Transition Day Goes Smoothly…So Far


We are slowly transitioning out of the cold arctic air mass this morning.  Temperature stayed in the mid-upper 20s overnight in the metro area due to the cloud cover; practically tropical compared to the previous 4 mornings!


We escaped without major issues for the morning commute; models did a great job showing extremely light (or no) precipitation overnight in our area.  Looks like just about no one had more than 1/2″ of snow and just a few pockets of freezing rain.  If we don’t get any freezing rain before noon, we are probably clear for this event.  Remember from past events that for freezing rain to “stick” and cause issues on roads, the temperature needs to be 30 or below, especially during the day since even on a cloudy day we get some energy from the sun to warm road surfaces.  At 10am, ODOT sensors on Highway 30 around Sauvie Island, I-205 at Division, and a couple of others show road surface temps now at freezing or above.  We should top out slightly above freezing today, then with some spots of clearing drop down below freezing again tonight.

As a result, at this point the afternoon commute looks even a bit better than this morning.

There is a chance we get a spot or two of freezing drizzle or a flurry tonight, but most of the energy for lifting the cloud layer to produce precipitation will be gone. 

We did have interesting and unusual weather in the Columbia River Gorge the past 24 hours…it was WARMER than here in the metro area.  I see The Dalles made it up to 38 in the middle of the night, same thing at Hood River.  Wait a minute…isn’t it always colder in the Gorge at the end of a cold spell?  Not this time, we had weak westerly flow through the Gorge, and some warmer air from above mixed down with those west winds.  That will come to an abrupt end tonight when surface high pressure strengthens on the east side of the state.  Thus it will be a significantly colder day in the central/eastern end of the Columbia River Gorge tomorrow and the gusty east wind will return.  Think of it as the colder east side air “sloshing” back into the Gorge overnight.

So what happens beyond tonight?  A very slow weather pattern with a few weak systems.  One on Thursday and another possibly later in the weekend.  I don’t see significant rain, or mountain snow, until the middle/latter part of NEXT week.  Our drier than average weather pattern we’ve seen since October continues with upper-level ridging nearby.  A very persistent pattern this cool season so far…

Will precipitation start as snow or freezing rain Thursday?  Very unlikely for most of us.


  1. No strong east wind, or even much at all, to supply a reinforcing shot of cold air out of the Gorge.  We will moderate temps quickly with a southerly wind above the surface.  By Thursday afternoon the actual snow level is over 4,000′.
  2. Atmosphere overhead would only support freezing rain, not snow.  That’s pretty clear on forecast soundings.
  3. Precipitation arrival appears to be at midday.  Unless temps are 30 or below late morning to midday Thursday, freezing rain won’t be able to freeze to road surfaces.  If the system were to rush in at 7am I could see pockets of freezing rain Thursday morning after a mainly clear night Wednesday night.

I could see a better chance for a few pockets of freezing rain in the Gorge…maybe.  This is also going to be a weak system without much wind or precipitation.

Chief Meteorologist Mark Nelsen


118 Responses to Transition Day Goes Smoothly…So Far

  1. paulbeugene says:

    I’m still freezing my butt of here in EUG and here I see another arctic blast on Euro at hr 216!
    -17C temps BLI
    -11C PDX

  2. MasterNate says:

    Down to 18 already. Looks like a redo later next week. Maybe we can get some snow out of this one, eh?

  3. Marcustheweathernut says:

    Arctic blast number two!!!!! Esenbles look good for snow with cold!!!!!

  4. dale says:

    25 out in Dayton. I did not think we was two get down that low..

  5. dothgrin says:

    Apparently it is going to get very, very, very, very cold tonight! (This was on the NWS Web Site tonight)

  6. Muxpux (Castle Rock 175') says:

    Sitting at 32 here but everything is still wet, so yeah, and Kelso is stuck at 34.

  7. Ryan says:

    Anyone have a link to the latest GFS or ECMWF ensembles? Call me dumb but those are the only models I can interpret.

  8. Marcustheweathernut says:

    00z gfs shows snow in metro area 9 days out!!!!!:)

  9. AdamInAumsville says:

    12Z GFS still looks sort of interesting in the long term. Something to keep an eye on. My highs/lows for the arctic blast:

    Date High Low

    12/4 36 18
    12/5 31 14
    12/6 29 23 1.75″ snow
    12/7 28 6
    12/8 26 4
    12/9 31 8
    12/10 34 21*

    *So far (current temp)

  10. Ryan says:

    27 in NW Beaverton. Didn’t expect it to be this low already….interesting.

