Snow Outlook For This Weekend

Here’s what we are thinking for the lower snow levels this weekend:

As mentioned in the previous post, there’s nothing too exciting coming except that most of us will at least see snow in the air sometime between Saturday evening and Sunday night, but it’ll be tough to see much accumulation to the lowest elevations.  I mentioned this type of setup 8 days ago during that “winter is cancelled” diatribe during the 10pm newscast.  Sure, we can still get these wet snowfalls that don’t last long, but we’re done with actual snowstorms and cold spells (just barely survived that one). 

That said, a -7 to -8 degree 850mb temp and 500-1000mb thickness around 520 is good enough for sticking snow to sea level if you get the moisture at the right time of day.  And from late Saturday evening through Monday morning, plus again Tuesday, areas up around 1,500′ will score quite a bit.

So the “threat period” for snow in the lowest elevations is late Saturday night through Sunday evening when the moisture runs out.  From 9am-5pm Sunday it’ll be too warm in the lowest elevations too due to the February sunshine unless we get some sort of very heavy showers.

Another thought…here’s the 12z 4km WRF-GFS snowfall forecast from 4pm Saturday to 4pm Sunday.  When I start seeing “fingers” of snow moving out into the valley hills as I see here, that’s when we get very close to sticking snow in the lowest elevations.

 

Chief Meteorologist Mark Nelsen

68 Responses to Snow Outlook For This Weekend

  1. john says:

    so i heard snow levels here in Washington 800-1000ft im about 700ft so i should climb to the top of trees to see something lol

  2. ryan says:

    UPDATED: More and more talk about Valley Floor snow, even a threat through wednesday….

    AREA FORECAST DISCUSSION
    NATIONAL WEATHER SERVICE PORTLAND OR
    228 PM PST FRI FEB 24 2012

    .SYNOPSIS…A COLD FRONT WILL SPREAD RAIN…MOUNTAIN SNOW..AND GUSTY
    WINDS TO THE REGION TONIGHT. MUCH COLDER AIR WILL SETTLE IN BEHIND
    THE FRONT LATE TONIGHT…AND SNOW LEVELS DROP TO NEAR 1000 FEET BY
    SATURDAY MORNING. POST-FRONTAL SHOWERS WILL CONTINUE THROUGH
    SATURDAY EVENING. THE COLD AIR WILL REMAIN IN PLACE AS A WEAKER
    DISTURBANCE MOVES THROUGH SUNDAY…AND LIGHT SNOW ACCUMULATIONS ARE
    POSSIBLE DOWN TO THE VALLEY FLOOR. THERE WILL BE A BREAK IN
    PRECIPITATION MONDAY BEFORE ANOTHER COLD STORM ARRIVES MONDAY NIGHT
    OR TUESDAY.

    A VERY COLD AIRMASS WILL REMAIN PARKED OVER THE AREA AS A SECONDARY
    SHORTWAVE MOVES THROUGH SUNDAY. SHOWERS WILL BE ENHANCED LATE SUNDAY
    MORNING THROUGH AND SUNDAY EVENING WITH THIS DISTURBANCE. SNOW LEVELS
    WILL BE ESPECIALLY LOW…WITH POSSIBLY STICKING SNOW IN THE
    WILLAMETTE VALLEY. IN AREAS WHERE THE SNOW WILL STICK…SNOW AMOUNTS
    WILL BE LOW…LESS THAN AN INCH…WITH BREAKS BETWEEN THE SNOW
    SHOWERS.

