Tuesday Evening Update

Another 24 hours of model runs to look over…so much fun.  Looks like the weather is still going to get colder next week.    I will be on vacation and away from my computer a good chunk of the time from midday Wednesday to Saturday night.  If you are a new commenter on this blog, your comment may get approved in less than 24 hours.  And possibly no new updates on this blog until that time.   If the action starts to look REALLY good again early next week in the models, then I’ll post from a hotel room I suppose.  I’ll be out-of-town part of that time.


Highlights for the regular folks out there that don’t need all the meteorological detail:

  • Nice weather continues through Friday
  • Showers arrive Saturday
  • Rainy and breezy Sunday
  • Rain/snow showers possible Monday before we dry out.  Details are still very uncertain with respect to getting snow down below the foothills.  We may just see a dusting on the hills Monday and then we dry out.
  • Then cold and dry next week with high temps around 40 at best

Travel looks excellent across the region through Sunday, snow levels will stay high in the mountains through Sunday afternoon, so passes may remain clear through that time.


What has changed in models/maps/my thinking the past 24 hours?

1. General trend for Sunday-Tuesday is NOT AS COLD.  That’s across all the main models
Instead of seeing models with -10 to -15 degree 850mb temps, they seem to have all stabilized around -7 to -8 later Monday through early Wednesday.  This evening’s 00z runs of GFS and GEM (Canadian) are only showing thicknesses bottoming out around 520dm.  That’s cold, but not big arctic blast material.  That’ll still give us high temps close to 40.  Or 35-40 with a cold east wind.  Here is the 12z ECMWF ensemble chart, note lots of members still much colder than the operational run on Tuesday/Wednesday though.  All hope is not lost (yet) of a colder arctic blast:


and the 18z GFS chart.  It was right in line with the average of its ensemble members through Monday, then a  little on the warm side Tuesday/Wednesday.  Shortly after this post, a new chart should be out.  I’ll attach it to the bottom:


2. GFS speeded up the timing quite a bit last night and this morning, but has now slowed down to show almost exactly what the ECMWF shows.
GFS has a +5 still Sunday afternoon, the ECMWF was up around +2 at 850mb at the same time ahead of a wet Pacific cold front.  This does keep passes clear for the end of the weekend; very good in this case.  Sunday should be a mild and rainy day.  I saw another media site online article headline; something like “snow could arrive in the lowlands Sunday”.  That’s not going to happen.  Take a look at the Sunday 4pm map of the ECMWF:


3. Strong ridging still forecast in the Gulf of Alaska and into Alaska; generally a very good setup for cold airmasses to move south into the Pac. Northwest
All models in very good agreement on this, but the ridge is a little closer now.  Note the Thursday morning 500mb chart from the 00z GFS:


4. NOT AS WET.  Except for the 12z ECMWF, there isn’t a whole lot of moisture once we get pass the average-looking Pacific cold front that moves through here Sunday night.  The 18z and 00z GFS are pretty much dry all of next week after midday Monday.  Just a repeat of what we’ve seen the past week, except about 10-15 degrees colder.  Brrr!  We’ll see a lot more overnight lows in the teens if that’s the case.  No more 50 degree days in this scenario either.  The 12z ECMWF was different, showing several waves riding down in the northerly flow with a snow chance later Tuesday.  Then it undercut the upper-level ridge to our west, allow a surface low to suddenly deepen offshore and then slide across Oregon.  That would be a big snowstorm across most of the state later Wednesday and Thursday.  What do you bet it won’t be there on the 00z run?  We’ll see.  But this WAS a beautiful map:


Offshore flow, a cold air mass, and a very wet low sliding by just to our south…nice.

So, right now I see a slight chance for snow for some of us if everything were to turn out just perfect early next week, then a cold spell the rest of the week.  Just not a huge arctic blast, and likely no big snowstorm either.

That said, when you have a huge upper-level ridge to the west and northerly flow, something could easily spin up in the models the next few days and put a snowstorm into our forecast…stay tuned.

Have a happy Thanksgiving!

00z GFS ensemble chart goes here:


Ensemble average was a little lower than the operational run Tuesday/Wednesday, more like -10.  Notice NO warm members (warmer than -5) during that period.

Chief Meteorologist Mark Nelsen

679 Responses to Tuesday Evening Update

  1. Kenny says:

    The new 00z GFS hammers Northern California valley with a monster snowstorm early next week, maybe their biggest ever. A slight track northward would hammer Oregon.

  2. boydo3 N Albany says:

    Over a week ago when this arctic event started to show on models I said I wouldn’t get excited til it was within 3-5 days. So I started getting excited a day or two ago. Now the models have done their funny little dance to screw up a perfectly good set up for cold.
    Hrmpff! Pfffftt goes the good stuff.

