Arctic Blast Next Week

11pm Thursday…

Models are in very good agreement now that we’re about to experience our first “arctic blast” across the Pacific Northwest in 3 years.  It arrives Sunday night on northerly winds pushing out of Canada and continues the entire rest of the work week.  After Monday we go into a gusty east wind pattern with bitterly cold air moving through the Columbia River Gorge and into the Portland metro area.  Those waterfalls are going to be looking great by midweek all frozen up!

First, will we get snow Saturday night or early New Year’s morning?  I think anything other than flurries or a dusting is quite unlikely.  The showers are pretty much gone by the time the snow level lowers down into the lowlands.  In fact after 7am Sunday we’ll probably be dry.  Take a look at 5 different model forecast of precipitation after 4am Sunday, then the snow that could produce.  Yeah, looks pretty dry:


The ECMWF and WRF-GFS model snowfall forecast don’t inspire much confidence for sledding in the lowlands Sunday either.  Click for a closer view:

After Sunday that cold air takes over and we’re likely going to be sunny and dry most or all of the work week.  Take a look at the WRF-GFS cross-section:


Time goes from RIGHT to LEFT.  The right side is Monday morning, left side is next Friday morning.  Clear areas are less than 70% relative humidity…that’s a very dry atmosphere.  The wind barbs are easterly the entire time.  Through Wednesday morning the northeast/east flow extends all the way up to 10,000′.  This is a rare “deep” arctic airmass.  That means unusually cold temps in the mountains too.  Probably only 0-8 degrees at the ski areas Monday!  Northeast wind will be widespread across the region Monday/Tuesday.  After Wednesday it becomes more of an east wind through the Gorge but light wind elsewhere.  That calm wind will allow for very cold nights…5-15 degrees west of the Cascades.

Beyond our 7 day forecast there are hints of moisture returning next Friday, or Saturday, or Sunday, depending on which run of which model you are looking at.  This is the graphic I used for the 12 Day Trend I used this evening at 10pm.  I do this most nights to give viewers a GENERAL idea of what we’re seeing beyond the next 7 days.  It’s very useful in situations like this.  I think there’s a decent chance of getting some sort of snow west of the Cascades between days 8-12.  But it’s unknown at this point if we have a major ice/snow event coming sometime NEXT weekend or beyond.


The cool pattern is going to continue.!

It’s my weekend the next two days but I’ll be back at Sunday.

Have a safe and Happy New Year!

Chief Meteorologist Mark Nelsen

84 Responses to Arctic Blast Next Week

  1. Sapo says:

    Models have been all over the place since last night…Must have been some new data that caused them to overhaul our arctic blast, just when we though we were getting some consensus.

    Anyway, 850 temps don’t appear that they will be as cold as originally though, at least not right over PDX. we’re talking more -10c than the -14/15c that was being shown a day or two ago. No big change there…Latest GFS and WRF runs have indicated some insane east winds Tuesday/Wednesday, and with very cold air eastside our high temps won’t be any different because of the warmer 850s over us, so the short-term forecast remains largely unchanged.

    Precipitation is where the models really go haywire. A low approaching from the NW is still a distinct possibility Jan 6 or 7, but 00z Euro and today’s GFS runs have indicated a low from the SW as early as Wednesday/Thursday is now a possibility. Really no consensus on precip, gonna have to wait awhile for that. Bottom line though, it’s gonna be cold!

    • Garron 1/3 of a mile from Hillsboro Airport says:

      Yea! A WWA has been issued for the potential for no snow, or up to a flurry! Might as well cancel school for the next

  2. Well, that ended up being an interesting late-night bike ride, returning from a party on a night with a low forecast in the mid 30s, only to find it 30 with widespread freezing fog coating the roads. Took it slow and thankfully no wipe-outs.

  3. Mountain Man says:

    Let me point out, the Gem is in complete consensus with the 00z Ecmwf tonight for big snow potential next weekend days 6-10. Identical twins. Let’s just ignore the GFS when it flops around for now.

  4. Jason Hougak says:

    Running the 00Z ECMWF on the loop it shows a nice low push out of the Yukon out over the BC coast and slide south. I remember a similar situation in 93 I believe where the low did the same thing and stalled just south of Astoria. This caused the east wind to howl and the storm dropped 18″ of snow at our house in Boring. This could happen… we will see.

    • Mountain Man says:

      Yeah day 7-10 look good for wet snow. Arctic air swing over the water and back in over us. The cold air over the water will create bands of showers. It’s been showing that to different degrees for a few days and the gfs too in some runs. Not bad. Onshore not bitter cold but… Definitely snowy!