    .LONG TERM…MODELS CONTINUE TO SHOW THE UPPER LEVEL PATTERN AS ONE
    OF COOL NORTHWESTERLY FLOW WITH SHORTWAVES MOVING THROUGH THE
    PACIFIC AND PROGRESSIVELY CARVING A TROUGH OVER THE WESTERN U.S.
    DURING THE BEGINNING OF NEXT WEEK. THE GFS…ECMWF AND GEM ARE IN
    GENERAL AGREEMENT WITH THE OVERALL PATTERN AND RELATIVELY CLOSE WITH
    TIMING OF INDIVIDUAL SYSTEMS. A SHORTWAVE RIDGE MOVES ACROSS THE
    PACIFIC NORTHWEST MONDAY NIGHT…THEN A TROUGH DIGS SOUTH OFF THE
    WEST COAST TUESDAY WITH A COLD POOL OF AIR SLIPPING IN OVER THE
    NORTHWEST…AGAIN BRINGING SNOW LEVELS NEAR THE SURFACE WED. ONCE
    AGAIN IT APPEARS THE COLD AIR ARRIVES WITH SHOWERS AND IS QUICKLY
    PUSHED OUT OF THE AREA AGAIN BY A BUILDING UPPER RIDGE. THE GENERAL
    SUMMARY OF THE EXTENDED IS A PROGRESSIVE PATTERN WITH COOL SHOWERY
    WEATHER BEHIND INCOMING SYSTEMS

    • kcteach Gresham 500' says:

      We’ve been through this pattern so many times: watching the radar, coast range eating up showers, and hoping that blob passes over your house. Disappointing in January, but I’ll take what I can get in late February. Maybe we’ll be surprised, but 850 temps less than -10 make it seem improbable. I’ll pay more attention to GOLU.

  3. Kyle says:

    Airplanes and helicoptes have been buzzing all afternoon here which is very unusual for this area where nothing ever happens.

    Airplanes come once in a while like yesterday I saw a guy flying real low over town but that was just a one-time deal.

  4. Wondering why the NAM is always colder?

    • W7ENK says:

      As I recall:

      The NAM was pretty much spot on in November 2010.
      The NAM was pretty much spot on in January 2011.
      The NAM was pretty much spot on in February 2011.
      The NAM was pretty much spot on in January 2012.

      It seems that when it comes to cold anomalies, the NAM’s performance has been pretty stellar in the short range. More-so than the GFS or the Euro.

      Will the NAM be pretty much spot on in February 2012, make it 5 for 5? We shall see…

    • Kyle says:

      How does NAM differ then the GFS?

    • Kyle says:

      Also W7ENK will you post a more detailed review of the NAM during those times please?

    • Mark Nelsen says:

      The NAM was too cold at the surface in January.

  5. Ryan (Walnut Grove) says:

    As with the similar scenario we had this time last year in Vancouver… If you can get a good shower to roll over your area in the evening you could see a decent accumulation that will stick around overnight and melt off in the morning.

    If you get that shower during the day it may be a brief bout of snow and quick melt under 1000′. Alas at this time of year with a strengthening sun you need -10C or colder to get a real snow event in the valleys that can hang around. Otherwise it is brief accumulations at best that melt off quickly.

  6. Just a few pics of some clouds and a corona this morning.

    They are the first 3 pics.

    • W7ENK says:

      You live next to a pyramid?!? O_O

      I wonder if those are high enough to capture sunlight after dark? In the summer, of course… Noctilucent clouds — they have a similar looking structure. Question then becomes, how did they get up there? Typically, they’re blow-off from ultra-high topped thunderstorms, but this time of year? Possibly vapor from entry of some celestial body?? Who knows… It could just be a cloud! :lol:

    • You’re drinking a corona that early in the morning?

  7. One year ago pics from Long Beach:

  8. Sunday lookin pretty chilly Seattle area, couple inches accum on the hilltops eastside look like a good bet

  9. Andrew (Near Silver Falls 1600') says:

    Winter Weather Advisory up for the foothills above 1500′.

    Low of 29 this morning.

  10. OK I’m going to start a poll: snow depth, location, elevation.

    NE Pdx 0″
    Elev. 240′

    There I got it out of the way early.

