Mild Winter So Far, But Colder With Snow Close to Sea Level Ahead

9:30pm Sunday…

Here we are in mid-January, halfway through meteorological winter (December-February). We’ve had ONE significant weather event during that time west of the Cascades; the wind and rain storm earlier last week. It has been a very mild winter as well. By the way, I just confirmed the peak gust at PDX was 50 mph during the last minute of January 12th (11:59pm).

December 1st through January 16th has been the WARMEST 1ST HALF OF WINTER ON RECORD IN PORTLAND! You like that big red font? This comes with one big caveat. Portland has grown tremendously and we have an “urban heat island” now. It’s most noticeable at night. A lot more people live here compared to 60 years ago. That means even if the climate was not warming (it is), we would be seeing Portland’s average temperature rising due to that effect alone. But check out Redmond (little/no urban influence there). It’s the warmest since 1951! And Olympia has seen the 3rd warmest after 1951 & 1981. Going back 100 years, Salem has seen its 5th warmest first half of winter. My point is that yes, it has been a very mild winter…so far.

Snowpack is well below normal, running about 60-80% of average in the Cascades. Yet 2018, 2012, & 2011 La Nina years saw similar or lower snowpack at this point around Government Camp. Many of these years we play “catch-up” with snowpack in February/March. We’ll see.

Of course weatherwise it’s been a very slow winter (again) for forecasters but we think that will be changing as we head into a colder weather pattern. And yes, we may be flirting with low-elevation snow at some point in the next 10 days.

Quick Summary

  1. The next 7 days will be much drier than average, it’s possible we don’t seen any rain until NEXT Sunday
  2. There’s no sign of an “arctic blast pipe-buster” for at least the next 10 days. That is a big shot of cold air from Canada; think lows in teens or lower and highs around 30 or below. I don’t see that happening.
  3. Beginning next Sunday, expect a cold & wet weather pattern with heavy Cascade snowfall
  4. Beginning next Sunday, we may see our first widespread foothill and Coast Range snow plus there may be more beyond that. This winter, sticking snow below 2,000′ has been rare. That will change for the final week of January. If you live between 1,000′ and 2,000′, you can expect to see snow more regularly beginning next Sunday.
  5. AT THIS POINT, we do not have (sticking) snow in our forecast (for lowlands) through at least next Sunday. That’s because we don’t see a setup that would drag sticking snow all the way down to the valley floor, or sea level. But it may be close to sea level at some point in the 7-10 day range. Keep a close eye on that Sunday-Tuesday forecast NEXT week.

What’s Changing?

We have a strong upper-level ridge right over us and it’s staying put through Wednesday. This is the flow of air up around 18,000′ (500mb). I’ve annotated the ridge with a yellow line. This is Tuesday

By Thursday, a cold upper-level trough is dropping down the back side of the ridge as it backs off to the west.

But it appears just about all moisture will remain offshore, so we’re going with just a few light showers (rain) Thursday evening. Weather geeks will remember that THIS was going to be the big system that would drop south and bring in arctic air at the end of the week. That was on some models maybe 5-7 days ago. Now it’s just a weak ripple in the northwesterly flow. Then by Monday the 25th, a much deeper & colder trough is moving into the Pacific Northwest

This one is preceded by a stronger cold front and plenty of moisture next Sunday. Depending on the exact track of surface low pressure, this setup CAN bring snow to sea level. I’ve got two thoughts on that. First, neither the GFS or ECMWF models at this moment retain enough cold offshore flow to bring widespread sticking snow to the valley floor. That’s because the low is coming in from the northwest. Second, the air isn’t that cold to begin with and we’re quickly going to onshore (mild) flow. That’s almost always a snow killer. That system next Sunday reminds me of several during the 2007-2008 winter that brought abundant snow to Detroit, the Gorge, Coast Range, and the Cascade foothills. But not quite cold enough for lowest elevations to get in on the snow action. 850mb temperatures are forecast to be around -5 to -6…again, not quite cold enough for a big snow event in the metro area next Sunday. I think the ECMWF rain/snow forecast shows the situation well for Sunday night

Beyond that, the upper-ridging wants to move even farther west of us, allowing a cold trough to set up over the Gulf of Alaska and send cold waves of moisture our way. A quick animation of those upper-level heights from next Monday the 25th to Monday February 1st (a full week), shows the progression westward, along with the coldest air

The final image tells me a lot.

