Visibility really dropped on Wednesday, December 4th, as the fog rolled in. You can see why this happened (from the chart below) – as the day rolled on temperature and dew point nearly converged.
Fog can begin to form when the difference between air temperature and dew point is less than ~4° F. Water vapor condenses into tiny liquid water droplets that are suspended in the air.
I was driving through downtwon Snoqualmie last night and the sky looked eerily red and gray, like something out of Stranger Things. I gathered it was due to reflection off water vapor from the mix of Christmas lights in the surrounding area, as well as the field lights that were on at Mount Si High School.
The fog also made for some really cool Christmas light reflections in my neck of the woods.
As for the rest of the week, another pressure gradient should form over the Cascades bringing back our beloved Snoqualmie Valley gap winds – probably beginning later today (Thursday). It should be weaker vs. last Sat/Sun, maybe with gusts to ~30 mph this time around, but possibly persisting into Saturday morning. This is due to a big Low off the the Washington coast slowly sliding towards Southern Oregon / Northern California.
Weather models are more in conflict about rain for Snoqualmie/North Bend going into the weekend. However, there at least appears to be showers. The brunt of the latest storm again will be headed for southern Oregon and California.
Looking out a week, it does look like the jet stream will point more at us by December 11th or 12th. No alert at this point for a big shift toward colder or wetter, just a little less mundane weather for this time of year perhaps.
It’s too early to tell if this will bring a needed dose of mountain snow to our lower passes (e.g. Snoqualmie) or if it will pull in too much warm air from the southwest. Let’s hope for the former.