Quick Wednesday evening update: Cold air is arriving with windy night ahead

There’s a change in the air this evening...much colder! Easterly wind is now pumping cold modified arctic air through the Gorge and into the Willamette Valley. It’s rare to see temperatures drop in the afternoon under sunshine at PDX, but it happened today. 42 at 1pm to 35 at 3pm as the cold east wind started blowing. 6pm temperatures are dipping into the 20s in the metro area, headed down to around 20 for most of us by morning.

It’s 16 degrees colder at 6pm compared to yesterday at this time. You can see the big cooling surging south on this 24 hour temp change chart

KEY METRO AREA POINTS THIS EVENING

Most of NW Oregon and SW Washington is under a Winter Storm Warning. This is mainly for freezing rain, but it’ll start with flurries and/or ice pellets for some of us, especially around the Portland metro area.
Tomorrow will be the coldest day we’ve seen in about 6 years. Remember the frozen days (but sunny) following the big snowstorm in January 2017? I remember the frozen ruts on I-84 well... That’s the last time we’ve seen a daytime high temperature below 30 degrees. Tomorrow we will only reach the mid 20s. We hit 11 degrees during that cold spell, but we won’t be getting that cold this time around. No clear, cold nights ahead. Household (interior) pipes should be mainly safe because we won’t see the really cold stuff for long, just a day or so.
Precipitation arrival of course is a BIG deal for all of us. Right now it appears we’ll see a few flurries or ice pellets starting to show up mid-afternoon. All models imply this will be extremely light, and we’ll need to wait until AT LEAST 5pm for that to change to liquid (then freezing) rain. It WILL be cold enough that anything will freeze on contact, except for flurries which will just blow around in the strong wind of course. At some point after 5pm roads will start icing up as steady freezing rain arrives. Assume all roads will be icy by 10pm at the latest.
IF YOU WANT TO PLAY IT SAFE, GET ALL YOUR ERRANDS DONE BY NOON OR SOON AFTER TOMORROW
Then an ice storm begins...from tomorrow evening through Saturday night I expect wave after wave of rain or showers. Ice glazing will occur at any one location until southerly wind arrives and pushes temperatures above freezing. Portland will be locked in ice all day Friday, through Friday night, and at least into Saturday morning. I expect 1/4″ to 1/2″ ice glazing by Saturday morning.
For areas that do not rise above freezing most of Saturday, up to 1″ ice could “accrete” since models imply a wet surge of rain passes overhead that day. That’s most likely in east metro areas close to the Gorge.
There are hints a warming southerly wind could scour out most of the cold air in the metro area Saturday afternoon and as we head into Christmas Eve itself. I have real doubts that will actually occur, but no one will complain if we warm up early right? Just don’t plan on clear roads (yet) for later Saturday. If we get lucky, roads will be much better west/south metro Saturday afternoon/evening.
Metro area should be clear of ice and travel should be fine anywhere away from the Gorge on Christmas Day (fingers crossed behind my back).

This sums up the next 3 days well

What about the Willamette Valley? Expect dramatic warming Saturday, but just about all the valley from Salem northward to Longview should stay frozen Friday. Luckily we’ll see a MAX of 1/2″ ice, none of the 1″ or 2″ devastating icing we saw over Valentine’s Day in 2021

As mentioned in last night’s blog, the north coastline will see icing tomorrow evening through early Friday morning, but then southerlies will take over. A very brief event out there.

And of course the Columbia River Gorge will be frozen THROUGH CHRISTMAS DAY.

The one strangely good bit of news for travelers? The Cascades! Cold air will still poking through the passes tomorrow night through Friday morning. This means 4-6″ snow tomorrow night, but then a period of freezing rain in the passes Friday morning. After that, warm air takes over with rain at times through at least Tuesday.

No travel concerns up there over the holiday weekend. Central Oregon is warming quickly Friday afternoon as well. Yes, Portland will be in an ice storm Friday and Saturday morning while Bend basks in 50 degree air!

That’s it for now. Blog postings might be more infrequent the next two days because I’ll be on TV a lot. You can catch me there each late afternoon and evening tomorrow and Friday.