  3. JohnD says:

    My weather optimism is in a pretty good gear today. It ought to be an interesting weather week coming up. Good rain event today followed by much below normal temperatures in a day or so and who knows?–maybe at some point over the coming days we will develop a bit of wintry precipitation!

    Oh–and by the way–for the benefit of Dharmabum and others who might be unsure: GOLU is: “Go Outside Look Up” !!! (In the end, our most reliable “model”!)

    Have a good day. I’ll be checking back this evening. NOAA too. Hopefully Mark will be chiming in today as well!

  4. Heatblizzard says:

    Also we did a partial wash of the car at the broken car wash since it was the only one open at the time we did it.

  5. Heatblizzard says:

    If it does NOT snow you have me to thank because Dad put our snow tires on the car two days ago.

    Hopefully this snow is not going to be a total bust like George Bush’s “Read my lips” lie. Bad joke. :p

    • Mark says:

      Or “If you like your health care you can keep it” equally bad. ; ) Two political phrases that will go down in infamy!

      And yes, we blame your Father for putting on snow tires. Shame on him. He has now ruined our chances at snow – certainly so! ; )

      Keeping a close eye on the northern Yukon temps. Now as cold as -41 F. We shall see where the bulk of this slides…

  6. Lauraholic says:

    It is almost time for my favorite model run.. the GOLU run! Time to make some hot chocolate and enjoy what mother nature decides to give us!!

    If nothing else, today should be a lovely rain storm! =) Good thing the boat has a heater!

  7. alohabb says:

    Local mets backing off on the direct hit cold and going more with a glancing blow. Should be interesting non the less

    • justwatching says:

      NWS has removed snow from the forecast for the central valley as of this morning

    • justwatching says:

      I think I will return this forecast to walmart and buy a snow making machine

    • David B. says:

      There *is* some variability in the model runs but there is *nothing* to indicate that the coming cold snap is in fact a complete bust. It’s a case of more cold vs. less cold, not a case of cold vs. no cold. I would not be surprised at all to see the models flip once again in favor of the “more cold” solution.

      I’ve mentioned here before that in my experience it’s easier to get snow after the cold air is in place or as it is departing than when it is coming in. And indeed, both the Portland and the Seattle NWS extended forecasts do now mention a chance of snow later in the week.

      The latter is reason to not give up hope, particularly when it has also been my experience that most arctic outflow events do come with some snow somewhere; the completely dry ones are distinctly the minority.

      • Ryan says:

        I’ll wait for Rob to confirm a bust. After reading the Portland area forecast discussion, I’m not hearing anything that would depict even a minor bust.

    • Lauraholic says:

      The wind woke me up this morning. I hope it gets more exciting from here =) Sturgeon fishing is always more fun in the rain and wind 🙂

    • David B. says:

      @Lauraholic – It’s definitely a blustery one up here in Puget Sound country today, too. The first part of the show (mild, wind, rain) is on!

  8. Ryan says:

    Extremely windy/gusty here in Bend! And it looks like the moisture is just starting. Have a feeling this front could be pretty dang strong since it’s only 7am!

  9. WEATHERDAN says:

    Mark is back and lurking. I know this because those those little snowflakes that he sometimes puts on the blog are there.

  10. Model Rider says:

    Weird. With the current model runs channel 8 has Saturday colder than Tuesday on their 7 day. Strange with how conservative they’ve been.

    • Mark says:

      If the bulk of arctic energy does slide east, as the overall model trend is suggesting, even the EURO 00z’s latest run, it make be that KGW pulled off the most accurate long-range forecast. Wow…

  11. pappoose in scappoose says:

    While we wait for the freeze you in your tracks east winds, we’re gonna have to dodge pineapples!


  12. Rob - Southeast Portland says:

    00z WRF-GFS still is very cold for PDX, but especially Gorge east, deep arctic air Columbia Basin for an extended period of time. East wind will be strong for many days, so even if it’s -6c to -10c 850mb temps, 925mb temps are really cold -12c to -15c Gorge, -15c to -18c Columbia Basin. This guarantees that modified arctic air will continuously flood westward into PDX possibly for a week(or longer? unsure). East of I-205 it’s going to feel every bit like an Arctic Blast.

  13. paulbeugene says:

    Euro 00z significantly less cold in the day 6-10 period.

    UKMET holding firm with cold through day 6-7.

    GFS backing out a little

    Canadian backing out a little.

    Going to be a cold week but highs in the 20s will remain east of the Cascades.

    Still think some low temps in the mid-upper teens away from the gorge possible.

    No snow.

    Enjoy the freezing rain.