It says that beyond about day 10, we’re into a classic La Nina pattern that’s wet and cool. Tons of mountain snow, but not much chance for it in the lowlands. This will likely be the first big week of mountain snow this winter, maybe like the middle of last January?

Check out the ECMWF ensemble forecasts for snow. About 1/3 to 1/2 produce “sleddable” snow in the Portland metro area sometime in the next 2 weeks. I think that might be generous considering what I’m seeing right now.

You can see model forecasts of high temperature (usually a few degrees low) dip to a minimum early NEXT week and then rise again as we get more systems off the mild Pacific. This is the GFS.

One more thing that gives me confidence that we’re not headed into a major cold/snowy spell…the 850mb ensemble charts. Excellent agreement through the next 7-9 days, then a rise (warming). Almost no members below -7 through the next two weeks. This is just the ECMWF, but GFS is similar.

This wasn’t the case 5-7 days ago. As we get closer to a change, models come together most of the time and this is a good example.

That’s it for now. Of course even without a “major cold/snowy spell”, we can get an event where part of the lowlands get snow and that may not show up until just a few days ahead of time. I’ll be working regular shifts for the next 3-4 weeks as we wrap up this “winter”. We should still be having some fun even if no widespread snowstorm shows up in the valleys.

Make sure you follow me on Facebook @marknelsenweather, Twitter: @marknelsenKPTV, I update those far more often than this blog. And don’t forget our podcasts here: https://www.kptv.com/podcasts/weather/

Chief Meteorologist Mark Nelsen

54 Responses to Mild Winter So Far, But Colder With Snow Close to Sea Level Ahead

  1. […] atmospheric rivers moving into the area. And as Fox 12 Meteorologist Mark Nelsen pointed out in his most recent blog post, the first half of “meteorological winter” (which goes from December 1 to February […]

  2. Anonymous says:

    No he didn’t, he said one of many models shows that and others show some. That isn’t a prediction!

  3. JohnD says:

    Dr. Cliff Mass’s expertise and credentials are impeccable. His long standing Atmospheric Sciences tenure at the University of Washington speaks for itself. Have his forecasts ever been “wrong”? Of course. But his renditions are always highly and meticulously considered amid tried and true methodology and long term PNW residency. He is also a trusted colleague of Mark. In my view two of the very finest in our region.
    To say the least, it will be interesting to see to what extent—or not—Mark corroborates Cliff’s presentation. And to what extent it all plays out in the end, over the coming days.

    • Mountain Man says:

      Well said, and I have a ton of respect for Cliff! Also for Mark. If you want the best information you can get, those two are the best.

  4. Al koholic says:

    Cliff Mass predicts foot of snow Tuesday in Portland

    • Chad says:

      Old people are silly 😂

    • Larry says:

      even if that does verify, it is an absurd claim to make especially considering its the Willamette Valley we are talking about

    • Andrew says:

      haha I saw that. I know that conventional models really struggle accounting for the Gorge outflow impact and clearly the UofW model he uses accounts for more of the regional nuances. However, I’ll need some level of corroboration from Mark before bracing for anything like that. Cliff and his model are also basing that on low position a full week out which is a bit of blind throw of the dart if you ask me. Still pretty cool to see. Ultimate eye candy.

    • Paul D says:

      Predicting a foot of snow a week away – that’s gutsy! 🙂

      Better stop by your local supermarket and stock up on toilet paper!

    • Andy says:

      I saw the same info on another program…pretty interesting the connection with the cold in Russia will be affecting Canada in the coming weeks…hopefully it has an affect on us.

  5. Chad says:

    There is good chance most see a nice rain/snow mix this weekend. Hopefully you all enjoy our one shot at winter 😂

  6. Weatherdan says:

    Latest 16 day meteogram has us with an atmospheric river hitting Oregon around the 1st. They give Eugene 8.32 inches in the 10-16 day time frame. But at the end of that time they also have the fzl in Vancouver plunging to sea lvl. Might get interesting, or not. Peace.

  7. Andy says:

    Best chance for snow this winter at lower elevations looks to be Saturday night into Sunday morning including the Willamette valley… something to keep an eye on as we approach the weekend. Fingers crossed.

