Sunday Morning: First Snow Sighting Of Winter For Many of Us

6pm Thursday…

If you haven’t left the lowlands this winter, most likely you also haven’t seen a single snowflake. February is less than 10 days away! That’s unusual in our climate. Typically we have a close call or two, if not real sticking snow, by this point in the winter. Not this year, it’s been very mild. But if you are up before 10am Sunday, it appears there’s a decent chance you will at least SEE snowflakes in the air. Sledding in the lowlands? Unlikely.

For the short attention span (TLDR) folks…

Winter Weather Highlights

  • Between 4-8am Sunday, precipitation arrives across NW Oregon and SW Washington. Most likely it’ll be a rain/snow mix in the lowest elevations (where most of us live)
  • There’s a decent chance it falls as mainly snow for at least a few hours 7am-10am, even in the lowest elevations. It could get very exciting weather-wise for a few hours!
  • Temperatures remain ABOVE freezing Saturday night and Sunday = little or no sticking. If it falls heavily enough, it might briefly accumulate on cars/barkdust etc…
  • IF you live up around 1,000′ and above, there’s a better chance your neighborhood turns totally white for a few hours.
  • IF you live around 1,500′ and above, expect 1-3″ Sunday morning through midday. There are no spots in the metro area that low.
  • Highways/roads will remain snow-free Sunday in the metro area, except at/above 1,000′ where they could briefly turn snow covered.

THIS SHOULD BE A “CONVERSATIONAL SNOW” EVENT FOR THE LOWEST ELEVATIONS. That means everyone will be talking about it; plus posting Instagram/Facebook pictures of their dog/cat/pig/chicken/duck running wildly about outside, but it won’t affect our lives otherwise.


TECHNICAL DETAILS

A cool upper-level trough (the first of several) is sliding down north to south along the West Coast. This system is headed for California and far enough offshore that we’re seeing almost no showers inland. A mainly dry and cool airmass settles over us Friday & Saturday. Drier air filtering in from Canada gives us LOTS of sunshine Saturday; enjoy that day after a cold start. We’re not getting a “cold blast of air” by any means, just a bit colder.

By Saturday night another cold upper-level trough is sliding south along the BC coastline. A cold front then moves inland midday Sunday. Here’s a loop from the ECMWF model showing the movement from 1am to 7pm Sunday. Not exactly a “storm” eh? All models have been showing this scenario for several days and all agree on the timing; pretty good for 3-5 days ahead of time.

Freezing levels Sunday morning will be up around 2,000′ or so with this system, which typically means we might see snowflakes down to maybe 1,000′ and just a rainy Sunday morning in the lowlands. But a few things are different Sunday morning which should bring those flakes lower:

  1. Overnight cooling, while minimal, means this system comes in at the coldest time of day
  2. No significant “warming” onshore wind. There’s no cold/dry wind blowing out of the Gorge, but there’s no push of warmer air before 10am either. It should be mainly calm Sunday morning, at least for a few hours.
  3. There are signs we get a burst of heavier precipitation between 7-10am. Heavier precip = better chance for flakes to survive a longer fall through the atmosphere

These all point to a setup where snowflakes may survive falling all the way down to the valley floors west of the Cascades (less likely along the coastline) for a few hours Sunday morning. The reliable WRF-GFS model from UW shows the above freezing temps through Saturday night. At 4am it’s in the mid-upper 30s in Portland. This isn’t a setup where precipitation arrives at sunrise after a frozen night.

But as precipitation starts falling, look how surface temp drops to 33-36 degree range

Then 10am

That’s pretty much a snow sounding; at/below freezing except for the lowest 500′ or so. By 1pm Sunday, the cold front has passed, mixing (warming) the lowest layer of the atmosphere with a southwest or westerly wind. At that point we’ll just see rain or mixed rain/snow showers. It appears we have .25 to .50″ precipitation to work with, enough for 1-3″ in higher elevations where this falls as snow and sticks.

