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It’s Super Bowl Sunday, but Mother Nature may be saving this year’s “Super Bowl of winter weather” for the day after.
Some snow is already falling in the South Sound, with a half inch reported in Enumclaw and 1″ in Grand Mound. This is just the appetizer; more is on the way.
All indications are converging to a significant snow storm across much of Western Washington, with potential to snarl the Monday morning and perhaps evening commute as well. A Winter Weather Advisory is in effect for all of Western Washington.
Important caveat: Temperatures are expected to be just barely cold enough for snow, so there is potential for much less snow or even no snow and just a rainy day if temperatures are off by a couple of degrees. This is a less likely scenario, but it is possible. The snow is by no means a slam dunk, but the odds are considerably in its favor.
We’re watching a very cold area of low pressure swirling offshore that will move closer to our coast Sunday, then push across the region Sunday night into Monday, increasing shower activity. In the meantime, a strong push of arctic air from southern B.C. is expected to bring colder air in from the Fraser River Valley later Sunday into Monday and drop temperatures to near freezing across Western Washington.
The Leading Scenario at this Point: Snow levels will gradually fall during the day Sunday from around 1,000 feet to about 500 feet by the afternoon and evening. Rain will gradually turn to a mix and then wet snow, especially in Southwestern Washington and above 500 feet by the evening. Our rapid update hourly forecast model suggest about 1″ of snow above 500 feet and in Southwestern Washington by around 8 p.m. with 2-3 inches likely in those spots by midnight, while sea level locations may begin accumulating their snow.
Snow is likely to fall overnight across much of the region with at least 2-4 inches on the ground in most spots by Monday morning. Snow showers will continue through the day with additional accumulations reaching 3-6 inches by the end of the day. Light snow showers may continue Monday night into Tuesday and even Tuesday night, although snow levels will rise to a few hundred feet during the day Tuesday and may present just a mix or wet snow near sea level.
Range Of Possibilities: For most areas, 3-6 inches on the ground by Monday evening with some of that already there for the morning commute is about the average of several forecast models that are tracking the event. However, you should know that there are a number of models that are predicting even more snow — on the order of as much as 8-12″ in the Puget Sound region and Southwestern Washington. This is *not* the most likely scenario, but this is still a *possible* scenario so you should be thinking about what would happen if that scenario does come into play. And again, if the Fraser wind fizzles and we stay at 36-37 instead of 32-34, then this will be foothill snow and slushy lowland rain and we move on with our week. That is among the least likely scenarios, but its odds are not zero, so this *does* have a chance to fail.
To Recap:
Best odds: 3-6″
Lesser odds: 7-12″, 1-2″
Least odds: Rain, 12″+
Timing & Potential Impacts in Leading Scenario Case:
Sunday evening: Some wet snow on the higher hilltops and places above 500 feet, and in Southwestern Washington may have some slushy roads for returns from Super Bowl parties (although roads are starting fairly warm). This is likely a low impact.
Sunday night: Snow levels fall to sea level making late night travel possibly treacherous. Moderate impact. Strong northeast winds will blast Whatcom County and the San Juan Islands starting late Sunday night into Monday with gusts to 50-55 mph, making for blowing snow, very cold wind chills, and potential power outages.
Monday morning: Snow should be on the ground for the Monday morning commute, perhaps as much as 2-4 inches by then, even in the city. This could be a very high impact event. Schools may delay or close. Hills will be difficult to traverse. Fraser Wind continues to blow with gusts to 55 mph in Whatcom County.
Monday midday-afternoon: Snow showers continue with an additional 2-3 inches likely. Driving around the city may continue to face challenges.
Monday evening/night Snow showers taper with light accumulations. Storm totals should be around 4-6 inches by now. Evening commute may also face challenges.
A second wave of moisture may bring additional snow showers Tuesday and early Wednesday — especially during the evening/night/early mornings during lowest temperatures, but light, if any accumulations expected at this point.
Winter runs away in a hurry
Long range models suggest drying later Wednesday then a rapid warmup into the end of the week with a return to heavy rains and highs over 50 degrees.
Scott’s Forecast Notes: Could this be another October 15 deal?
So I have to admit Sunday feels a bit like October 14th, the day before the big windstorm that wasn’t. Here we are looking at all our tools that are steadfast in that Western Washington is about to be hit with a storm that could have a major impact on the region. In the aftermath of the “wind storm”, there was a lot of anger not in just the missed forecast, but that most people felt like we meteorologists didn’t convey any idea there was a chance the storm wouldn’t happen. To be honest, the odds that wind storm wouldn’t have happened were pretty darn low, and while that low chance managed to be the what occurred, the potential of that storm was pretty great. And a lot of us to this day feel like if presented with the same data, we would have made the same forecast.
But we want to be effective in our jobs, and to that end, local meteorologists have had several meetings since that ill fated breezy day. Our main takeaway was that we do need to do a better job in communicating the uncertainties of predicting the future, giving you not just a declared best chance forecast as gospel, but to lay out the odds of the range of possibilities to show that weather forecasting is never a slam dunk and to let you, the consumer, digest the storm predictions how you feel best.
We are working on better tools to present these odds in a clear and understandable way and working on mathematical tools to give the real calculated odds of each scenario. That’s not quite ready yet — we’re still in the works. But I hope at least in this forecast and the one’s you’re seeing now, there is a better highlighting of what *might* happen as opposed to what we just think *will* happen. There is a not-insignificant chance this snow event will bust, just like its windstorm predecessor. But there is a much higher chance it won’t, and especially around here, people need to know when there could be a widespread snow on the ground.
For those who live on hilltops or down a hill and sometimes preemptively park your car down/up the hill when snow is in the forecast, it’s a good idea to consider that strategy for Monday. For those heading out to stock up on Super Bowl food, maybe grab some extra staples just in case. If you’re car is nearing “E”, toss some fuel in it today. If you have friends or family with medical challenges or limited transportation options, make sure they’re stocked up on any prescriptions and have their own staples, or maybe go have them spend a night or two with you. For those who have kids in school, have a child care Plan B if schools are closed.
All of these don’t really hurt. You’re prepared for a few days of snow mayhem and if it rains instead, you’ve saved yourself a trip to the store or gas station later this week. For those who have events planned on Monday, you’ll know when you get up in the morning if the snow is on or has busted. If the call has to be made sooner than later, I’d err on the side of it’ll snow.
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