Coldest Weather Of Winter Coming Up, For Some

We don’t have any sort of big arctic blast on the way, but a much cooler feel to our daily life here in the metro area.

Here are the highlights:

  • November & December have been very mild.  In fact we’re likely to see December 2012 go down as the warmest December since 1999.
  • A colder air mass has pushed through the Columbia River Gorge and into the metro area this evening.  It’ll be over us and turn a bit colder next week.
  • High temperatures will only be 40-45 even with sunshine (that sun begins Sunday) tomorrow through next week.
  • Low temperatures in calm parts of the metro area will drop as low as the upper teens and lower 20s beginning New Year’s morning.
  • Everyone will finally have a hard freeze.
  • Cold east winds will be around for a long period, Monday through Friday next week at least.
  • The bonus?  Little to no rain in the next 7-10 days and ample sunshine.
  • The Coast and foothills/mountains will not be unusually cold, quite a bit of sun in those areas too.

For the hard-core weather folks…

Take a look at NOAA’s snowcover map for today west of the Cascades:

nsm_depth_2012122805_Northwest

and eastside:

nsm_depth_2012122805_Intermountains

It doesn’t show the very lowest elevations east of the Cascades as snow-free (they are), such as The Dalles and areas right along the Columbia River, but there is definitely snow cover across just about the entire rest of the Columbia Basin.  Snow cover is very good at reflecting the warming rays of the sun, and allows rapid overnight cooling under clear skies.  That’s a setup for a pool of cold air to form and stay trapped in the lowest 3-4,000′ of the atmosphere east of the Cascades the next few days.  A bit cooler than we have seen in previous east wind events the past few years.  It’ll happen because we are now in “split-flow” over the West Coast as very weak upper-level systems fall apart as they move towards us.  With no stronger systems to mix out the cold air, it’ll stay put.  Cold air is dense and heavy, so pressures rise eastside.  There’s no place for the cold air to move except through gaps in the Cascades below 3,000′.  The only one lower than that between British Columbia and California is the Columbia River Gorge.  Thus a cold east wind blows through the Gorge and accelerates down the western end.

This evening the effect of the cooler east wind and drier/colder air mass has shown up in several ways.  It’s ten degrees colder at Biddle Butte just across from Vista House at 1400′.  Last night it was 36 at that spot at 9pm, tonight it’s 26.  That’s not because of calm and clear conditions either since the wind is blowing hard up there.  Ausperger Mtn (3,000′) east of Carson is 10 degrees colder at 9pm as well.  31 last night but 21 tonight!  Dewpoints have taken a dramatic tumble in the metro area too.  PDX is 28 right now, it was 37-39 at the same time last night.  Much drier air is now over us and will stay here through next week.

A weak system comes down from the northwest tomorrow afternoon, but at best it’ll produce a few sprinkles.  Another one attempts to move into the ridge and splits apart late next Wednesday or Thursday.  The 00z GFS and 00z GEM both show it producing precipitation (rain or freezing rain most likely) at that time.  We’ll see.  Future runs may show it just dry.

I expect clearing, dry air, and not too strong of an east wind away from the Gorge next week.  This is the perfect setup for much colder overnight temps.  I could easily see the 18-22 degree range at Hillsboro and Scappoose.  Even PDX could get well down into the 20s if the wind backs off at that location at night.

For those of you in the west end of the Gorge, fire up the wood stoves!  Looks like a long period of strong east wind and very cold temps.  Highs only in the 30-35 degree range much of next week in the windy areas.

Chief Meteorologist Mark Nelsen

77 Responses to Coldest Weather Of Winter Coming Up, For Some

  1. KPTV Tower Temps
    As of 2 PM (1 hour lag. Updates every :15 after the hour)
    Upper Sensor(1818′) 31.5 (32.2 at 1:00 PM) Lowest: 30.0 12:15 PM
    Middle Sensor(1473′) 32.0 (33.3 at 1:00 PM) Lowest: 28.2 10:00 AM
    Lower Sensor(1043′) 35.1 (35.6 at 1:00 PM) Lowest: 29.3 7:55 AM
    http://www.wrh.noaa.gov/pqr/tower_temps/tower_temps.php?&units=F

    • 00z(4 PM) Upper Air Analysis(Observed over PDX)
      925mb: -0.3c
      850mb: -3.5c
      700mb: -12.2c
      500mb: -27.6c

    • Marcus says:

      Looks like there is a batch of showers holding together just south of Tacoma area would be cool to get a little dusting of unexpected snow tonight!:)

    • Ben T says:

      They look like they are holding together but going more to the east and past us.