Models ALWAYS struggle with predicting snow totals in these marginal events. This morning’s ECMWF model continues the “little or no sticking snow” idea; you need to be up/above 1,000′ (or 1,500′) to make a snowman this time around

Note the coarse resolution here. I’ve purposely left it “unsmoothed” so you can see the model resolution. It doesn’t see the West Hills or Chehalem Mtn. at this 9 kilometer resolution. It also doesn’t “see” the Columbia River gap between Woodland and Longview, thus painting a bunch of snow for Kalama, Rainier, Longview, & St. Helens. It “thinks” the hills of Columbia county OR just merge into the hills above Kalama & Woodland. Higher resolution models (4km & lower) DO show those features, but we don’t have those today. They run just 72 hours out in time and only cover to 4am Sunday.

Alright, so that’s your first “big snow chance” for this season. That was a joke, it’s not a big snow chance. We MIGHT be close again early next week (either Monday morning or Tuesday night), but we can discuss later.

I still want to be clear that this is the not the beginning of a cold/snowy weather pattern. Sure, we’ll be getting more regular frost and overnight freezing. But no sign of an arctic blast through at least the first few days of February.

I probably won’t post tomorrow considering how minor this event will be; time to get out and enjoy the wintry outdoors. I’ll definitely be back with an update Saturday.

Chief Meteorologist Mark Nelsen

46 Responses to Sunday Morning: First Snow Sighting Of Winter For Many of Us

  1. runrain says:

    How many of us are going to be waking up tonight every hour just for the chance to see a snowflake in the street light? (*raises hand)

    • JohnD says:

      Maybe. 37.2’ currently here in inner SWPDX @ 200’. If the doggone SW wind stays at bey then we might have a shot. Not holding my breath. Have to say that the big picture upstream holds a lot of intrigue too! Our winter has arrived!

  2. Mountain Man says:

    So… After a hitting 23 this morning, the sun gave me a high of 37, already down to 33 as the daylight fades, I’m feeling pretty good that whatever falls tomorrow will be mainly snow tomorrow morning here in my foothills location.

  3. tim says:

    The cfs model keeps going back and forth from la Nina thru rest of this year or el nino by this fall ever couple of runs wonder why it’s struggling so much lately?.

  4. runrain says:

    Wow. The Sierra could see several FEET of snow mid week next week. Interesting to watch.

  5. Roland Derksen says:

    To me, this current weather pattern (of rain/snow mix and coolish temperatures) is finally what we should expect of a La Nina winter.

  6. Chad says:

    Really cold air that had potential for looking like it will be pushed east and northeast.

    At this point just give us spring already.

  7. JohnD says:

    Alaska soon to be in the deep freeze! Finally! Soooo hoping for a SE migration of some of that!

  8. lurkingsince’14 says:

    Heading up to Welches area for a few days, hopefully the forecast pans out but it seems kinda marginal for temps even at 1300ft… 🙏🏻

  9. Andrew says:

    Models fairly stable over past 24 hours. Both EURO and GFS indicate a slightly better chance for sticking snow in the Tues-Wed window. But it’s largely a repeat of tomorrow, just with slightly colder temps. Unfortunately this isn’t the true “setup” for sea level snow so conversational at best, nada at worst. Hopefully this pattern will give us a real shot at the colder air in the near future.

  10. Jason Hougak says:

    Winter Weather Advisory above 1,000’, we’ll see what happens.

    • runrain says:

      Keep us apprised. We live vicariously through your reports up there in the foothills!

    • Mountain Man says:

      The next 10 days are looking pretty good for the foothills, I’m pretty sure I’ll have several inches but scattered a little bit at a time.

  11. Andy says:

    At 7:15 am in Albany 25 deg…maybe one of the coldest temps this winter.

  12. Source regions for real cold air have been virtually non-existent this season so far

  13. Zach says:

    Can’t really complain about this new weather pattern. Wet like we had in December / early January, but colder. Looking like good mountain snow totals all across the west in the coming weeks, especially California / SW where the drought situation is really bad.

    • JohnD says:

      Agreed. And really thinking that upstream has a lot of promise. February has shown to be very impactful in recent years. Perhaps this year too!

  14. Roland Derksen says:

    Well, I’m feeling a bit let down by the latest forecast here- calling for either snow OR rain- for the next few days. Perhaps I should stop listening: just let nature take its course!

