Today felt a little “chilly” didn’t it? That’s because our daily average temperature actually fell below “normal” for the first time since January 8th!
Highs were only in the 40s for most areas west of the Cascades today as a neat little surface low spun its way down onto the Central Oregon coastline. It didn’t produce measurable rain in the vast majority of the metro area…the 8th consecutive dry day at PDX. Of course this month and the year so far have been much warmer than normal. Here’s the year to date anomaly across the USA…warm west of the Rockies and cool east.
The reason it’s been so mild the past 7 weeks is because upper-level high pressure has been persistent near or just offshore the West Coast of North America. That blocks storminess (a very dead start to 2018), and tends to keep cold arctic air to the east of us. Here’s a map from this past Tuesday, you see the big warm anomaly just to our west.
I’ve mentioned several times in the past few weeks that just a little movement of that ridging to the west would open up the door for colder systems to drop in over us from the north or northwest. Basically the “back door” would be open from the north. It now appears that, at least for the next 10 days, the ridge WILL push a little bit farther west and positioning means everything in this case.
This means that winter is coming back. No, I’m not predicting some sort of all-day snow/ice storm for the lowlands. But I do think we’ll be colder than normal for this time of year and hard freezes will return. Plus depending on how moisture interacts with the colder air, the possibility of lowland snow.
KEY POINTS FOR THE NEXT 7-14 DAYS
- I sure won’t be “forking winter” anytime soon. That would be dangerous in a La Niña year before the end of February. It is in these winters that we often get a late/wet low elevation snowfall. Or several near-misses in the lowlands in late February or early March.
- Don’t unwrap your pipes yet, just wait until we get through this next cool period to make sure we don’t have 20 degree or colder temps still on the way
- Forget about the 55-65 degree days, they won’t be back for the next two weeks.
- If you use studded tires, I sure hope you didn’t take them off yet. Leave them on for now. The chance for snow at the lowest elevations is the highest we’ve seen since Christmas
- That said, nothing screams SNOWSTORM right now, except my typing. But this is the pattern where a snow event in the lowlands could suddenly appear just 3-4 days away.
The first system slid down the back side of the ridge and over us today. The 2nd comes through on Wednesday, and then all models (led by the ECMWF) show a 3rd deeper/colder trough digging down right over Cascadia on Saturday as the ridge retrogrades or “backs up” to the west. Then long-range modeling shows a 4th next Monday/Tuesday.
Push the ridge even slightly farther west and we’d finally be in a typical La Niña pattern. But so far this change for next weekend and early the following week is still a bit drier than normal since the ridging is sticking relatively close to us. Note the precipitation average for Salem on the ECMWF ensembles is only about 1.50″ in the next two weeks (lower blue bars):
I don’t see a good setup for snow in the lowlands in the next 7 days FOR NOW, although somewhere around Sunday-Tuesday appears to be the our first chance for a brush with the white stuff as colder air arrives and moisture leaves. That could easily be a “snow in the hills” but only “flakes in the air below” sort of setup. That will likely be enough to trigger snowflakes on your weather app.
One really good bit of news is that Wednesday’s system and the cold trough next weekend should bring a couple nice dumpings of powder to the Cascade Ski Areas. Skibowl is mainly closed and it’s a little thin at the lowest parts of Timberline/Meadows. We might get that taken care of by next Sunday. See my 7 Day Forecast for Government Camp:
Nice cold temps and fresh snow just in time for the 3 day holiday weekend.
In the short-term, enjoy the sunshine and seasonal temps the next two days. We’ve got some bright weather ahead!
Chief Meteorologist Mark Nelsen