    • Marcus says:

      There is another batch just nw of Seattle, that may if it holds together come over us it’s a little more west. But is showing signs of falling apart because it is tracking right over the Olympic mountains.

  2. A few things to discuss

    * Snow? *
    Flurries or even a few periods of light snow this evening? Maybe.

    IR Loop shows a shortwave over extreme SW British Columbia probably over Bellingham by now dropping south. Note the enhancement seen along and west of the Washington Cascades…
    http://www.atmos.washington.edu/images/ir4km/201212292330.gif

    Radar shows this nicely too.
    http://www.wunderground.com/radar/radblast.asp?zoommode=pan&prevzoom=zoom&num=6&frame=0&delay=15&scale=0.591&noclutter=0&ID=RTX&type=N0R&showstorms=0&lat=0&lon=0&label=you&map.x=400&map.y=240&centerx=290&centery=329&showlabels=1&rainsnow=1&lightning=0&lerror=20&num_stns_min=2&num_stns_max=9999&avg_off=9999&smooth=1
    Nice batch of rain/show showers to the north moving south in Lewis County and approaching Cowlitz County. This may hold together into Clark County. Temps in the upper 30′s may fall slightly, but relatively low dewpoint values with any precip falling into drier air mass in place could allow for weak evaporative cooling. Just something to keep an eye on.

    East wind storm coming? I think so. I would circle 10 PM Tuesday Night – Noon Wednesday. It looks like to me at least a 10mb PDX-DLS gradient, probably stronger. A strong cold pool over the Columbia Basin and eastern Gorge with 925mb temps -7c into the eastern Gorge meanwhile there is warmer air aloft surging northward with 850mb temps over PDX up to +8c. That combined with the strong gradient should really squeeze the winds dramatically further through the Gorge in my opinion. Question is, how strong? East of I-205 50-60mph probably. Another question is, will this be mainly a gap event, or also downslope through Clark County? Unsure.

    As far as the Arctic Blast shown on la-la land on the GFS. I like the prospects. My thinking is we have this splitty flow for 7-10 days, then that goes away with an initial rather flat ridge offshore axis 130-135W which retrogrades to the west and amplifies around January 9th – 11th. We’ll see, eh? ….

  3. lilfoot123 says:

    41 & ice pellets Kelso/Longview! If the roads stay wet could be icy in the am

  4. pbo9 says:

    Light snow flurries in north Portland. Ended now. 39ºF.

  5. Ben T says:

    How far south is the precipitation on the radar going to come?

  6. J-Kelso says:

    Rain and sleet here temp 39.4

  7. chris s says:

    @ Erik, here are the pics i took at the airshow of the funnel cloud in 1993.

    IMG]http://i47.tinypic.com/3143qza.jpg[/IMG]
    [IMG]http://i46.tinypic.com/k2bv2t.jpg[/IMG]

    • W7ENK says:

      Wow, nice pics! Yup, that’s about how I remember it, but I dont think I was it come so close to the ground like that, it almost looks like it touched down…

      Thanks for uploading! Would you mind if I download those and add them to my archives?

    • Chris s says:

      Sure, no problem go right ahead.:-)

  8. thomyee says:

    Snow flurries in portland heights at 500 feet.

  9. Muxpux (Castle Rock 175') says:

    Workin up in Olympia, had a light freeze this AM, now getting some light rain showers

  10. Due to the reports of Snow Flurries in the area the National Weather Service has just issued this! I grabbed the audio version of the statement. Here it is…..

    http://www.divshare.com/download/21431750-6c9
    Click ‘ l> PLAY ‘ … Be safe everyone!

  11. PDX Weather Nut says:

    I sure wish we’d get some snow in town. I’ve been looking often at my pictures from December of 08 which was the last decent snow PDX had.