  15. JohnD says:

    Nice little snow event in Bend-Redmond today! Lucky them!❄️

  16. 5OClockCharlie says:

    Cliff Mass once again calling for more snow (1-3) below 500′ in the metro area and even more on Tuesday. My money is on Mark of course, but will be interesting to see what actually happens! I’m wondering if Cliff is intending to mean an equivalent of 1-3in of snow will fall (but not stick) since Mark is calling for the same above 1500′. Either way this is at least SOMETHING (albeit small) to get excited about this season.

    • Andrew says:

      My personal theory on this is that Cliff often relays a more literal interpretation of the models, where Mark is much more inclined to point out where models tend to err. Mark certainly relies on models and uses them liberally on this blog, but he also talks about how they trend and isn’t as prone to taking a single run at face value. They are both phenomenal forecasters and I love hearing the different analyses. Cant be overlooked that the difference between 1-3 inches and just snow in air can literally be defined by a degree or two. These forecasts are highly nuanced. Under this type of setup, for every surprise three inch snow event I’d say we get at least five that involve mixed precip and no sticking. My money is definitely on that outcome playing out this time.

    • Chad says:

      Mass is a quack like Parsons.

  17. Andrew says:

    I’m disappointed the models are reverting back to a milder pattern towards the end of next week and beyond. There were some indications a few days ago of a nice arctic air build up around us. That has all but disappeared. Hopefully just the standard ebbs and flows of model runs. I’m still hopeful the next few weeks will bring us more opportunities for real snow but can’t say models support that right now.

    • Joshua Lake Oswego says:

      Next week is also looking bone dry now. Previously, it looked like we had some systems coming in every couple of days. Now, after Sunday’s .30” of rain, we’re high and dry through the end of the week. Meanwhile, the entire state of California will get hosed.

    • Zach says:

      I wouldn’t get hung up on what the GFS says more than 10 days out. They are all really volatile due to the SSW.

      • Joshua Lake Oswego says:

        Maybe it’s just my perception, and surely anecdotal, but the GFS seems to be beating the pants off of the ECMWF lately. The Euro is seemingly always too optimistic with cold and precipitation, only to fall back in line with the GFS within a few days of the “event”.

        • Andrew says:

          That has certainly been case with this “event.” EURO had 850mb temps at -8 or -9 earlier in week and now conforms with GFS more at -5 range. I anticipated this would happen given general weather pattern we’re in. Interestingly, EURO also as the 850mb bottoming out in the Tuesday timeframe more so than Sunday where the GFS is a little colder. So if we can muster enough precip i think chances of more significant – albeit still conversational – snow could be higher Tuesday morning than Sunday. Mark and Cliff both allude to this so not pretending this is somehow breaking news. Mark understandably is focusing on Sunday given proximity and weekend implications.

    • JohnD says:

      Looks like Alaska will be “finally” getting significantly colder in the extended. A good sign, perhaps, eventually for us.

  18. tim says:

    I see the cfs and cansips model wants to keep la Nina going thru the summer while other like jamstec and bom are leaning towards el nino, I’m curious to know which ones are right, of course our summer temps aren’t dictated by enso.

  19. Tanis Leach says:

    WRF GFS 4km goes out to 84 hours. I mentioned what it said on the last post. Otherwise great write up. Appreciate it.

  20. Paul D says:

    Oh snap! I better get to the grocery store and empty the shelves into my cart!

  21. W7ENK says:

    Thanks for the post, Mark.
    Good write-up.

  22. Mountain Man says:

    Thank you Mark Nelsen, it is appreciated! 👍

  23. MasterNate says:

    Pete Parsons 3 month outlook was out today and calls for below average temps and near normal to slightly above normal precipitation. La Nina late means colder late winter and early spring. It appears we are now transitioning to that for what its worth.

  24. Anonymous says:

    Maybe if this was just before Christmas it would excite me with the holiday music ect but in Feb I need a proper storm to make me happy lol maybe this is a warm up to the real storm mid Feb

    • Jim says:

      Ok February doesn’t start for 10 DAYS!

      • Anonymous says:

        Technically 8 days from our first snow expected which is Sunday I do realize its still January but with only 8 days left and forecast already predicted into Feb this Month feels pretty much done with key word feels

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