A New Year: Tough Forecasting Ahead!

9pm Sunday…

Who would have thought these 12 days of Christmas would be so challenging for forecasters?  Actually I suppose this is the busiest time of the year for meteorologists in the Pacific Northwest.  So lets just jump right into it.

The forecast for the metro area worked out just fine today, but the snow was heavier than expected up in Columbia County where several inches fell quite close to sea level.  Also we had a band of showers drop some heavy snow right over Clackamas and northern Marion counties this evening.  The official snow total in Portland?  Yes, once again it wasn’t measurable…just a trace at the NWS office.


But check out those totals in the hills around the metro area!


If you live up around 1,500′ you really scored…after two winters of very little foothill snow it’s nice to see it back.

Showers will continue off/on tonight, although in general the airmass is drying out as modified arctic air filters down into the Pacific Northwest.  That dry/colder air has made it through the Gorge and the east wind has started blowing in the usual spots.  Already gusting over 30 mph at Vista House.  The wind will blow until further notice…sorry!  Tonight’s low temps won’t be too cold assuming we don’t get much clearing.  Probably just below 30 here in Portland.  I raised the forecast highs and lows the next few days since it’s obvious models have overdone the amount of cold air to our north, plus too much wind at night will likely keep PDX from dropping much below 22 the next few nights.  Still, high temps will likely just creep a bit above freezing tomorrow (32-34 metro area) even with mostly sunny skies.  Colder air will continue moving south through the region and then through the Gorge the rest of the week, but it definitely won’t be any sort of mega arctic-blast.  Just 2-3 days ago the northern stream of the jet was expected to dominate until further notice.  Instead we’ve seen models gradually allow more and more energy from the southern stream of the jet (milder and moist Pacific air) to move north over us the rest of this week.

My 7 Day Forecast this evening is mainly based on the ECMWF and its ensembles keeping the California system Wednesday to our south; thus the dry forecast.

Wednesday is a real challenge.  Most models other than the ECMWF are pushing some sort of moisture up north over Western Oregon Wednesday.  That’s right over the top of the cold air.  If they are correct, snow is likely coming for at least parts of the Willamette Valley Wednesday.  Here’s the WRF-GFS precipitation forecast ending Thursday AM, classy…nice dry hole over PDX:



Beyond Wednesday, all models agree on a “transition event” this coming weekend as we get rid of the lingering cold airmass.  Most likely a snow to freezing rain to rain event.  The ECMWF earlier today looked very similar to January 2004 with a low pressure system brushing up against the coastline but never really moving north of our latitude.  That’s a sort of “meteorological drive-by”.  It doesn’t dislodge the cold air, cold east wind continues, but a bunch of moisture arrives over the cold air.  What the ECMWF shows is a typical metro snow/ice storm Saturday & Sunday.    The GFS gradually warms us up Thursday-Saturday and we’d probably see little/no snow next weekend.  The evening GEM is more like the ECMWF showing a snow or ice event next weekend.

Chief Meteorologist Mark Nelsen

62 Responses to A New Year: Tough Forecasting Ahead!

  1. Jake-(Gresham) says:

    So gone are the teens at night; with the exception of Friday according to Mark’s forecast.

    Also, the key thing of watching for the Euro to trend toward the GFS has not occurred. The opposite has been happening to the point it’s like cat see’s dog, cat hisses on dog, cat chases dog around around the park – taking the owner along. LoL!

    So while they’re not, “consolidating” things are going the wrong direction. Unless the Euro in the next run shows some food chain hierarchy level aggression. Yeah….

    We’re looking at the model runs at the weekend as more of an icy mess for the whole of PDX as Mark is easing the masses into.

    I’d rather have rain if that window is what we got. Shoot.

    • John Fairplay says:

      It’s pretty shocking how truly bad the tools are available to these forecasters. Somehow they always predict airflow that gets warmer and warmer and warmer as it approaches Oregon during the winter, no matter which direction it might be coming from. At some point, it would probably be wise for the Mets to just add 5-10 degrees to whatever the models predict 5-7 days out.

    • Sapo says:

      Too far out to predict exact precip type/duration/when do we moderate for this weekend. Things are certainly looking pretty dry for Wed and we’d need to see a full 180 with the models to get a snowstorm up here in PDX.

      This weekend it’s too early to say exactly what precip type is gonna be, but looking like more of an ice storm, probably starting as snow though. Plenty of time for things to trend more snowy and less icy, models have flipped around in shorter time frames

    • JohnD says:

      For those of we long time lowland Western Oregon (and similar terrain) winter weather fans, times like these can simply be hugely frustrating. How many times have we seen similar? I am not throwing in the towel yet; but what seemed so promising only a short while ago, now seems anything but….We’ll see what ends up materializing, but more often than not, dramatic model changes typically are not to our advantage.

