It’s is really cold out there this evening. Peak gusts have been in the 30-40 mph range across much of the metro area this evening.
Not only is cold air pouring through the Gorge, but this evening cold air is pouring right over the Cascades and down the west slopes into the foothills too. That means just about all of us are getting the wind, even the normally calm areas. The past two hours PDX has gusted to 41 mph. The airmass has cooled a couple degrees in the past 24 hours too.
The strong wind is due high pressure east of the Cascades and an approaching low pressure system moving toward southwest Oregon. Almost all the snow stays south of Salem the next 12 hours, but it’s quite a snowstorm right now from Roseburg all the way down into California. Even Medford is getting a snowstorm!
Winds will back off dramatically after daybreak Wednesday and go almost calm by Thursday morning. We’ll be left with sunny/calm/chilly weather for both Thursday and Friday. As a result I raised high temperatures another degree or two and brought lows down to around 20 in the city.
Not too much has changed for the general transition this weekend from cold and dry to mild and wet. What hasn’t changed is that I’m quite confident by late Sunday most of us in the metro area will be done with frozen precipitation.
What else do I see?
- Arrival of precipitation has been pushed back to later Saturday or even Saturday evening.
- The chance of snow has gone downhill dramatically. All models are pushing a warm layer of air inland at the same time as the precip arrival later in the day. The GFS is most bullish with this. It says we only have a very shallow layer of cold air right in the immediate metro area only. ECMWF is colder in general at the surface, more likely since east of the Cascades is snow-covered and that air will still be moving out into the metro area from the Gorge.
- There’s a significant chance of icy roads in the metro area Saturday night and into Sunday morning. Even a big enough chance to get the FOX12 Holiday Party rescheduled! Luckily I’m still employed…poor timing on that one.
I love this graphic from the ECMWF; it tells the story well. It’s the forecast total snow accumulation through the period over Portland. Each run of the model (it runs twice per day) over the past 5 days is shown as one line. Oldest run is the top line, this morning’s run is the bottom line. Look at Saturday/Sunday (hour 108 to 132)…as we’ve gone through the past 5 days the model has pushed more and more warm air aloft over us, dropping the snow chances very low. Pretty good way to display 5 days of model information eh?
Stay warm out there tonight and tomorrow, at least we’ll be slightly warmer, lose the wind, and keep the sunshine for Thursday and Friday.
Chief Meteorologist Mark Nelsen