  11. bgb41 says:

    2/23/2012 Oregon (All) Temperature Summary

    Warmest:
    High:61 at AGNESS2( 247 ft)
    Low: 41 at BROOKINGS(79 ft) & Fremont Bridge W(270 ft) & John Day River B(305 ft) & Rowena(107 ft)

    Coldest:
    High:19 at HOWARD Mt Howard(8150 ft)
    Low: 9 at CRAZYMAN FLAT (6100 ft )

    Largest Diurnal Change: 33 degrees
    DW9301 Klamath F (54/21 ) (4121 ft )
    SELDOM CREEK (50/17) (4875 ft)
    BEND WATERSHED (46/13) (5330 ft)
    CRAZYMAN FLAT (42/9) (6100 ft)

    Heaviest Rainfall:
    0.37″ at Aurora State Air(194ft)

  12. So far in accumulations: this is what i see at this point!

    sea level-200” snowflakes-1”

    300”-500” trace-2”

    600”-1000” 1-3”

    1000”-1500” 3-6

    1500”+ – 6”+

    ++++++POSSIBLE+++++++add an inch or so if u get an extremely heavy shower

  13. Anybody else catch Oregon Field Guide on PBS this evening? Nice segment on the glaciers of the Three Sisters. Using old photos taken over the last 100 years the scientists doing the study were able to document the decline of 40 to 51% of the volume of the glaciers. Matching the climate records (rainfall and temperature) they were able to ascertain that warmer temperatures are the cause of the effect. I climbed the Sisters 34 years ago and remember a rather treacherous terminus at the bottom of Collier Glacier. I wish they would’ve shown that tonite. Guess I’ll have to make another climb and check it out!

  14. Bring on a foot of snow on St. Patrick’s day! I want to shock everyone who says we can’t have big snowstorms after early March!

  15. o.c.paul says:

    great video of navy seals dropping into premier of Act of Valor in LA.
    amazing.

    if video prompts you to open in new window, click on it.

  16. BEn T. says:

    Hey Mark, for Longview at about 270 FT elevation how much would you expect between that time still just a dusting?

  17. PNWweather says:

    A little away from the Portland area again Mark

    Up here in Tacoma I put my snowboard back together again after yesterday’s wind took it apart. I have a much sturdier one now with many more nails in it this time. It will take hurricane to take this one apart.

    I am at 465 feet here in Tacoma and a decent ways from the water. My thinking is much like yours here. Saturday night into Sunday. We’ll see what I end up with if anything. I am not betting the farm on anything significant.

  18. So if ur at 400-500” that means TRACE to 2 Inches possible???

  19. Christian on bull mountain says:

    So it went maybe some snow next weekend, to no snow, to snow this weekend. We will just have to wait and see what happens. I do hope we get a little accumulation at least.

    • Mark Nelsen says:

      I think it just went from big snow and arctic blast to a dusting on the grass (in the lowest elevations). At least in my forecast thinking. The only reason I didn’t make the exact same graphic yesterday was because the cold & snowy weather party needed to be cancelled first.

    • pappoose in scappoose says:

      I really like a dusting on the grass!

    • Mark, if no one sees a snowflake…you can always show them the picture i sent. That way they would at least get to see ONE snowflake :)

  20. 44/31 up here today. Currently mostly clear and 34 with a beautiful sunset.

  21. Back in early December I predicted that I would get 10″ of snow during the month of March. I may or may not, but looking at the models it is certainly a possibility.

  22. Hello old man winter you have reached springs voicemail sorry im unable to take your call but you had your time so please stop teasing us lowlanders!!!!!!!

  23. pappoose in scappoose says:

    Anyone else in for a shallow snowstorm!

    National Weather Service Portland or
    206 PM PST Thursday Feb 23 2012

    Generally…expect cold
    air and snow showers in lower elevations…but no sign of a deep
    significant snow storm at this point. Kelson

    • o.c.paul says:

      Beggars can’t be choosers. But I hope they are very wrong. I want to see TV mets out on freeway ramps explaining how they got snookered.

    • pappoose in scappoose says:

      Always great fun to see those folks out there trying to explain how it’s only going to be a minor inconveince!

  24. Andrew (Portland....Sylvan Highlands ~800 feet) says:

    18z GFS = on and off chances of snow for the west hills and at times below for the entire run. Those are us who are close to 1,000 feet could do quite well.

  25. pappoose in scappoose says:

    May not seem like much to you…but I really like to see snow in the air!

  26. BEn T. says:

    Well, this makes me feel a little more optimistic now.

  27. Steve Pierce says:

    Sorry kids, there will be church Sunday morning! :-)

  28. Laura in Corbett says:

    Sounds like fun to see snow!

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