    • Jake-(Gresham) says:

      If I see a system is under 950mb doing that for Jan. 7 – 9 I don’t know what I’ll do. That’s exceptionally rare. You guys are the optimists. It’s established. I will go back into my lair now and keep silence. Lol!

    • Jake-(Gresham) says:

      Like there’s no way we get a 925mb stalling over Astoria. If that happens I’ll eat my hat. You heard it here first folks.

      PS: I don’t have a hate tehehe!

    • Mountain Man says:

      Jason, I hear you! Deep into the western gorge at 1200 ft and it’s not enough, but too much for the wife as compromise goes.
      Jake, looking at models, it looks good for snow this weekend… Maybe a lot, maybe a little. This is an unusual pattern where a low to the north would be snowy… Over-water trajectory is what we called it in the old days. Cold Air swinging over the water just long enough to pick up bands of precipitation without warming to much. 3/4 Ecmwf and about 50% of the gfs runs the last “2 days” show this classic snow setup happening. Give it time.

    • Mountain Man says:

      There you go! Something is going to happen this weekend and I’m not just saying that because Jim Little is my uncle lol.

    • Mountain Man says:

      I’m thinking a big wet snowstorm next weekend 75% chance!

  5. Jason Hougak says:

    00Z ECMWF sure looks like a low pressure sliding down the BC coast toward end of the run. Looks very promising to me!!!

  6. Jason Hougak says:

    Jake I most likely want snow more than most which is why I moved to the foothills. I’d of loved to live in a more snow prone area but my wife’s family and work has kept me here. These models are pretty good but anything can develope that the models can miss. Keep your hopes up. NWS posted winter weather advisory for both the Cascades and Cascade Foothills so I’m pretty excited. 3-6″ would be sweet before the long arctic plunge. I’m going to Maui in a couple weeks so I guarantee I’ll miss the big winter weather event!!! 🙄.

    • Jake-(Gresham) says:

      Thanks for the kind words but I think it’s time I moved to Bend or something. Lol! Yeah no I hear you though.

      Happy New Year. 🙂

  7. Jake-(Gresham) says:

    Using the Euro for weather system assessment.

    It appears our curse of lack of moisture continues. This is the system over Vancouver Island. Again like the system this weekend
    it’s put too far inland and is too weak for any signification snowfall (both barely strengthen over Puget Sound which is to be expected – not the Great Lakes).

    Next slide:

    I hate to call it, but right now I’m not seeing this arctic blast yielding
    any exciting snow event. Bahumbug to the New Year I say!

    • Mountain Man says:

      OK let’s take February 2013. Three days out, no storm in sight. Two days out, a hint of something. One day out, we’re going to get a snowstorm… During the one storm predicated, hey we’re going to get another snowstorm. Two storms and widespread 7-10 inches across the metro area. It happens a lot like that around here… 2004… There were bad runs in Dec 08… They are not perfect models, so average the last two days, then expect you might still be surprised one way or the other.

    • Jake-(Gresham) says:

      So you agree with me the agreement is not only lame but It sucks. 😛

  8. Jake-(Gresham) says:

    Looking at the long range models:

    It looks like the arctic air may be challenged around Tuesday where the largely Westerly flow:

    Is then faced with a change toward the Southern direction as a system comes in at an angle we don’t want at least here in the PDX area (South to North). This is how the arctic air largely gets taken away here in the valley during the dead of Winter:

    However, come Thursday it appears another high pressure wants to come in from British Columbia and cause a recursion event of arctic air:

    As of now, the biggest issue I see as others have clearly stated is the lack of moisture. In short, largest variable being precipitation potential. I don’t see any large snowstorm even into next weekend.

    We are heading into what appears to be a dry but very cold pattern. 00z Euro run almost finished.

    • Mountain Man says:

      I would recommend, don’t get to down on one run of one model, especially looking past the weekend and being the gfs. Struggle with consistent solutions will continue… Ecmwf almost done…

    • Jake-(Gresham) says:

      Have you had a chance to look at the models? It’s my day off and so far run after run has been pretty consistent. I know you’re pretty solid on this blog.

      I just am pointing out that the trend is staying butt cold and annoyingly dry. This train seems pretty set on such a destination. Just say’n.

  9. W7ENK says:

    Ive been watching this passively for a few days now. I don’t think this “event” is going to live up to the hype. A dusting of snow this Sunday — if we’re lucky — then the whole pattern shifts East. We moderate out to 37 degree rain, and it’s all over before next weekend. I’ve been saying this for three days now (elsewhere), and I see no practical reason to believe otherwise. We’ve been through this before, and we always pretend like we’re surprised when our weather wet dreams don’t come to fruition. Truth is, we all saw it coming, but y’all chose to ignore the writing on the wall.

