I’m currently in Boston for the 100th annual American Meteorological Society conference, and let me tell ya; snow was the very last thing on my mind today. We hit an astonishing 70o degrees today, absolutely smashing the previous daily record of 62. This was only the third time since 1872 that Boston hit 70 in January. But while the locals may be happy for the unusual warmth, I know that a significant proportion of my fellow weather geeks at this conference were hoping for an apocalyptic Nor’Easter and full-on societal collapse. Next year’s conference is in New Orleans, but hey – if Boston can hit 70 in January, New Orleans could certainly see a flurry or two come 2021.
Speaking of snowpocali, the lowland snow threat is looking less substantial than feared earlier for the Pacific Northwest. But I expect many places will still see snow and that we’ll see some of the coldest weather in years, and the favored spots like the Bellingham, Portland, and the Cascade foothills will have to deal with brutal offshore winds due to steep pressure gradients between the arctic high over British Columbia and the Interior West and much lower pressure offshore.
A couple key points, in case you’ve got a life to live and don’t feel like reading my Saturday night ramblings:
- Rainy tonight and tomorrow morning, becoming much colder tomorrow afternoon as an arctic front moves south from BC.
- Expect snow along this front for Western Washington – trace-3″ seems likely most locations. No snow threat Sunday/Monday for Western Oregon lowlands
- Much more could fall in a Puget Sound Convergence Zone in North King/South Snohomish Counties.
- Any snow that falls over Western WA Sunday/Monday will not melt until Thursday and could have significant travel impacts.
- Portland and the Willamette Valley may see some wet snow Monday night/Tuesday morning but few impacts are expected. A more significant storm Wednesday/Thursday could cause several inches of snow and some freezing rain along with strong easterly winds, but the details are still being worked out on that front (pun intended).
- Winds: strong northeasterly “Fraser River Outflow” for the Northern Interior (Bellingham, San Juans, etc.) Sunday afternoon – Tuesday afternoon. Strong “East Winds” for the Portland metro area Wednesday
- Temps: upper 20s/low 30s Mon-Thu for Seattle. Upper 30s Mon, mid 30s Tue, Thu, near 30 Wed for Portland.
Current Conditions:
Moderate snowfall has been falling in the Cascades throughout the day in the wake of Friday night/Saturday morning’s system due to a process known as orographic enhancement, where moist air encounters terrain and rises, forming clouds and precipitation. However, yet another system is already bringing moderate rain to the Portland metro area/Washington Coast, and this precipitation will continue to spread inland tonight. The Cascades will see yet another increase in snowfall, with 1-2 feet expected through Sunday afternoon above 2,000′. This precipitation will taper from north to south Sunday afternoon, and the long-advertised arctic airmass will sink south in its wake.
Speaking of mountain snowfall – Snoqualmie Pass has seen 22 inches in the last 24 hours, giving them 92 inches total this season. That’s right – 25% of their entire season’s snowfall has fallen in the past day. Additionally, as of 7:23 PM Pacific time, all major mountain passes are open, which is astonishing given the amount of fresh snow we’ve seen since Friday.
The current webcam image from the top of Armstrong Express at Alpental (4,400 ft) says it all. You know what they say… a skier’s favorite webcam is the one you can’t see anything out of!
Sunday night/Monday morning: Snow for Western WA
After Sunday’s system moves into Eastern Washington, much colder and drier air will fill in behind it. This is one of the things that makes Pacific Northwest snow so difficult to come by – our truly cold air is also very dry and it’s tough to get precipitation and sub-freezing temperatures at the same time. As the temperature time-series below shows, Seattle will cool off dramatically between 00Z 1/13 (4pm Sunday 1/12) as this front comes through, with highs failing to reach freezing Monday and lows bottoming out in the low 20s by morning. Portland will be much warmer Monday with highs near 40… the real cold there won’t come until Wednesday when strong easterlies blow through the Gorge.
As far as snow goes, we should see a general band of snow drift from north-to-south as this arctic front moves south, and a convergence zone should increase snow for the usual spots in Northern King/Southern Snohomish County. Note the wide range in possible accumulations with the NWS forecast below… most locations will see very little, while others in the Puget Sound Convergence Zone could see 6″ or more.
This kind of local variability is extraordinarily difficult to communicate. Since TV meteorologists only have 2 minutes to cover their entire viewing area, it’s very difficult for them to point out these local differences. This is one of the reasons that “hyper-local” weather pages (such as WeatherTogether bloggers Brie Hawkins‘ Little Bear Creek Weather and Mark Ingalls‘ Tri-Cities Weather Facebook Pages) are so important. WeatherTogether was founded on this very mission – to create a community of hyper-local weather blogs that combine the benefits of the local focus and outreach of these hyper-local blogs with the collaboration and community of a worldwide network. We’ve got 8 states and two continents so far and are always looking for more, so if you think you have what it takes, send me an email at charlie@weathertogether.net and I’ll give you some more info!
The rest of Monday will be dry for Washington while Oregon will see showers, but Portland should stay warm enough to keep snow levels off the valley floor. I can’t rule out some wet, sticking snow Monday night into Tuesday there, but with temperatures still slated to rise above freezing Tuesday, impacts should be far less than any snow that could fall over Washington. Portland’s main action will occur on Wednesday/Thursday, and because it’s nearly midnight here, that will have to wait for another blog. 😉