    • JohnD says:

      B-t-w did enjoy an 8 mile, 3 hour loop hike today via the Tilikum and Sellwood Bridges–amid low to mid 30’s temps, overcast skies and even a few snow flurries!

    • Jake-(Gresham) says:

      Nice hike JohnD. Yea me and a few cousins went up into the gorge a few weeks ago. The waterfalls are beautiful; roaring right now. Really is worth getting out now and then in the Winter for sure.

      Sapo, I’m with you guys on all points. Not giving up and I’m of the consensus that a 3 – 4 day forecast is the reality of the, “long range models.” In my humble opinion, a 7 day forecast is just there to give the populous a ‘cushion’ of warning so they don’t cry fowl. I just hope we don’t get an icestorm. Really doesn’t do good for the safety of a lot of people.

  2. Longview 400 ft says:

    High Temp was 36.3
    Currently 31.6
    It’s going to be fun to watch the temp drop tonight as the evening unfolds.
    NWS says 16 for a low in the morning, but I am going for 13 if the clouds do their part and part ways, LOL, I have about 3 inches left on the ground to help reflect any heat.

  3. Been snowing pretty much on and off all day here in Salem. Looks like we have another batch moving in. Been around 33-34 for the past several hours. Maybe this will knock it down below freezing for good.

  4. W7ENK says:

    Still haven’t seen a single snowflake here in my in upper Milwaukie neighborhood yet, though I can confirm by my travels earlier today that 1.5 miles to my South and 2 miles to my East begins the snow cover, albeit very little, just a dusting.

    So much for that sub-freezing high temperature today, topped out at 36 earlier. Try again tomorrow, I guess?

    Models still divergent going into the weekend.
    Flip a coin, roll the dice and make a wish!

  5. Paul D says:

    Looks like the arctic blast is being downgraded a bit. The 7-day forecast has some highs above freezing in it for Tuesday, Thursday and Friday.

  6. Like a Kid in Snow - Dallas says:

    I have been following this blog since the fun December 2008 storm but I very rarely post. I come here to read good forecasting from Mark. I am a weather enthusiast with no technical knowledge! 😉 I have to say, though, I am feeling like no one knows what is going on with the weather! Yesterday we had a Winter Weather Advisory for the morning and afternoon but all I saw was rain with some snow mixed in. All showers were to end by last evening but today I have had snow showers off and on all morning and I have a good 1/2 inch of snow on the ground. What is up with these surprise showers? I love snow so it is a great surprise but I like to feel confident in what to expect for the weather (the reason I come here) and I am feeling no confidence. 😦

  7. Diana F says:

    Some people have all the luck…


    “Three Feet of Snow at Mission Ridge, Cold and Sunny
    At Mission Ridge Ski Area, along the eastern slopes of the Cascades, there was an historic snow dump, with 39 inches falling within 24 hr. So much snow that Mission Ridge had to delay its opening today (open and packed right now).”

    • Well, it’s a ski area, probably with an annual snowfall of 200″ or more, so a 39″ dump, while unusual, is not as exceptional as it would be in a less-snowy climate.

      I’ve seen a town with an average annual snowfall of 50″ get 40″ in a single storm. That was definitely a disruption.

    • Diana F says:

      I’m still going with Cliff’s description…..historic….

    • Diana F says:

      Thanks Alan, rude comments are always appreciated. Cliff is an educated gentleman (u might want to google the definition), and I respect his opinion.

    • Wish the trolls would find something better to do, thanks for the info Diana. Light snow showers all day, I will take it!

    • GTS1K' says:

      Good grief,

      While tiresome, repetitive, off topic, verbose and extremely annoying, Farmer Ted/Scooter was/is not even in the same little>/i>league as A.S.Shole. It escapes me why he is still able to comment, given that, exactly none of his comments even rise to the sublevel of the recently “moderated” R.T. B. (AKA “Scooter”). (more later, if necessary)

      Given the content of his oeuvre he (Mr. Shole) should have been the gone after his first comment – let alone the consistently inane, crude and childish nature of the rest.

      Mystified , I am.

      Are there rules or not?

      It’s obviously your blog, Mark, but i fail to understand the rationale behind allowing such blatant trolling.

      Maybe I’m overreacting but.what does everybody else think???

      I can’t imagine anyone is actually frightened of this puppet??

    • pappoose in scappoose says:

      Mystified as well, GTS.

    • GTS1K' says:

      If you’d finished K-8, you’d be able to spell crybabies – then again, maybe not.

  8. JJ78259 says:

    Could it be another below normal month happening in the Northwest???? Two in a row!