  11. Roman~Snow-Zone-Monmouth, Elv. 223' says:

    21.7F out now.. Should be back into the teens tonight!

    • AdamInAumsville says:

      Down to 20.0 now. Dewpoint 15.3, so definitely heading into the teens tonight. Still lots of snow around my place.

  12. dharmabum says:

    Reality check: Many days below freezing, many low and daytime high records set, i.e.; Eugene with a -10 low and many cold mornings to follow, Redmond -26 both of these were 2nd on the all-time lows. I have lived in the NW over 60 years, born in Omak moved to Pendelton at 1 and to Gladstone by age 2, the rest of the time I have been in the Portland area and have had a career working outside in the winter for Weyerhaeuser Company. This has to rank as one of the all time cold spells here in the North Valley. If we would of had a blanket of snow we all in the Metro area would have had near all-time record lows. I don’t think we will see anything like this soon. (presently here at Barton we are at 25.9, now that’s cold!

  13. Andrew (Beaverton, OR) says:

    Already down to 29 here after a high of 34.

  14. Sapo says:

    12z, 18z GFS hr. 204-240 bringing back cold air with plenty of precipitation with it, ECMWF also has cold air returning December 19.

    • snodaze says:

      cold rain is all, — in that view brohammer. But close?… very close given the time of year. 🙂 — two or three weeks either side? (no dice)… lol… But we have hope…. Yes?

  15. Model Rider says:

    If the models keep going with the pattern for next week when are u going to start analyzing them again Rob? And I mean from run to run like this last episode.

  16. Muxpux (Castle Rock 175') says:

    Really foggy up here. About 33. Drippy but still snow on the driveway and grass.

  17. Andrew (Beaverton, OR) says:

    NWS mentions up to a half inch of ice possible??? That would be very bad news.

  18. poolsidemike says:

    I like this little snippet from the just released Special Weather Statement…”THE FULL POTENTIAL OF THIS EVENT COULD MATERIALIZE WITH

    My minimal weather knowledge but being a native Portlander tells me that we will wake up Thursday to 38 degrees and rain.

    • Ryan says:

      I’m in! Who said the blast was over?? This helps give us a couple more days for the models to confirm next week’s potential blast too. It will be easier to model ride if we get some fun along the way!

  19. Ryan says:

    Loving the special weather statement, they are not agreeing with the warmup that the models show on thursday. Seem to be going with at least a couple hours of ice, with the potential of a much bigger event if the south winds don’t get down low soon enough. Should be above freezing by Thursday evening, but for Thursday morning/afternoon it could be “ICE, ICE, BABY!” Bring it on!

  20. W7ENK says:

    346 PM PST TUE DEC 10 2013

  21. Andrew (Beaverton, OR) says:

    Interesting to see the NWS lowered the expected high from 40 to 34 for my area on thursday with freezing rain….

    • Ryan says:

      Yea they are definitely concerned we won’t warm up fast enough. Issuing a special weather statement shortly, according to the AFD.

  22. Taylor says:

    What’s this? Am I actually hearing we might have a second artic blast event coming our way? I will be shocked if that happens. According to the NWS we typically only see one of these events if we get one per year.

    • David B. says:

      And we typically see more overrunning than we’re seeing when this one is ending.

      “Typical” does not mean “always”. I’ve seen winters with two arctic blasts before.

    • dharmabum says:

      We have had several arctic events in one winter, and technically this is not winter yet!!!!!!! “Keep your powder dry”

  23. Model Rider says:

    And the 18z keeps the chances of a huge omega block setting up in eastern pacific again mid next week. Sweet!! Now on to 00z runs tonight. I wouldn’t be so excited about it being so far away but we have ensemble and operational consistency for many runs in a row now. Both gfs and euro. Canadian as well I might add. This is for you Rob, hmmmm

  24. Ryan says:

    Mark, looks like your forecast high of 34 for Portland will be spot on. I thought we’d get a bit warmer, nice call!

  25. Well , arctic blast has come and gone. With a “gradual moderation”, even in the south valley with it molasses like cold Airmass. I would have thought that lack of overrunning type winter precip transition event would have been the more likely scenario. But then again, I may be biased by my own experience growing up in Vancouver WA in the 70’s 80’s. It always seemed that freezing rain was the inevitable transition event, at least in the gorge. Something like odds of overrunning frozen/freezing precip south valley 10%, Salem 15%, portland metro 60%, east PDX metro 80%, gorge/Corbett/TTD 90%. Guess my experience is wrong…. “Gradual moderation ” certainly is boring…

    • Typo: I thought moderation the LESS likely scenario. ..

