Why is there a Snowflake in the 7 Day Forecast?

For the first time this year, it seems appropriate to add two snowflakes to the 7 Day Forecast.  I’ve hidden them pretty well, but they are there.


Twice in the next week, and for the first time this season, I see sticking snow at least down to 1,500′, and possibly a bit lower.  That would be Saturday morning and again next Tuesday morning.    Now just to be clear:


This isn’t a pattern where we get sticking snow down here in the city. but when I woke up and looked at the maps I noticed two things:

1.  Our RPM has speeded up the timing of the arrival of precipitation Saturday; right at daybreak.  The GFS is similar.  It also brings at least a mix of rain/snow into the northern Willamette Valley.  It is probably slightly cold showing actual snow accumulation at the lowest elevations here in the metro area at that time.   This model did pretty well with the lowlands last winter; in general when it showed such low elevation snow it actually occurred (somewhere in the valleys).  Also, the WRF-GFS soundings for that same time are very close to snow.  At the least they are cold enough that we should get sticking snow down close to 1,000′ when the precipitation starts.

2.  Cold air behind Monday’s rainy & windy system is even a bit colder than what’s coming in Saturday, but we have strong onshore flow (coming off the mild ocean) at the same time.  We don’t have that Saturday morning. so a different situation.  Also on Tuesday morning it’s off/on showery weather.   This means that sticking snow at that time is extremely unlikely in the lowest elevations, but near/above 1,500′ you could see a few inches.  The ECMWF was just about the coldest model for that morning.

If you plan on driving over the Coast Range Saturday morning, it appears to be quite snowy.  Same thing in the Cascades and higher elevations in the Columbia River Gorge from Cascade Locks eastward.  All areas will be clear Saturday afternoon as the snow level jumps up to 2,000′ or higher.

Chief Meteorologist Mark Nelsen

79 Responses to Why is there a Snowflake in the 7 Day Forecast?

  1. Snowing, sticking (see webcam by clicking my name)

  2. Joshua in Lake Oswego says:

    Coldest temp of the season already here. 33.6 on my cold biased thermometer. Bring it!

  3. bgb41 says:

    Tonight at midnight is the deadline for the Winter 2012-2013 Weather Frequency Contest. Here is the link to submit your guesses.

  4. 00z MM5-NAM Analysis

    Roughly 974mb low moves onshore in central Vancouver Island http://www.atmos.washington.edu/mm5rt/data/2012121500.naminit/images_d2/slp.54.0000.gif
    A fairly sharp gradient swings inland onto the Washington Coast with the tightest found from Kelso to Tacoma.
    http://www.atmos.washington.edu/mm5rt/data/2012121500.naminit/images_d2/slp.60.0000.gif Perhaps a Wind Event north of PDX, but not concerned for the Willamette Valley.

    Wind gust model isn’t very impressive either http://www.atmos.washington.edu/mm5rt/data/2012121500.naminit/images_d2/wgsfc.60.0000.gif
    Non-event probably. Let’s see what the GFS/WRF shows regarding this feature, and then move onto the potential snow Tuesday or beyond….

  5. UW 00z MM5-NAM is not working for me. Anyone else having issues with this?
    The NCEP NAM worked fine and it shows a strong, compact 976mb(roughly) low moving onshore between Forks and Tatoosh Island.

    I’m really eager to see the higher resolution models on how they are handling this, depth, and how the gradient is shaping up. Wind event/storm looks quite possible now, especially north of Kelso throughout western Washington.

  6. pappoose in scappoose says:

    Glad the models quit squabbling over where this low is gonna go.

    National Weather Service Portland or
    222 PM PST Friday Dec 14 2012

    A potentially much stronger system is expected Sun night/Monday.
    There will be plenty of over-running activity sun with snow levels
    lower than what is given by the traditional 1000-500 mb thickness
    values. Expect snow levels sun to be 1500 to 2500 feet…but rising
    in Lane County Cascades and foothills Sun afternoon as stronger warm advection develops. New European model (ecmwf) model has come in line with the other models…making fairly good agreement as to the details of this system. Models deepen the surface low to around 978 mb and bring it onshore northwest Washington early Monday morning. All models show strong southerly winds along the coast with this system and expect a
    High Wind Warning will be needed. Models maintain strong gusty winds as the front shifts inland and will need to watch for possible Wind Advisory over inland valleys. This is a much wetter system and precipitation will at least start out as snow down to 1500-2500 feet. However snow levels will rise dramatically Sunday evening. Likens

  7. 00z GFS in 2 1/2 hours
    00z ECMWF in 5 hours 18 minutes

  8. alohabb says:

    Windstorm Sunday night?