    • Roland Derksen says:

      Same forecast up here, so we’ll see what happens!

    • Andrew says:

      EURO is pretty solid with at least a dusting. But conditions are so borderline that I think we’ll need to wait until the 24-48 hour window before we know if that’s realistic. I’m hopeful this will be first of a few flirtations with snow over next few weeks as we appear somewhat locked in to a relatively favorable pattern. I know it’s awfully far out and nothing but eye candy at this point but GFS hinting at more legit arctic air around turn of month. So much has to align but gives me hope we’re just about to enter an active stretch. We’ll see.

      • Andy says:

        Noticed the same for the beginning of February and the cold seems to be locked in BC and western Canada for a good source of arctic air for us…though like you said best to wait 3 to 5 days out.

  8. tim says:

    I think it’s safe to say winter is over 00zgf doesn’t offer much hope does it as well as the gem.

    • Zach says:

      We have all noticed that anytime you see an iteration of the GFS leaning on the side of “warmer” you come on here and make an obtuse post which is clearly shown to be wrong a few days later.

      • W7ENK says:

        It really is ridiculous, isn’t it? This is the dude that was saying Winter was over back before Thanksgiving. I guess he just can’t help himself, troll’s gonna troll.

  9. Roland Derksen says:

    Beautiful morning here- so nice to see that sun and blue sky… Anyway, looks like my first freezing temperatures will come later this week(i,e 28F or a bit less) And with some luck, a bit of snow on the weekend. It ain’t much, but at least it’s worth anticipating.

  10. Lynn Colvin says:

    Say it isn’t so!!! No snow storm??? Nuts!

  11. Al koholic says:

    Global warming is a fraud

  12. Paul D says:

    This winter is going to go down in the record books as being extremely boring. What a bummer! The flowers are already popping up and my grass is looking shaggy – bad signs!

  13. Mountain Man says:

    Tanis, I don’t mind your posts I like most all of them, sometimes a bit much on the analysis and a bit to little on fact. At least it’s life in the comments, been trying for life in the comments myself!!! You know! It’s plenty easy enough for someone to skip if they want to look at the tools, having their own battle… lol!

  14. Tanis Leach says:

    Post 4/4 My definition for winter

    Everyone has their own definition. This one is just my opinion combining my previous analysis projects:

    Winter: Veterans Day to St. Patty’s Day or the fork (whichever comes first)
    Deep Winter: December 8th to February 7th.

    Deep winter is when frequency of both arctic blasts and snowstorms 2″+ are more common.

    Since school is picking back up, I’m not going to do another one of these for at least 2 months, unless it is coinciding with a school project. Comments, questions, future suggestions, and criticisms are always welcome. Also, since I do want to get involved in more online weather groups, if I do more of these, in order to prevent more wordy posts like I’ve done here (looking back it can come across as rude so I apologize for that) I would like to propose a google doc format where I post the link to it, with the subject of it for those who want to read it. I do my typing in Microsoft Word but its easy enough to transfer. Thoughts on that?

  15. Tanis Leach says:

    Post 3/4 Deeper analysis:

    On the timing: The earliest arctic blast occurred during 1955, beginning on the 12th of November, while the latest was February 2014, ending on the 8th of February. I’m using days below freezing to determine start end dates since both met condition 4. Granted, Downtown data (looked at less due to changing locations more often) showed a major arctic blast February 25-28th, so it is possible to get them after but rare. That is after adjusting for climate trends.

    Since I looked at arctic blast I also looked at winter high temperature. There was no winter, even after accounting for climate change that had its lowest high temperature being 40°F or higher 2 years in a row. Also, the highest, lowest high temperature of any winter was 42 degrees after climate adjustments back in 1967. The highest low temperature of any winter is 27°F. Both we’ve been below so far this winter.

    There does appear to be a tilt towards La Nina winters for arctic blasts, but p-values rule that it is not confident enough to reject other natural forcing involved.

    Also interesting, the 7 day period with the most common arctic blast time was January 29th to February 4th, with 6 involved here. The steep drop off afterwards puzzles me a little bit, I’d expect a borderline arctic blast somewhere around Valentine’s day as the latest. Before December 4th (start of 1972 arctic blast) it also gets more sporadic, but the drop off is smoother than its February counterpart.

