An interesting period of ahead, with some twists on the cold air invasions of the past. But first lets review what has happened.
Yesterday, cooler air moved in behind an upper level trough of low pressure. This trough forced a low level transition to northerly flow and enough upward motion to create a narrow band of precipitation that moved southward yesterday afternoon...with a few hundredths of an inch of rain (and even some very, very light snow in higher locations). The models underplayed this feature a bit, which is not uncommon. (this is an issue some of us are working on--there is a deficiency in the model precipitation physics that causes very light precip to evaporate too readily before it hits the ground).
With general clearing behind the band, temps fell last night, with temps dropping into the mid and even low 20s away from the water. (see graphic). And fog reformed in the south Sound. I should note that such fog is very dangerous..capable of icing roadways significantly. Remember--black ice on the roadway is the number one weather killer in our state!
Today will be cool (temps in the upper 30s to lower 40s) and there will be some sun after the fog burns off. But the big act is coming later today.
A second upper trough will through tonight (see graphic) and behind it REALLY cold air will move in and very strong winds will hit certain locations. Cold air will surge across the Cascades with a strong easterly and northeasterly component. As the air pushes up the eastern slopes of the Cascades there will be light snow (see graphic) and as the air pushes through the Fraser River Valley strong winds will hit NW Washington..passing through or just north of Bellingham, over the San Juans and Gulf Islands and then directly towards the NW Olympics (see graphic).
The air, which is really quite dry, will pick up a little moisture over the water (not that much) and will be forced upwards by the NE Olympics..the result will be snow--several inches easily. Now most of this will be in the foothills behind the Sequim to Port Angeles area--the question is how far to the water will it spread...certainly will decrease rapidly toward the water. But you can't feel sorry for these folks...they enjoy the best weather in the region and they need to share in the wet wealth once in a while. (My NW weather book has a lot of material on the Sequim snows and the Fraser gap flows if you want to learn more. )
Winds will increase down the Strait and will be quite strong at its eastern entrance near Tatoosh. We are talking about sustained 30-40 mph with gusts above 50 mph in the windy locations I just noted. The famous Tatoosh easterly gales. This area used to be called the "graveyard of the pacific" and for good reason.
Cold air--but not quite as cold as that coming through the Fraser--will push across the Cascades under strong easterly flow. And on Sunday western Washington will have a cold "moderated" arctic air mass over us. The strong easterly flow will make sure we will be clear.... lots of sun, with winds over the Sound from the northeast to east. Winds over the Cascade crest will be savage. I would not ski on Sunday..the conditions will be too severe. We are talking about wind chill temps WAY below zero.
Highs in the 30s over the lowlands.
Then comes plumber's paradise. With cold air in place and winds dying down, we will see very cold lows on Monday AM (see graphic). Teens will not be unusual in western WA. I am going to go out in an hour and bring in all my deck plants and mulch everything vulnerable. And disconnect all your hoses on the outside of your house or apartment. You know the drill.
But the fun doesn't end. We will stay cold (moderating a bit) next week. No significant precipitation in sight and California is going to get hit hard by heavy rain and potential flooding (something that often happens during El Nino years). But that is another story.
Monday will be cold and sunny..and Monday night and Tuesday morning will be also very cold. Eastern Washington will be savage...with temps dropping into the single digits all over the place on Monday morning.