    • Ryan says:

      VERY gradual. It’s still 28 in Eugene, 30 in Corvallis, and 35 in Astoria. Still arctic to me. And we still could get that transitional event. I don’t think you guys realize just how gradual this warmup will be. There is ZERO south wind forecasted until late Thursday! It takes days to get the air scoured out without south wind.

    • yeah, theres no south wind, but theres no east wind either, so whats moderating us is the Ocean. with the flow coming off the relatively warm Pacific instead of the bitter north, and not drawing out of a cold pool east of the cascades, it just slowly warms up.

  26. WEATHERDAN says:

    So the models are now trending towards another Arctic outbreak with a snowstorm in a little over a week. Well I am not riding the models but I have been saying for awhile that my instinct tells me that this last cold snap was just the beginning of a very active winter. Pete Parsons back months ago pointed out the similarity between this year and 1968. He just might be right. September through this week has seen 4 extreme weather events. Might a 5th be just around the corner. I don’t know but it is looking like it. By the way, in December of 1968 we had a cold snap with some snow in early December. Then between about the 8th to the 18th it was 45-52 with a fair amount of rain. Then we had more cold and snow between the 19th to the 22nd. Then a rainy Christmas with another Arctic outbreak just before the new year. This year won’t be an exact match, they never are. But it might be a similar situation where cold snaps happen frequently from Thanksgiving through early February. Peace and a very Merry Christmas.

  27. Ryan says:

    Still 28 in Eugene, 33 in Hillsboro, and even just 35 in Astoria. Hard to say the arctic blast is “over”. Might be slowly coming to an end, but 35 in Astoria is still arctic in my mind. And we should all be below freezing again tonight. Tomorrow should be the first noticeable warmup, and even then we MIGHT reach 40, while again dipping below freezing tomorrow night. If the moisture came in earlier(wed night/early thurs), could cause a real icy mess. So in my opinion, the blast is not “over” yet. You can say that Thursday when the south winds really kick in. 36 hours left of this!

  28. Taylor says:

    36 degrees right now in Clackamas, OR. The arctic blast is over!

  29. 33 degrees here. First time above freezing in 139 hours (December 4th, 5 pm). Wow…it’s been a while since we went that long!

  30. Jake says:

    I’m no weather guy, but thought I’d give an update from up north. Things are very icy with freezing drizzle continuing. Secondary roads are treacherous around Kalama.

  31. Rob - Southeast Portland says:

    So it looks like Arctic Outbreak #1 is in the books…. Slowly moderating in/around PDX metro now. I doubt we’ll see any frozen precip Thursday too. So now the $62 dollar question is #2 around the corner? 12z GFS op and ENS were good and encouraging. Seems the trend that began with 00z EURO/GEM op and 00z EURO/GFS ENS/6z ENS continues.

    It’s nice to see things start to evolve offshore with the ridge and Bering Sea block after day 7. It looks real similar to our last pattern, but I see a few key differences. The westerlies are held back much further to the west near 170 W to the date line, sharp S.E. US ridge evolves after day 7-8. Block is near 150 W, but may retro back towards 155-158 W. Jackpot pattern. The trend is building momentum and it’s promising. I suppose that’s as far as we can speculate right now.

    • Ryan says:

      Hey Rob! Welcome back, we missed ya! You we’re pretty much spot on with your model analysis for this arctic blast, so it will be fun to follow your thoughts on next week’s outlook.

    • JohnD says:

      You rock Rob! Thanks for your always compelling
      AND astute commentary. It has been a fun ride so
      far and upstream looks to be something that we
      can realistically hang our “weather hopes” on!

    • David B. says:

      I forget… who is it that’s been writing the song lyrics here? We need one called “The Snow Will Fall Here Tomorrow” to the tune of “The Sun Will Come Out Tomorrow” from the musical Annie.

    • dothgrin says:

      We should have known this would not be much since you were relatively quiet!

    • runrain says:

      Ha Ha! I am not sophisticated enough to be able to write mashups to show tunes, David B., but thanks for the suggestion! But not to worry. If the weather gets real slow, I’ll try to come up with something to fill the lull!

