Sunday will certainly feel chillier as colder air had begun to filter in. The central Cascades, where a Winter Storm Warning is still in effect, may continue to see periods of heavy snowfall into the evening hours.
Foothills/Snoqualmie Valley: A convergence zone is expected to form, enhancing precipitation potential for a few hours later this evening. It still looks like there’s fairly good southerly flow aloft, so it may come in a bit too warm for snow, but the heavier showers are known to at least temporarily bring the snow level down (~500ft). The GFS model is showing a more favorable setup for this. I’d say there’s a 50% chance some might see snowflakes by the tail end of the Super Bowl tonight or later into the evening (after 8-10 pm), potentially lasting into the overnight hours.
But that’s the crux of it. For the last several days, we’ve seen the GFS model persistently call for a fair amount of snowfall in the foothills, tonight and over the coming days, while the Euro model, also advertising the colder air, but has been trending much drier with little precipitation chances, at least for the first part of the week ahead.
For Sunday evening/Monday morning, we’ll go with a base case of rain/snow mix with accumulations of trace-3” in the highest hills (e.g., Eagle pt., Wilderness Rim). If current GFS wins out, those accumulations look possible down to the Valley floor (~500 ft). Even the National Weather Service had been acknowledging the potential for ~2” around “North Bend” overnight.
The model forecasts divergence continues through much of the coming week. GFS calling for lingering snow flurries or even showers much of the week, while the Euro has us mostly dry.
The one thing models seem to agree on is that colder air is on the way, and much colder by Thursday or Friday, potentially dropping Low temperatures into the teens. Look at inland B.C. and the plateau’s of central WA (e.g., Mazama, Winthrop, Leavenworth). Below zero certainly a possibility there!
Looking at several models, I’d say upper teens/low 20’s are a real threat for Snoqualmie Valley later in the week.
If you saw our poll on Twitter last night, and you’ve made it this far reading:), I’ll reveal the answer (below).
Answer: Feb 10, 2019, was the last time Snoqualmie Valley saw Low temperatures dip into the teens. Many will recall that date wrapped up week no. 1 of Snowmageddon. ~20″ of snow had already fallen, beginning that Feb 3rd. Those two weeks in February would go on to accumulate 35+” of snow! By the way, all the other dates above except Jan 15 of last year were also nightly lows that reached into the teens. The rough average is 3 days a season that dip into the teens° in Snoqualmie Valley, but there are plenty of years that don’t see any days this cold.
This has been a relatively mild winter so far, dominated by gap winds where an offshore Low spinning counterclockwise blocks colder air from the Gulf of Alaska sliding down, as well as occasional atmospheric rivers that draw up moisture from the south. I might need to wrap those pipes later this week!
Have a great week and play today’s festivities safe!
[Originally published at Snoqualmie Weather blog. During active weather, follow more frequent updates @snoqualmiewx or on Facebook]