  9. Gabriel says:

    Getting some chunky rain down here in salem now. Any news on the low snow level this week?

  10. Hard to even focus on weather or the models, but I’m trying..

    Well 18z GFS is still cold with the trough Monday-Wednesday with 850mb -8c and 518 thickness shown. Unfortunately there is too much west or southerly component shown below 2500′, so I bet snow levels will be 500′ or higher….The trend I hate the most with the past 2 runs are the ridge axis is too far west and the Columbia Basin isn’t as freezing cold… I hope 00z brings back the colder solutions…

  11. swift says:

    First and foremost, my condolences to the innocent victims with what happened at Sandy Hook Elementary school today. A school is a place of peace and learning and this should not ever happen. May those who lost their lives including the 20 innocent children rest in peace. This is a horrible act that I hope never happens again. I hope the families of all those involved find peace in however long it must take, my thoughts and prayers are with them all. Today is not a day to talk about weather, there are more important things in life.

  12. alohabb says:

    Hows the weather looking for next few days? We gonna have a windstorm?

    Need a distraction

  13. alohabb says:

    What is this world coming to. Prayers to all those kids and their families.

    • gidrons says:

      What kind of a piece of $&^% murders a kindergarten class, and what has this society come to? There’s no punishment great enough for that *^$#.

    • alohabb says:

      Feels like there is no where that is safe anymore. My wife was run down in her car by another driver recently and you really begin to wonder what has happened to peoples minds! Praying for all those families

    • lurkyloo says:

      I have 2 kids in elementary school. Can’t imagine this kind of tragedy. So incredibly sad and utterly horrific. Cried most of the morning. Praying for them …

    • Chris s says:

      Just awful, I can’t begin to imagine the grief those parents must be going through, my prayers are with them. 😔

    • W7ENK says:

      What the hell are you people talking about???

    • alohabb says:

      W7. Gunman went into Elementary school killing 27, 18 of them kids.

    • W7ENK says:

      Oh Jesus… Where???

    • W7ENK says:

      NVM, I answered my own question… 😦

    • I haven’t been online or had the TV on yet today. I loaded up the Blog to tell you all about the 12z runs that aside from the trough Monday-Wednesday(850mb -8c, 517 thickness) that the run wasn’t very good either GFS or ECMWF, but NOW I read your comments and I am like? “What?… What are they talking about?” but I just found out and I’m literally speechless having no idea what to say.

    • pappoose in scappoose says:

      Speechless is where I’m at as well.

    • 20 Children killed ages 5-10 I believe. Children? Why. I think I’m pretty good with my words and often have a lot to say, but right now it is too numbing and shocking to comprehend this. You just sit here watching this on the news, you hear what they are saying, but it’s like your brain makes no sense of this. Thoughts and prayers to all families involved who’s lives have been forever changed.

    • Update……. 27 childern 7 adults Rip truely a very sad day for all.

  14. Hal in Aims says:

    has been snowing very lightly here for the last hour or so……

  15. ocpaul says:

    35.4 degrees at the low tower sensor. 1043′

  16. cgavic says:

    It’s snowing at our house in sandy at 1,100 ft.

  17. Tues/Wed next week look really close for low level (valley?) snow. But SW winds will no doubt keep it from sticking at the lowest elevations. 😦

  18. Pika-Yacolt says:

    Snowing in Yacolt 900ft. I hope it’s not going to last long.

  19. W7ENK says:

    39 degrees in Clackamas/Happy Valley
    Splat test = positive.

    38 degrees in Milwaukie
    Splat test = negative.

  20. Punxsutawney (aka HIOPHIL) at work by Sunset High elev ~280 says:

    Apparently it was snowing heavily around 3:45am up at OHSU. Not really sticking to the roads though.

    • Carrie says:

      It’s snowing here in Washougal. It’s a very light dusting of snow, but enough to turn everything white. Kids are super excited as this is their last day before the holidays. We are at 1400′ and it’s 34 degrees.

  21. Wet snow falling here, 34F. Prelude?

  22. Next week trough more impressive 850mb -8c thickness 518 really close to snow at valley floor. Oh and extended period(FCST 192 beyond) much cooler too. Columbia Basin colder too high temps in the upper 10’s to mid 20’s and lows 10’s to single digits 0’s. I like this a lot.