    • boydo3 N Albany says:

      Well…we DO live in the Pacific maritime northwest after all.

    • Chris s says:

      0z gfs was sure a swift kick in the reality department!!!! Yikes… almost as epic as January 2011 in terms of falling apart so fast…. sad, but most likely the outcome. This one will sting for a while for quite a few model run weenies!!!!

    • Runtmc says:

      Thank god you’re here (and elsewhere) to provide the wisdom and experience that we all lack. Shame on us for indulging in some weather fantasies from time to time when the models give the siren’s call. It’s good to have W7, the old blog sage, back to keep us in check, “forecasting”a mild winter event in the PNW lowlands. A true soothsayer.

    • GTS1K' says:

      It’s reverse wishcasting psychology!

      May it work, W7, The dome has proven vulnerable once already….

    • Sapo says:

      W7 actually the whole pattern has shifted west on most of these runs…trough way over the ocean on today’s 12z Euro which isn’t good for us. If anything I’d like to see an eastward shift on these runs

      Time will tell!

    • Sapo says:

      models are clueless past day 3/4, no agreement

  10. Jake-(Gresham) says:

    Now that the arctic air is set to arrive and is no longer a variable that moisture in la-la-land looks to bring quite interesting potentials if it does come to fruition.

    What I like is that it’s the dead of Winter. This air will not moderate and so now it’s all about system trajectories from here on out (i.e. no weather system gives us a South wind)? We could be socked into a cold pattern for quite some time. I’d argue we’ve been progressing into it dare I say it? What a normal Winter should look like here!

    A recursion of cold arctic air also looks to want to occur on Monday the 9th of January. If that happens it’ll be the coldest Winter I’ve ever witnessed. I think most millennials will think the sky is falling if that happens, lol! I was born and raised in PDX so I remember 94′,95′, 2004, 2008, and whatnot but this is my first recollection of seeing the potential of a general Winter that was cold throughout.

    I remember as a kid going to museums around PDX and seeing all the pictures of the settler times with log cabins banked on the sides with snow and wagons making ruts in the snowy roads. Every since I got into weather I’ve wanted a ‘real’ Winter here.

    Looks like this Winter may give us if not a taste of that or maybe more – who knows. I’ll take it.

    I really need to move to Montana.

    • Ash Qelon says:

      Two weeks ago this news source was actually rather impressive accurate in forecast-timing snow and locale’ it went and occurred.
      It crept in as they said , I got caught in the first 30 minutes of it , barley escaped and got home in same time as regular day.
      So, again, I feel this source is respectively credible to look at. Maybe not on 3-4 days out like this yet, 24 hours and the same day forecast is as they say 95% of the scenario.
      The weather they showed changes and is a bit rogue, and they followed it 2 weeks a go with continual updates, I say was very good.

    • Jake-(Gresham) says:

      Alan, I work / study in the scientific community. Spelling is not my strong suit. Not an indication of my time spent at the desk. I think you should be more concerned that you’re following my posts and saying the same thing over and over again. Might want to look into that behavior.

    • Jake-(Gresham) says:

      “One thorn of experience is worth a whole wilderness of warning.” – James Russell Lowell

  11. Jake-(Gresham) says:

    New Year’s Eve Snow for the Puget Sound Lowlands? (Friday, December 30, 2016):

  12. flurball says:

    Had not noticed the “fun, weird, hate emails” tab on the blog until now. You know it’s a slow weather week when rectal thermometers come in to the conversation. Probably not so much this next week. Stay 98.6 my friends.

  13. WEATHERDAN says:

    Looks like 68-69 redux to me. Both Winters are very similar so far. However for you sun lovers take heart. We had an early warm Spring and a nice warm Summer in 1969. Peace and a Happy New Year. Bring on the snow and cold.

  14. What USDA plant hardiness zone is Timberline Lodge in??? I know PDX winter mins are near 20F, which is the zone 8-9 boundary. DLS is on the border of zones 7 & 8.

    • GTS1K' says:

      Well, if the average winter lows are in the -5 to -10 range then 6a, -10 to -15 is 5b and -15 to -20 is 5a.

  15. A big lowland snow event is still very much in doubt, but the cold seems to be a lock, at least for the coming week, and quite possibly longer. I’m looking forward to seeing the island’s largest lake freeze over for the first time in about four years. (Less dramatic than it might sound, as it’s shallow and thus cools off fairly rapidly.)