  9. Fraser outflow is still at the breezy-but-not-windy range for me. Temperature is presently 35 here; so far it’s hardly arctic. 31 in Bellingham, 25 in Hope, so colder air is gradually starting to work its way in.

  10. JERAT416 says:

    Mark, please don’t make me a liar! People on my FB in the PDX Westside saying it’s snowing and I said no, you said no precipitation until the weekend. Could be a broken water pipe spraying into the air or snow blowing off trees. I stand by you forecast!

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

    Anyone want to put their two cents in about the latest batch of moisture wrapping around and about to pummel the metro? Snowing pretty good, and no sign of stopping any time soon by the radar…http://www.atmos.washington.edu/weather/radar.shtml

  12. Timenators says:

    Snowing with some sticking here in Sherwoood

  13. Sapo says:

    Going to be an interesting week ahead…Wednesday for now looks dry, mid/south valley could see 2-4″ however. As of latest runs the NAM and the GEM are really the only models still giving us precip on Wednesday, but a few small changes and we get a snowstorm. We’ll see.

    Saturday is looking very much like a snow/ice storm, probably initially starting as snow. Latest Euro gives 1-3″ snow, then maybe .5″ ice. I’d guess it would be more snow because the gorge may keep upper air temps cooler than modeled but who knows.

    • chris s says:

      To soon to start talking about what looks like Feb 1996 showing up in week 2 of gfs past few runs?? not sure what snow pack comparisons are from 2k-6k in the cascades, or coast range snow, but 3-4 days straight of tons of rain below 6k wont be pretty…..

  14. pappoose in scappoose says:

    National Weather Service Portland Oregon
    900 AM PST Mon Jan 2 2017

    .LONG TERM…Wednesday night through Sunday…Previous discussion from Sunday afternoon follows…Anyone have a coin
    to flip?

  15. JohnD says:

    Thank you for your detailed and passionate analysis Jake. Greatly expands and embellishes the likes of fairly one dimensional renditions from the likes of NOAA. Corroborates Marks overview too. Time will tell how it all plays. We all know that the odds always favor the warme Pacific. But who knows: This could be our year!

    Today–for myself and wife–it is a long walk in true wintertime temperatures!


  16. Alohabb says:

    Ever so lightly snowing in Milwaukee

  17. Brian Schmit says:

    Come join 1500 weather enthusiasts geeking out with pictures and weather maps on Facebook.


  18. Lee Wilson says:

    Just curious on something.
    What. Kind of ice storm would have to hit that froze the mamoths dead in their tracks?

    Well. Here in this area, we got walloped good in areas.
    Seen a guy with a foot of snow on his car…

    My thought…not cool….should that come flying off his car he’d be responsible for the damage, injuries or death.

    This snow was seat and heavy. With high moisture content.
    We hit 35 yesterday which now turned our streets in to ice.
    We won’t be driving any where today.

    Well not sure how much longer we will have free internet..

    Not sure what happened with Q Link.
    If they been hacked, they will have a storm of their own to contend with.
    At any rate happy New Years.

    And remember….. Icro Climates have their own little rules.

    Got to love that here in the Pacific Northwest.
    Hope you all remain safe and warm..
    Be thank full we don’t get the winter storms that take out the power..

    I may like to jib and jab….now and then but one thing I do take serious… I don’t take anything like having power for granted.

    Never say it won’t happen… Because that’s when you become a victim.
    On. The Flip side..one can’t be paranoid either.

    We have been very lucky here in the Pacific Northwest.
    A winter storm could nock out the power.

    Oh and prime exame of thinking it can’t happen..

    How about that mess a few weeks ago?
    If that didn’t teach people a lesson , well then, I don’t know what will.

    On a lighter side…

    Time to get some seedlings started for the Garden. Yeah hard to believe its that planning time already.

    Hey Mark…heres to hoping for No Green Maters .

    I think this year will be excellent for crops.

    Oh..and I better not hear of any water shortage this year.

    Because we have got to have a good snow pack this year..

    Speaking of which…what is the latest on that?

  19. Tyler Mode in Battle Ground says:

    Finally picking up a NE wind here. Temp is 31.5, DP 28.2. Just 7 mph so far.

    Had a few snow flakes this morning.

    • Paul D says:

      34 at my place in Hillsboro. A bit disappointing – was hoping for something in the 20’s….. 😦

  20. Joe says:

    Can I get a link to ECMWF?

    • Jake-(Gresham) says:

      Can we be friends? Exactly what I’d say.
      I put 3 links right bellow your post 30 minutes ago, lol!!!

  21. Jake-(Gresham) says:

    I don’t want to jump the gun but looking at the long range models:

    The Euro has us clearly socked into the cold Friday right before the busy weekend:



    It then only briefly shows this arctic air mass move on to the East Monday briefly:



    Then about Tuesday a resurgence of cold arctic air comes down from the North. This time around it does not come entirely come directly from the North over land. It partially comes off the ocean as well and not just over land / also what cold is left East of the Cascades.