  14. Jethro says:

    I predict that whatever happens next week will be somewhere between “Kenny” and “No Snow”. 😛

  15. Kenny says:

    I would be concerned at the new 00z GFS Operational run but it doesn’t have ensemble support. This is why the OP will revert to the colder ensemble runs as we near the event. Some of the ensemble members have actually gotten colder as we near the event, a very good sign. I suspect at the latest we will still have warm GFS OP runs at 18z tomorrow. By the next 00z GFS run tomorrow, we should see it deliver more to the ensemble mean.

  16. Rob - Southeast Portland says:

    00z EURO through FCST HR 120 mirrors the 00z GFS operational. Still cold, but not bitterly so. Time to throw out the bitterly cold NAM and 00z GFS Ensembles? It’s never this difficult tracking things. The models have been so poor.

  17. AdamInAumsville says:

    00Z GFS operational on the warm side of things again. Ensemble mean close to -13C at its coldest on Wednesday. Operational doesn’t get below -8C for the same time period.

  18. Model Rider says:

    Rob, wanting to hear your expertise. With a pattern like this, and you know how dry it is on the east side of cascades, is there a chance of better precip than usual on the eastside compared to normal with this setup because of offshore flow?

  19. No Snow says:

    Bust-o-rama 2013

    • No Snow says:

      The GFS is accurate. It’s just not what you all want to see. Why is the most realistic model the “outlier?”

      • Ryan says:

        How is it the most realistic model? The Euro has been MUCH more consistent this whole time. And the GFS isn’t even all that bad anyway. You’re just a troll.

    • Ryan says:

      Where are you seeing a bust? Latest runs are colder on every single model besides GFS, and even that isn’t bad. What bust?

    • runtmc says:

      Bust-o-rama 2013. Ingenious. Somebody revoke No Snow’s trolling license on grounds of egregious unoriginality.

    • boydo3 N Albany says:

      No Snow; the arch nemesis of the blog ..
      Much like Prof. Moriarty
      Elusive and yet…….

  20. blowmedown says:

    00Z blows badly and im not going to get very excited anymore about even the possability of even a modified arctic anything if this keeps up. Seriously never seen so much variatios and model changes like this in a long while! Wow! GFS is whacked and on crack!

  21. alohabb says:

    How are we, or are we not, looking for a mini-windstorm tomorrow as the front SLAMS through??

    • dothgrin says:

      This is when something happens this week no one expected. Time to see how much snow hits on the eastern slopes of the Cascades and then helps enhanced the cold blowing through the Gorge.

  22. JohnD says:

    I am an active “buff” like everyone on this blog; but in times like these I can’t help but feel this whole thing is a bit bizarre to say the least. We have been LIVING in the cognitive this week (e.g. “will it, won’t it?”)–when all the while in the interim GOLU has given us a really nice week!–sustained freezing mornings and for he most part DRY and scenic afternoons!

    Now we are finally on the precipice of some significant changes and after all this time some seem to be disheartened. I mean come on, we are not asking for (nor should we at all necessarily be expecting) the blizzard of the century!!!

    But there ARE, by consensus, some real cool changes (literally and figuratively) ahead–worthy of a lot of intrigue! And at this point, who knows how awesome they may or may not turn out to be.

    For me–certainly at this point in the season–ANYTHING is better than nothing!

    • dharmabum says:

      John, thanks for your insight, well needed, especially at this Thanksgiving time, it is good to be grateful for all the weather we receive here in the NW, not to get too absorbed with relentless number crunching and disappointments at man made, ever changing future prognoses. The relatively warm moist air today was certainly a pleasant change!

    • Lurkyloo says:

      I’ll agree with that, John. As my kids say, “You get what you get, so don’t throw a fit!” (“Do as I say, not as I do” should be their motto … Ha.)

  23. B1900 Pilot says:

    There be snowflakes! That’s always a good sign. :^)

  24. Rick says:

    We have all this excitement coming our way — and no Mark— come on Mark we need your input.

  25. Timmy_Supercell (Klamath Falls @ 4200') says:

    Last night’s moisture certainly was a surprise, just about every website / tv news station called for literally 0% chance of precip. Woke up this morning to see the ground was wet. First time I can recall that in quite a while.

    • Timmy_Supercell (Klamath Falls @ 4200') says:

      But wasn’t a major a failure on the forecast; today was another sunny, nearly clear day in the basin.

    • justwatching says:

      I seen last night on the Crater Lake cams that it was falling as snow. Most of the south central was below freezing when the moisture made it there. I bet you had flakes in the air at your house @ 4200′ if it was wet this morning.

    • ocpaul says:

      Bruce Sussman mentioned chance of light drizzle last night. (for Friday night)

  26. dharmabum says:

    I like what Cliff Mass says on his blog:


    “The media, and some of us meteorologists, have been focused too much on snow and cold.. Mother nature is like a magician: keeps us watching the wrong thing, while the real story (heavy rain and flooding), always in the open, is ignored.”

