration down the western Strait of Juan de Fuca. You will see the famous Tatoosh easterly gales! At one time this area was known as the "graveyard of the north Pacific" due to these winds and the rocks. You have delicate plants...protect them. When the winds die down on Monday morning the temperatures could plummet on the western side into the teens in some locations. Maybe even colder Tuesday am. Good weather for plumbers--could have some frozen and bursting pipes.
And watch the action offshore! As the cold air moves over the relatively warm water there will developing cumulus activity...including showers. There will be lines of convection...should be impressive.
Monday and Tuesday will be cold and sunny. That's far enough to forecast...but remember...sometimes the most interesting weather happens when a cold spell ends. I won't even mention that unspeakable four letter word: S**W. Don't even think about it.