    This is critical as it increases moisture content and also increases the chances of another weather system in general coming along with that cold. This is critical as too off shore and the air warms due to the ocean. Too on shore and we’re once again dependent on very aggressive weather system to provide the moisture.



    The big thing to take away however is that the Euro is saying this. As the more complex and stronger model, that is huge. However, the GFS has this all occurring sooner and has the recursion of cold air coming in by Sunday morning – instead of Monday morning.

    This 24hr difference while small, is significant. If the Euro assimilates the GFS in the next run and just bring this all about 12 hours sooner, to say Sunday night?

    That really starts to bring things into perspective. In short, what we want to see despite potential disagreements among future runs (which will happen!). We want the Euro to affirm and touch base with the GFS into this stormy pattern.

    As of now we’re looking at 8in+ from Saturday morning into Monday evening when things will be all said and done. That is a conservative number.

    • Jake-(Gresham) says:

      Apologies for the spelling. Promise I’m going to bed soon. Just wanted to give you new folks a chime! 😛

      Key point to take away. If models hold we’re looking at 2008ish. Maybe more (not less at this point!). If things start to fall apart it could get real messy (ice, flooding, ect.).


    • Jake-(Gresham) says:

      Something I forgot to add. The long range models also don’t have us in any significant manner leaving a cold arctic air mass until the middle of the month. If these models runs maintain.

      This first dry and cold week of the year may just be an introductory.

      But again, everything depends on what the models say from the weekend forward as the dynamic between moisture and cold air starts there. If the trend starts to go wet and warm.

      We’ll get out of this with just a rainy stormy weather Saturday morning. But the potential right now is huge for a very snowy / cold January like we haven’t seen in some time.

      What I personally don’t want to see is only a slight backing off. Then we get a ice encasement. Only way I can describe it. Really don’t want that.

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

      I appreciate your posts, enthusiasm, and analysis, and the pivitolweather pics! I just got home and was eyeing those maps for the weekend. I think they must have gone to the warmer side since your reports? As I understand it, to get a true snow signal at sea level here, you’d need those 850MB temps below (-6C? to -8) depending on a few factors. I’m looking at Saturday through Tuesday, and I don’t think they are going lower than – 3C currently. Just wondering if I missed something, or if that is because they updated from your forecast. Thanks again for your hard work, and analysis! HAPPY NEW YEAR AND TO SNOWY RELOADS TO COME!!!

    • Jake-(Gresham) says:

      Thanks Garron for the praise. Yea that level of depth is what we want however I didn’t worry so much on that in my overview that far out.

      That is something that needs to fall into place though for sure (or at the very least be available through the Gorge). Right now the long range models and Mark’s new forecast it appears we’ve regressed enough where that might not save us.

      The worst probability looks to be coming into view with a fairly big icestorm. I really hope this doesn’t come to fruition. Ton of more model runs to go. I’m really waiting on the next batch of runs. We’re totally in the icebox zone right now like the Grinch is out to get us or something. Really bad.

  22. Gregg in Bend, formerly Troutdale Gregg says:

    Mark, what do you see for us in Bend. Wednesday looks very snowy here in Bend.

  23. Mountain Man says:

    I must say, the 00z Ecmwf just in says days of snow and some ice perhaps… It’s not backing off.

    • Mountain Man says:

      Looking through the new maps, a good run for sure for several days of winter precipitation and east wind likely through all 10 day.

  24. Lurkyloo says:

    Nope, not accepting another ’04. Hated that one.

  25. West Linn 500' says:

    I know your comparison is for only one model, and it does not indicate duration… but, “… very similar to January 2004” sounds just a bit foreboding.

    We were shut in for five days, with thick ice covering everything – it was too slick to even make it out the front door. IIRC there were also blizzard warnings in east county.

    No snow here yet, tonight. Just a bit of leftover slush from earlier. We dodged most of it in Tha Linn

  26. Fraser outflow is here. Quite windy out on the Sound; the ferry rocked a fair bit and one wave hit just right: “WHAM!” and the whole boat shudders. Just mildly breezy here on the island. Looks like we may luck out and avoid an outflow windstorm and the associated power outages yet again.

    • Roland Derksen says:

      Yes, Abbotsford in the valley has been reporting wind gusts over 40 mph. Boy, am I glad I’m away from that.

  27. Jake-(Gresham) says:

    Thanks Mark!

    Flipping penguins and flying hippos! Why’d our ancestors have to be so good at settling so properly. I’ll never have the excuse to get this:

    Come on GFS!

  28. JJ78259 says:

    First Day of the year First

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