    Arctic blasts during a winter generally indicate some sort of snow, only 1 winter that contained an arctic blast had no snow (January 1974), or less than 1.8 inches for that matter (2010-11’s total).

    Last post: Combining this and the snow data to give a timetable for winter beyond the usual December thru February timeframe (or November 15th to February 14th).

    • Mountain Man says:

      Hmmm makes me wonder if you had used minimum temperature instead?

      • Tanis Leach says:

        My wording may have been poor so let me see if this clears it up. I used both minimum high temperatures of a period and minimum low temperatures, but intermixed them here. I do have all minimum temperatures back to 1940 downloaded on my computer if there are questions/concerns involved.

    • Mountain Man says:

      No you’re good, maybe very good, it is more like trying to describe something that should actually be grafted? I mean the lowest record temperature gets lower right, but the highest gets higher right… Into the very beginning of February, right? So making a long explanation is far less effective than a picture with a short explanation of what you are trying to tell people. Make a visual presentation, of exactly your 4 part thing, will be much better! I don’t because I’m old and not that enthusiastic anymore lol

      • Tanis Leach says:

        That makes me want to do the google doc format more, since I can post graphs like that there. It was difficult trying to explain out something I graphed instead. In the future, I’ll just do that.

  16. W7ENK says:

    Thanks for the update, Mark. Really looking forward to a pattern change for the colder. Two days in a row spent working on projects out in the yard, no sleeves, in mid January? The neighborhood kids were running around all weekend in shorts and no jackets!

    Absolutely ridiculous.

    Oh, and Tanis? No disrespect, but too many words, bruh. I don’t think anyone is reading all that anymore. I’m not, I gave up a couple weeks ago… 🤷🏼‍♂️

    • Anonymous says:

      Um some of us read it all and he’s a student and thats our future so don’t knock it, he’ll balance it out between being young and being middle age and I got that guy pegged to be something we’ll all see like awesome from lol 😝🤣

    • Anonymous says:

      Oh and Eric, no disrespectful intentions, love your regular contribution

    • Tanis Leach says:

      None taken. I have been known to give either too much detail, or too little. I understand if you don’t want to read because its wordy. As a possible middle ground, I could in the future create a google doc link to anyone with link for those who want to read it for lengthy analysis (>250 words)

    • …even over here the lack of winter is insane…we have snap dragons trying to bloom, and the holdover hornets are warm enough to be moving around; one found it’s way to my mouse, which i didn’t realize until i put my hand on it 😦

  17. Tanis Leach says:

    Post 2/4: ALL arctic blasts by my definition:

    Reminder of my definition: One of the 4 factors must happen to qualify a cold snap as an arctic blast for Portland:
    1. -12°C 850 mb temp over Salem.
    2. Lowest high temperature of 26°F or -3°C or below.
    3. Lowest low temperature of 14°F or -10°C or below.
    4. A stretch of 5 days failing to get above freezing or 3 days failing to get out of the 20s. (No blast has met this category without meeting one of the others)
    Regionwide is when this happens at Portland and Eugene (or factor 1 is met), and major is when all 4 happen.

    The following list is done with adjustments for warming winters so they are all as if they were happening in todays climate. .2 degrees were added to each decade before 2010, .4 before 2000, and so on. Enso cycles are included after 1950. To make it quicker I only put in Portland data, so no classifications occurred.

    The list in order:
    January 1943
    January 1949
    January and February of 1950 (3 in the winter) (La Nina)
    January 1954 (El Nino)
    November 1955 (La Nina)
    February 1956 (La Nina)
    January 1957 (Neutral)
    January 1962 (Neutral)
    January 1963 (Neutral)
    December 1964 (La Nina)
    December 1968 (El Nino)
    January 1969 (El Nino)
    December 1972 (El Nino)
    January 1974 (La Nina)
    December 1978-January 1979 (one long one) (Neutral)
    January 1980 (El Nino)
    December 1983 (La Nina)
    November 1985 (Neutral)
    December 1985 (Neutral)
    February 1989 (La Nina)
    December 1990 (Neutral)
    January-February 1996 (La Nina)
    December 1998 (La Nina)
    January 2004 (Neutral)
    December 2008 (La Nina)
    December 2009 (El Nino)
    November 2010 (La Nina)
    December 2013 (Neutral)
    February 2014 (Neutral)
    January 2017 (La Nina)

    Total arctic blast months: 33
    November: 3
    December: 11
    January: 14
    February: 5

    El Nino: 5 winters (multiple in same winter count as 1)
    Neutral: 8 winters
    La Nina: 11 winters
    Pre-ENSO: 2 winters
    Total winters with arctic blast: 26
    Chances of getting one out of any year: 32.5% or just under 1 every 3 years.
    Longest stretch without one: January 1943-January 1949, 5 winters without one.