  23. 6z GFS to FCST HR 192(No real point looking after resolution change) is almost pure gold.
    FCST HR 144

    FCST HR 156

    FCST HR 180

    FCST HR 192

    500mb pattern evolves very good except ridge axis needs to be 7-9 degrees to the east. One heck of a strong block develops amplifying well north into Alaska and beyond possibly introducing cross-polar flow right out of Siberia. Westerlies are shut off and no energy crosses the date line, so no worries about the block pinching off. This is the first run I can recall showing this kind of block, so to me, this shows a lot of promise. If 12z continues this I think there is reason for optimism. We’ll see….

  24. bgb41 says:

    12/13/2012 Oregon (All) Temperature Summary

    High:53 at Port Orford (US( 90 ft) & RED MOUND(1753 ft)
    Low: 40 at Portland/Sauvie(20 ft) & DW2682 Portland(213 ft) & ROCKWY Rockaway(450 ft) & WH6KO St Helens(79 ft)

    High:23 at Rim(7050 ft) & Rim(7050 ft)
    Low: 2 at KIRK (4519 ft )

    Largest Diurnal Change: 34 degrees
    CRANE PRAIRIE (38/4 ) (5500 ft )

    Heaviest Rainfall:
    0.65″ at YELLOWSTONE MTN.(3080ft)
    0.52″ at PEBBLE(3450ft)

  25. Josh Smith Stayton (475 ft elev ) says:

    Where are the links again to all the weather maps at? Looking at the charts. Gonna be a very cool and showery period. At least there are no pineapples or intrusion of warm air that bumps snow levels too extremes.

    Rob, what you think of this current Saturday morning/ Tuesday morning chance of snow showers?… Is it just a mainly Portland east wind event or do i have a shot of seeing it here in stayton. I just moved here from south Salem. So im not sure if the south wind effects the foothills of the mountains like the valley does. Any information would be greatly appreciated. Thanks

  26. 00z ECMWF
    Leaps and bounds better than 12z or previous runs. The splitty pattern and cut-off lows are gone. Also, the trough digs a bit more southward. This is quite close to being cold/snowy for PDX.

  27. 500mb pattern was much better and really close to delivering for PDX… Improvements at least. 00z EURO says? …

  28. germantownsummit1000' says:

    Man I’m glad I live up here.

    I’ll be chaining up the plow tomorrow…


  29. paulbeugene says:

    As my pro-accuweather account lapsed…I don’t have access to the ECMWF long range output…so here’s the interpretation of it from Brett Andersen (of Accuweather):


    It should be noted that ECMWF long range (outside of ten days) is not to be taken as Gospel.

    • 00z GFS was much nicer tonight….. Snow for PDX possible now.

    • We need everything to line up right…. Marginally possible… Fake cold air to assist? … Wishful thinking I’m sure 😆

    • SnowedIn - North Plains says:

      This “fake cold” is really a chilly east wind, so we could actually get some “Forest Grove effect” out of that, right?

    • Alan says:

      His long range ECMWF is always fun to look at, but isn’t really worth a snowflake (sadly) since he changes it all the time. It looks good now for us, but probably won’t next round. Christmas didn’t have us looking wet/cold last go around. I really hope he’s accurate…ha!

    • lurkyloo says:

      Great. I just ran out of firewood … I never do that. Maybe a new snow indicator — Mark goes on vacation = snow. Lurky runs out of wood = snow. ??? Facepalm! 🙂

    • “SnowedIn”
      Yes that’s exactly what would happen, generally with a fake cold setup areas with gorge influence + anywhere that stays socked in would have a better chance, and knowing what I do about the effect out there it would be a higher chance.

  30. pappoose in scappoose says:

    Should the flatlanders put on the studded tires? Hahaah!

  31. Hal in Aims says:

    thanks for noticing, Art.

  32. MasterNate says:

    Those little lights are not twinking Clark. I only see one snowflake in the 7 day, not two as Mark teased us with.

  33. One of the reasons why I wish I lived about a 1000′ up this time of the year……….Being only 200′ doesn’t cut it most of the time…

  34. Mark, did Bobby take over your blog? 😉

  35. W7ENK says:


  36. SandBurnt says:

    Thanks for the update Mark. Love the Blog. I am so ready! Bring on the Snow!

  37. chris says:

    Man i wish i lived higher up at times like these, my 600ft will not do much but maybe living further north from Portland helps? it did last winter. 🙂

  38. *BoringOregon* says:

    Well, I hope we get some snow up on mount hood at least. I live about 1,000′ thank we might get any snow? kgw said up to 4” of snow next week?

  39. Sounds good to me! At least something somewhat exciting!

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