    • Jake-(Gresham) says:

      Yeah looking at the last run of the long range models we have no chance of getting out of this cold till at least January 9th. Even there, the indications are that we will have a ton of cold air sitting just North of us in British Columbia around the Washington State border.

      The possibility of a recursion of another arctic blast coming down is something the models are starting to show. However, the
      data is packed right now for the first week as others have mentioned for the first week of January. I’m not even looking at that!

  16. Sapo says:

    Both the ECMWF and the GFS are coming into agreement about snow chances…Granted it’s all 7-8 days out but it’s nice to see some trends. 12z GFS gives us 6-7″ with that low from the NW on Friday/Saturday, ECWMF is about 3-4″ (but euro in total gives us like 15″ as a low from the southwest approaches around day 9). Ensembles look very snowy too. I think it’s likely we see a snow event of some kind late next week/next weekend, real question is how big.

    Sunday is looking just a tiny bit snowier with each run, more over water trajectory and the trough a bit more westward, more qpf for us and possibly more snow. Could be some snow showers Sunday evening too. We’ll see.

    Next 10 days will be fun

    • Sapo says:

      when i say fri/sat I’m talking about the 6/7 but when i say sunday I’m talking about new years day fyi

    • Sapo says:

      Wow I’ve never seen anything like the ECMWF ensembles today…Mean is 1 foot of snow by the end of the run, 90% of the members show 6 inches or more. Good consensus on a low pressure forming near van island next thurs/friday. Most of this snow comes in Jan 5-10 period. Most members show 2 snow storms, one around the 6/7 and one around jan 9/10. Will be interesting to see what happens.

    • Mountain Man says:

      Sapo, what do you use for Ecmwf ensembles? What I mean is… Do you pay or do you have a link you can post? With all the model maps and data available for free, the one thing I’ve never found is Euro ensemble charts that you don’t have to subscribe for. Any link would be appreciated.

    • gidrons says:

      There’s a lot of maps posted at the weatherforums if you can tolerate the inane banter.

    • anon says:

      Sapo you rock buddy. Love the thorough updates.

  17. Roland Derksen says:

    This will be actually our second “arctic blast” of the winter here, so the novelty of it is somewhat diminished for me. However, maybe it will be a colder, deeper one than the one we had 2 weeks before. This might end up being my coldest winter since 1992-93.

  18. LongtimeLurker says:

    Back to college question for my daughter. Leave on Saturday to go back to Seattle before the moisture hits or wait till Monday as planned. Mark, what do you advise?

    • Jake-(Gresham) says:


      “So the bottom line in all this is that you should expect increasing clouds on Saturday as the trough approaches. Light rain will begin over the lowlands around dinner time and then transition to snow showers between 10 PM Saturday and 1 AM on Sunday. A few hours of light snow will follow before the atmosphere dries out on Sunday in the cold air. Much of the lowland snow will be focused on a Puget Sound Convergence Zone over north Seattle and the arctic front–the zone of transition to the cold, continental air. Most of the region will end up with little to perhaps an inch of snow. Not a big event, unless our forecasts are way off.*

  19. GTS1K' says:

    So, with lows in the teens and East wind, should I mulch my already 3″ tall garlic?

    • jeloughrey says:

      Definitely. Pile on several inches of leaves or straw. Also protect bulbs or anything else in pots. I bank my pots up against the house, throw leaves over the top and secure with a sheet of plastic. Everything came through surprisingly well the last time we had such a prolonged deep cold spell. I may even move some plants from my unheated greenhouse into the house tomorrow. Better to be safe than sorry.

  20. GTS1K' says:

    Astute snark, Mr. Sunshine…

  21. JJ78259 says:

    Viewing the blog over the last 3 years there has been quite a few “winters of 50s and 60s are gone” well how things have regressed. It is amazing how few comments surrounding the large El Niño set up that really affected the last three years of Northwest Weather. Mark’s comments about the warm weather was a fluke enjoy it maybe another 20 years for this to happen again is truely ringing true! Reliving winters gone by will rekindle some great memories!

    Happy New Year!

    • It’s hardly certain this is going to be a repeat of, say, 1950. To assert so at this stage is wishcasting. Right now, the optimistic scenario (for winter-lovers) would be a repeat of 2008, and even that’s uncertain at this point. The necessary moisture for a big snow is far from certain, and will not be happening at the start of the event, which will see a dusting at most. The models have all basically agreed on that latter point, and for some time now.

      Yes, there are hints the coming event could be abnormally long-lasting, but there were hints early on that last month’s cold spell might last until about now. It didn’t. At this stage we’re really in wait-and-see mode to see if it will end up being an epic winter or merely a cold one with no big lowland snows.