    A little more detail is in the next post. Though I’m hungry, I’ve spent the last 5 hours finishing this up and some schoolwork so next post will be 30-45 min away.

    Note: Even though I didn’t use Eugene data, I needed it for a class tonight using data from the 90s and found that January 1993 qualifies as an arctic blast down there but not in Portland. Don’t know of any other ones yet since that was not my primary focus.

  18. Tanis Leach says:

    I’ll start by saying that my arctic blast frequency analysis is complete, and I am writing up a quick summary when this is done. As such: post 1/4.

    Upcoming: We are now within 7 days of the upcoming event and this is what I think will happen as of right now. Snow levels bottom out at around 1000 feet, though more likely 1500 feet at this time. It is possible flakes get mixed in down below but I’m not confident on that right now. If we do get anything, I would argue Sunday night into Tuesday morning of next week. Still too far out to decipher what will happen there. I’m not confident we’ll get a lot of precipitation out of this until Sunday. No matter what happens, the mountains will get some much needed snowpack from this. High temperatures I don’t think will drop below 40 degrees, but I am confident of at least one low in the 20s at this time before Sunday.

    Those are my quick thoughts. It does seem to mirror what Mark says, so I’m glad I’m not the only one seemingly conservative on this. Granted, as the curse goes with my running friends, it only snows when its not predicted so that could me something if you believe in it (I don’t)

    • Tanis Leach says:

      Forgot to add, thank you Mark Nelsen for both this and your podcast. I especially enjoy the podcast format since I can tell that you and your team have a fun time creating those. Plus it gives me a few laughs.

  19. Anonymous says:

    Thank you Mark 👍👍👍

  20. Mountain Man says:

    Oh man loving the operational ECMWF at day 10, juice is just getting ready to the north in a very favorable flow, that is actually Arctic air, actually somewhere close, haven’t even seen that for a long time. Okay I know the cold eye candy is just a letdown, but what are you supposed to think when you get a favorable pattern from the north and there’s just no cold air up there at the time except then on that model? Nothing has changed otherwise in the 00z runs or ensombles from earlier. GFS is back to outlining, GEM is slightly warmer yet, Just the ECMWF keeps being a bit more exciting and the others are 1000 ft and above for any snow. My gut says this might get better over the next few days.

  21. boydo3 says:

    Time for blog snow!

    • …jeezus i hated when that got turned on way back when…used to slow my browser down to a crawl trying to do reload after reload to get new comments when things used to get real busy here 🙂 …and… howdy, boydo!

  22. Mountain Man says:

    Here’s a story for you guys. So almost 20 years ago, I was almost fired from ODA, but I eventually quit instead. Because they where so sure that what seemed to them like all the cutting edge prediction at my fingertips should yeld better results in the 8 to 14 day timeframe, funny since that was like super primitive model information then when compared to today’s models which still can’t get it right past 7 days or sometimes 3 days. Forecasting is a very brutal job.
    When we move forward into this more favorable chilly forecast, remember, things can change fast, just a little different placement in a surface low pressure can mean a big change in the weather, even though the model information is to warm, so you think. Low placement, think New Year 04 for example. I deleted this all in the last blog comments. Mark just said, it could show up right before it happens, that’s still how it often happens it seems to me. The only thing that is apparently obvious, this general change, gives you all a wonderful chance that something will happen in the last week of the month. How could you ask for more when you’re seen nothing?

  23. geo says:

    Yeh, maybe some conversational snow?

  24. JohnD says:

    First?
    Thanks Mark. And we all know that you don’t pull punches. So it unfortunately appears that nothing overly dramatic is likely within the next week or two. Still close enough for most of us to not lose hope for “some” kind of low elevation winter weather action. Amid a winter like the one this has been so far, I’d consider it a triumph to some evening be able to look up at a street light and seeing a few flakes mixed in!

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