Snow For Some Sunday AM

11pm Saturday…

A cold front moves into Western Oregon and Washington tomorrow morning.  At the same time we have a cool airmass overhead, along with colder and dry air pouring out of the Columbia River Gorge.  The combination of these means we have a marginally good potential for snow to the lowest elevations again.  ANYONE IN THE LOWEST ELEVATIONS MAY SEE SNOW FALLING, BUT ONLY SOME AREAS WILL GET SNOW STICKING ON THE GROUND.

Similar to Christmas Eve morning, pinpointing the locations where we see snow to the valley floor is tough.  Unlike Christmas Eve, everyone will get steady precipitation west of the Cascades by 10am.  So instead it’s all about temperatures then for your Sunday morning snow/rain forecast.  Here’s the forecast graphic I used at 10pm:

MarkSnow_PDX_2Elevations

I say west metro for the lowest sticking snow because there are strong hints based on the easterly flow and models that cold air will be deepest as it banks up right along the east side of the Coast Range and Tualatin Mtns.  This is similar to the “Forest Grove Effect”, but kind of a weak version of what we’ve seen in the past.  The 00z WRF-GFS and our RPM have a similar look.  Tomorrow morning would be a good time to be in Vernonia, Buxton, Banks, or Forest Grove.  Possibly St. Helens & Scappoose too.  Also I think a dusting to 1″ is possible anywhere higher up in the West Hills.

Your next question is…”what if I live at 600′“?  Then you’ll likely see conditions between those two text panels.  No matter what someone tells you, we can’t forecast snow level with that much detail.  I’ve seen snow level forecasts for 250′, 750′ etc… in the past.  That drives me nuts.  Precipitation intensity and location will affect snow level far more than elevation in most cases.  For example at 1,000′ I had no snow Christmas Eve morning, yet people near sea level around Woodland/La Center had snow because heavier showers were falling in those locations.

For those of you travelling through the Coast Range tomorrow, I’d delay until the afternoon hours when the snow backs off.  Roads should be better at that time.

For the Cascades and Gorge, the issue is that a lot of the moisture won’t even make it that far.  As a result I said just 1-2” in the Gorge and it’ll probably be mainly wet on I-84 through the entire day.  A few more inches in the Cascades won’t make any different on the snow-packed roads either.

Chief Meteorologist Mark Nelsen

93 Responses to Snow For Some Sunday AM

  1. Any time the intensity backs off here rain starts mixing back in. It was nice to watch at least.

  2. pappoose in scappoose says:

    Snowing and sticking. About a half inch on everything. Road is slushy but deteriorating fast.

  3. Jonathan SEPDX says:

    Had big wet flakes for about an hour. Soon as it started sticking to my roof the rain returned

  4. Jane-Forest Grove says:

    Been snowing here for a few hours. Temp dropped to 33. Trees, grass and cars covered. Roads look OK so far. Very pretty as long as we don’t freeze tonight. :-/

  5. christina malcolm says:

    here in east Vancouver it has started snow/rain mix with some snow only showers. we didn’t get rain this morning like forecasted. we didn’t get precipitation until this afternoon and it is going to cool off soon. with rain falling now and forecasted (morning perhaps overnight tonight). I wonder if we could see any accumulation. just a thought.

  6. oldwxwatcher says:

    Started snowing here in east Portland around 2:25 PM. Temperature has fallen from 37.1 to 33.6 and still dropping. Lawn in nearly all white now. A very nice after-Christmas present, for sure.

    If you weren’t lucky enough to get in on this little snow event you can still see it “snowing” at your place by going to the site listed below and entering your address. Then click Go and look through the window.

    http://pusher.com.au/clients/pusher-christmas-2012/

  7. Diana says:

    It’s been snowing at 1000′ on Mt Scott for about 1 1/2 hours. Starting as small flakes, going to big fluffy snow, now back to small. Slight accumulation even on the road, but that’s because no one drives on it. Temp is at 34.2

  8. Washougal 1100ft says:

    Finally starting to snow in the gorge see how much moisture makes it this way with the wind.

  9. Pete says:

    Moderate snow and beginning to stick on the lawns here at NE 60th/Glisan. Temp 35F.

  10. Lurkyloo says:

    Yay!!!

  11. At about 20 feet in elevation here and the snow is slightly sticking on the grass and houses. Probably due to the heavier showers.

  12. Snow actually coming down pretty nicely now here in the lowest elevations at Fairview and Blue Lake.

  13. Now moderate snow with good sized flakes and a breezy east wind. Starting to see perhaps initial stages of accumulations on the grass, vehicles. This is awesome!

  14. Big ‘ol floppy flakes here in NE Vancouver now. Really didn’t think wet bulb would get it done.

  15. Peter (Fairview 20') says:

    Few flakes in the air here by blue and Fairview lake down to the lowest elevations

  16. Max in Fairview says:

    Starting to see a few flakes east side now.

  17. There is something magical and joyful about watching the snow fall while listening to Christmas Music. The Christmas tree and all its lights shining in all their glory. The Christmas lights on the house standing out against the snowy background. It’s wondrous and it’s what Winter is all about. This is great.

    Merry Christmas. Happy New Year. Thank you, El Nino.

  18. Sapo says:

    My deck and grass could end up with 1/2 or 1″ of snow by the time this is done.

  19. Jonathan SEPDX says:

    Light rain/snow mix in inner se currently. Best I’ve seen all season. Still to gd warm though

  20. Hal in Aims says:

    36 and bone dry here………..

  21. Wet snow has resumed for me. Several years ago, when moving to Bainbridge Island, I wondered if there would ever be any “Hood Canal effect spillover” on days when places like Shelton, Belfair, and Seabeck were getting sticking snow (due to cold air piling against the eastern slopes of the Olympics) while most other lowland locations just got rain.

    Looks like the answer to my question is YES. Though it’s mostly just flakes in the air that at one point were falling hard enough to make the grass slightly slushy. Still beats getting nothing but 36 degree rain.

  22. geo says:

    Absolutely nothing here in sw gresham-even the east wind died down to nothing.

  23. Tanya says:

    Snowing pretty heavy in Scappoose near Hwy 30.

  24. GTS1K' says:

    Snowing for the last hour at varying rates – maybe 3/4″ on the deck. Snow starting to stick on NW Skyline.
    32.1

  25. Alohabb says:

    Heavy snow falling in aloha. Yard now turning white. Temp 34. Dropped FAST in last 2 hours l

  26. Just glanced at 12z GEM/ECMWF they both keep a strong, persistent Columbia Basin cold pool with potential snow event Tuesday night/Wednesday. A prolonged ‘fake cold’ regime lasts through at least day 10 possibly longer as arctic air filters into eastern Washington at times and that only reinforces the cold pool. I even see some signs that PDX may be closer to freezing for high temps into January simply due to constant strong and cold east wind thickening the cold layer progressively over time. It will be essentially a bit similar to if a backdoor modified arctic front was located from the Gorge eastward.

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