    • David B. says:

      Just took a look at the lyrics and it’s real easy. Here’s my attempt:

      The snow’ll fall here tomorrow
      Bet your bottom dollar that tomorrow there’ll be white
      Just thinkin’ about tomorrow
      Clears away the cobwebs and the sorrow till’ there’s none

      When I’m stuck with a day that’s mild and rainy
      I just stick out my chin and grin and say oh

      The snow’ll fall here tomorrow
      So you got to hang on till’ tomorrow, come what may!
      Tomorrow, tomorrow, I love ya, tomorrow
      You’re always a day away

      When I’m stuck with a day that’s mild and rainy
      I just stick out my chin and grin and say oh

      The snow’ll fall here tomorrow
      So you got to hang on till’ tomorrow, come what may!
      Tomorrow, tomorrow, I love ya tomorrow
      You’re always a day away

      Tomorrow, tomorrow, I love ya tomorrow
      You’re always a day away …

    • Ben T says:

      Ugh Hank did we not get extreme arctic air?

    • Ryan says:

      Are you kidding me? He was spot on with the extreme cold temps, days before any local weather people mentioned it. And he got the precip right too, as the north had very little and the south valley got a lot. Can you explain what he got wrong?

    • poolsidemike says:

      “Hank” whoever you are…why the pot shot? Please tell us/show us where Rob was anything BUT spot on with this event.

    • JohnD says:

      Jerks not allowed. We are all friends here.
      PLUS Mark pulls the unkind trouble makers. So
      that is that!

    • ocpaul says:

      Oh no…Annie ear-worm!!:-)

  32. Kenny says:

    The new 12z GFS ouput has 0.74 inch liquid precip when it is cold enough to snow. This is 7.5 inches of snow for PDX, some places more, some places less but a major widespread snowstorm. My forecast would be anywhere from 6 to 9 inches as of right now starting next Thursday evening to Sunday evening. If the cold air gets here a little sooner, we could have even higher totals. High temps will be below freezing starting Friday of next week so the snow will stay as even colder true arctic air arrives after the snowstorm(s).

    • Mark says:

      Several GFS runs in a row now are turning us back to cold. I hinted at a possible setup a few days ago, but that was 240hrs out and only a glimpse via the EURO 00Z. The offshore high still isn’t where it needs to be, but this is 9/10 days out, so anything can happen. The models giveth and taketh away…

      Possibly flirting on the 19th – 21st for some wet snow in areas? Well, something to watch, as Kenny pointed out.

    • BoringOregon says:

      Still calling for arctic air. By January 10th, and a foot or more of snow :)…..

  33. W7ENK says:

    Treacherous conditions inside The Dome this morning, for sure! Easily the heaviest snowfall accumulation of the past year. First thing I did was measure the snow depth on my glass top table out back. My walkway was nearly impassable, and I don’t think my grass will grow back next spring…

    See for yourself:

    • SnowedIn - North Plains says:

      Did you get ahold of the President so you could personally request some disaster relief too?

    • David B. says:

      Count your blessings, the westerly flow aloft put us squarely on the lee side of the Olympic Mountains. Result:

    • Longview - 400 ft says:

      Your picture is so funny!!! I am so glad you finally got some snow regardless the amount.

      I tried to explain to my wife why I was laughing, but one has to be regular on here to fully appreciate this joyous occasion with you.

      May your next snow event be weeks or days instead of years!!!!

    • W7ENK says:

      I can’t, SnowedIn. Phone lines are down! Actually, my house doesn’t even have a phone line hooked up to it and I haven’t tried my cell…

      I was so ecstatic this morning, I almost considered skipping work so I could scrape up all the snowflakes that fell in the whole neighborhood and making a small snowman, but no. Work beckoned louder.

      Maybe we’ll try again next week? I sure hope so!!

    • pappoose in scappoose says:

      Commendable job even getting to work, W7. Don’t know how you got a trail blazed through the drifts!

    • Jakob Fisher says:

      I’m lucky enough to also live in the dome…actually, I hate it. I seriously think it has something to do with the waste treatment plant. All that methane causes tropical like conditions.

  34. W7ENK says:

    It’s over.

    1024 AM PST TUE DEC 10 2013

  35. Aloha Rainshadow says:

    Hey Mark, do you like what the 12z, 12z ensembles, Euro and GEM are hinting at late next week?

  36. Kenny says:

    Score, score, score, score! The new 12z GFS ENSEMBLES agree with the Operational and some are even colder! The true arctic air is coming back, this time with plenty of moisture!

  37. 30.5 here and freezing drizzle continues. There is a light coating on branches etc. But nothing major.

  38. Ryan says:

    And this one is officially over! 😦

    Although I must say, the NWS is MUCH more bullish on the threat of freezing rain on Thursday. I trust Mark more, but it could be a GOLU day for sure.

  39. schmit44 says:

    Lets hope the models give us an arctic reload in about 10 days or so.

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