    “The heavy rain will cause the rivers to rapidly rise, with some reaching flood stage. Take a look at the current forecast from the NWS River Forecast Center for the Snoqualmie near Carnation. This is a major flood.”

    Wow, this could be a sneaker for some folks.

  27. Kenny says:

    Tonights 00z GFS and EURO will be the biggest runs ever. The 00z is the most accurate of the runs with the most data so we SHOULD see more agreement between the operational and ensemble runs. I have a strong feeling that the GFS op runs have had a strong warm bias because it was tweaked last year to fix it’s cold bias, now it’s too warm. The models are underestimating once again the power of the Fraser River and Columbia River outflows as they do not understand that cold arctic air will easily arrive in the western lowlands because of this outflow, that is my best guess as it way the op has had a warm bias.

  28. alohabb says:

    Wow…possible Wind Advisory for PDX ahead of an arctic front that could bring snow…..Its almost a weather geeks Christmas wish come true!!! What an active week ahead!!!

  29. Benjamin (West Salem) says:

    Snow on the blog…. awaiting tonight’s 00z model runs.

  30. Josh Gardner says:

    Interesting data from the WPC and their 3-7 day outlooks. I believe PDX AFD mentioned their favoring of the EURO/UKMET blend and these forecasts seem to back that up.

    3-7 Day Max Temp loop

    3-7 Day Min Temp Loop

  31. Marcustheweathernut says:

    18z Greatest Forcast Slump model…… Cannot be trusted…… I’m banking on the euro:]

  32. Rob - Southeast Portland says:

    18z NAM Summary
    Pretty much the same through FCST HR 60 with the initial trough energy splits. HOWEVER upstream energy is seen in NWT. FCST HR 72 this progresses south. FCST HR 84 it digs back into BC and an even colder, deeper trough is set to drop down over WA/OR. The Block leans a bit tilts west and looks pretty good. This looks more like the EURO at 500mb after HR 84. Running the 500mb loop shows it is beginning to dig very nicely southwestward over WA. Thickness and 850mb temps fall rapidly after HR 78. REAL potential. First sign of the models blinking shifting towards GEM/EURO? unsure.

    18z GFS through 156 is a bit colder west of the Cascades, but the biggest difference I see is a colder arctic high in Montana, and deep arctic air is locked into the Columbia Basin.

    We definitely need energy in NWT to dig back into AB/BC HR 60 – 72 or else we see a glancing blow and slow moderation. If we do see a solution similar to the 18z NAM/12z EURO/12z GEM/12z UKMET it will be significantly colder with a possible reload.

  33. Kenny says:

    The biggest thing we know is that at least modified arctic it will hit the western lowlands, even with the warm biased GFS. If that happens, models are always too fast to push it out. The arctic air isn’t going anywhere.

  34. AdamInAumsville says:

    18Z GFS poor. Interested to see what the ensembles are.

  35. Kenny says:

    The new 12z EURO gives the PNW a monster snowstorm next Friday/Friday night. The GFS seriously needs to consider retirement.

  36. runrain says:

    NWS is calling for a low of 16 here in PDX later next week. Cold!!

  37. Josh Gardner says:

    I’m very close to legitimately disregarding to operational GFS. It’s very out of touch with the NWS favored solution (for more on that check out Shawn Weagle’s AFD today) and has been by far the least consistent. I should note this is not from a bias standpoint of wanting cold, but simply the performance of EURO along with support from GEM/UKMET and even to a point the GFS ensembles makes it hard for me to put too much stock in the GFS.

    I’d love to hear what others think on this though!

  38. Sapo says:

    Is snow possible in the Saturday/Sunday period? Looks like we could get some precipitation, but most models are showing a warmup in that period also. Any thoughts?

    • Ryan says:

      No, Saturday/Sunday will be all rain in the valleys. Snow level won’t be at the floor until Monday night, could be some

      • Ryan says:

        Meant to say could be some precip late Monday night, but not much. This is more of a cold air event, but late next week could be interesting.

    • Sapo says:

      Ok. I was talking about Saturday and Sunday, December 7th and 8th, late next week.

      • Ryan says:

        Ahh ok, then yes. There is a chance of that at this point. Anything is possible once you have the cold air in place.

  39. Marcustheweathernut says:

    Can we believe these ensembles????? Would be awesome if it came to be!!!! http://www.wetterzentrale.de/pics/MT8_Portland_Oregon_USA_ens.png

  40. dothgrin says:

    I am not sure if this was answered, but the concern that this rookie sees is a heavy amount of rain on Monday followed by freezing temps, especially on bridges and above 200 feet. With the amount of moisture in the air, I see an ice problem for Tuesday’s commute no matter if there is enough in the air. Any thoughts?

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