  22. David Wheatley says:

    Thanks for the update, on a positive note it will surely look better next time!!! .

  23. Anonymous says:

    hey, maybe this arctic blast will kill the box elder bugs and the stink bugs!!!!!

  24. JERAT416 says:

    Thanks for the update Mark! Still no cold snap of ’89 though, when I could walk on most ponds and slow moving streams.

  25. runrain says:

    An unbelievable 77 deg here in Phoenix yesterday. I went hiking in the Phoenix Mountains area and worked up quite a sweat. AC was on full in the car afterwards. Today will be a more manageable 71 but still tshirt and shorts weather. Turns colder next week with highs in the upper 50’s.

  26. Here’s a question for you all. If you could see one and only of these three events in your lifetime, which would it be?

    -Break the all-time low at PDX by a wide margin (-6 to -10 F temps)
    -Break the all-time high at PDX by a wide margin (110 F+)
    -Tie both the all-time highs and lows (-3 F and 107 F)

    • Jake-(Gresham) says:

      Break the all-time low at PDX by a wide margin (-6 to -10 F temps).

      The homeless would be in shelters because that would be a long term event and everyone else would enjoy it too. Hot temperatures are not good because not everyone has AC, just my logic. 😛

    • muxpux (Longview) says:

      I like this question.

      I’d have to go with the all time low. When it gets to 107 or 110, there isn’t much room after that, and I love hot weather but anything above 100 doesn’t really feel much different.

      I’ve never been in sub zero temps, but I can tell you that 5 degrees FEELS a lot different than 25

    • Paul D says:

      Break the low! I HATE heat waves.

    • GTS1K' says:

      Customers?!? You’re telling me people pay for his snark?

    • Mark says:

      Playing tennis – outside tennis – during the all-time high.

    • GTS1K' says:

      I’ll take door #3

    • Garron 1/3 of a mile from Hillsboro Airport says:

      Technically speaking, before there were airports to take reading from, Fort Vancouver the Army recorded 3 days in a row, and 4 for the month of January 1862 below zero. One of those days, it was -10!
      It would be fun if it got that cold again, just because you can take a broiling hot cup of water, toss it into the air, and it turns to snow! When it’s 110+, you can throw a cold cup of water in the air and it turns into sweat!

    • Anonymous says:

      Break the all time high. Pipes do not freeze in the summer.

    • Jake-(Gresham) says:

      Garron, thanks for posting that information; I had no idea on that. Really interesting stuff!

  27. Diana F. says:

    Mark thanks for the recent posts, it’s been great having you back—I like to do some follow-up studying whenever I read one of your lengthier, more technical posts, ….and you’ve given me LOTS of things to research, always appreciated : )

    Well, a nice Arctic Blast does sound exciting! I keep thinking that the cold will meet the moisture at some point in January, and bring us a the real thing, not just snizzle. Feeling hopeful but trying to remain calm.

    If nothing else, I can keep our beverages in the garage where it’s colder than the fridge!

    As long as I can’t store the ice cream in the garage I think we’ll be ok. Plan on getting some good use from a recent splurge—a down comforter. Time to say buh bye to the 25 year old version. Sheesh where does the time go? I dunno but that’s a lotta time spent waiting for snow!

    Here’s wishing #MyFellowGeeks a Safe and Happy New Year Holiday!

    (Personally I’ll be in front of a fire, drinking sparkling cider and eating popcorn and cinnabons, binge watching the History Channel’s “Vikings” A-L-L weekend, yah baby! Merry Christmas to ME!)

    • Matt (Vancouver 98683 @150ft) says:

      I love your fervor, Diana! =)

      Thanks, (as always) Mark! I promise to put the covers on my outside water faucets.

    • Garron 1/3 of a mile from Hillsboro Airport says:

      Yep, I love your enthusiasm as well Diana! I have been hooked on meteorology since I was 4 or 5 years old. ( A massive thunder storm my mom woke me up to watch I think did it) Always fascinated by mother nature. I am always learning new cool stuff on here as well as the Facebook groups, and have the same issue….Must go look up this stat or that reference! Too much fun. HAPPY NEW YEAR TO YOU TOO! AND MAY IT BE A SNOWY ONE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  28. Eugene Dave says:

    Blech! A layer of snow insulation typically helps the sensitive vegetation survive these conditions better.

    It is also an incredible disappointment to see such a massive arctic invasion come without precip. Dammit!

  29. Chris says:

    A few days ago you mentioned that places like Sandy, Estacada, and Mill City may be in for a few inches of snow from the moisture on Saturday and Sunday. Do you still think that will happen, or is there just not enough moisture with this?

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