  12. pbo9 says:

    This is the perfect set up for gardens. Mild freezes will harden plants off and make them less susceptible to any truly arctic air that we might get later. Whew! We needed this. My Olive trees will be happy.

  13. geo says:

    Snow flurries here in sw Gresham !

  14. 12z WRF Analysis

    00z WRF last night showed we were supposed to lose the east wind today as offshore flow ceased around 1 PM today. My analysis last night disagreed with this. 12z WRF today shows we might lose the east wind for 4-8 hours if that as the gradient goes flat or very weakly onshore. I’m not sure at this point that the PDX-DLS truly ever goes onshore(or a +positive reading). Also, WRF is showing a tighter gradient now with a peak PDX-DLS -10 to -12mb. That sounds about right.

    Cold pool looks about the same with -9c 925mb temps over the Columbia Basin, but now is even showing -8c or so over the eastern Gorge. It looks every bit as cold as 00z last night. We may lose the east wind January 4th as a weakening 1010mb low just off the Oregon Coast swings northeast moving onto the central Washington Coast, but hints of the cold pool regenerating by Saturday morning Jan 5th. I’ll look at Soundings and other stuff to give ideas about any precip, or if it’s Snow/Zr…..

    I just ran the WRF 3hr Precip model and BONE dry through at least 10:00 January 5th. The biggest difference I see on this run is probably found on the Cross Section now showing 40kts down to 975mb. Quite a shallow east wind field. Look for the infamous ’50kt wind barb’ showing up I bet soon. Also, the end of the cross section there’s the east wind returning as the cold pool regenerates as I mentioned above. http://www.atmos.washington.edu/mm5rt/data/2012122900/images_d2/kpdx.x.th.gif

    12km Sounding shows increasing Temp/Dewpoint spreads and possible moisture Thursday, January 3rd, which I’m really skeptical about. If it did occur the Sounding is too warm for Snow/ZR…. Hunch is Sounding may turn colder in future runs. Basically get set for dry weather with possible east wind storm east of I-205.

  15. ocpaul says:

    I kid you not, very light snow flurries in Oregon City.

  16. W7ENK says:

    Dropped to 29.8F this morning, my first freeze since April 7th. My yard was all white and frosty looking until about a half hour ago.

  17. 27.6 last night, lowest of the year so far.

  18. PDX Weather Nut says:

    Glad to finally get the first freeze! About a month overdue.

  19. Joshua in Lake Oswego says:

    30.2 here. First freeze finally!

  20. mothernature007 says:

    How do I post a picture in here? I have a question but would like to show the picture with it.

  21. runrain says:

    Mid 50′s San Antonio today. Riverwalk here is beautiful. Go Beavs!

  22. Tyler Mode in Battle Ground says:

    28 here this morning in BG. Coldest of the season so far.

  23. eugene in vancouver says:

    Down to 28.7 now in west vancouver, first freeze of the year!

  24. Ben T says:

    Hundreds gather to protest global warming. 👉http://i.imgur.com/PkNjH.jpg I think you guys will appreciate this.

  25. Yeah…

    33.6, Dewpoint 25, gust east wind 25mph… In fact, for a PDX-DLS of only -3.1mb this has to be hands down be the strongest winds I’ve seen for that kind of gradient. Precursor of much higher winds in the days ahead? Could be.

  26. Ben T says:

    Had a walk with my dad around the lake. It definitely feels chilly outside!

  27. Sifton says:

    This will be a great test coming up this week; What do I hate more…………rain or cold?? ‘Liking’ this winter so far (minus snow) & only 60 days left!!!

  28. bgb41 says:

    12/28/2012 Oregon (All) Temperature Summary

    Warmest:
    High:49 at Port Orford( 0 ft)
    Low: 43 at Port Orford(0 ft)

    Coldest:
    High:15 at HEREFORD(3599 ft)
    Low: -11 at RED BUTTE (4460 ft )

    Largest Diurnal Change: 38 degrees
    RED BUTTE (27/-11 ) (4460 ft )

    Heaviest Rainfall:
    0.31″ at HEBOWX Mt. Hebo(3160ft)

  29. Mat the Salmon Killer says:

    Redmond, 23.4, 17dp, 78%. Gonna be a cold one the next week. 12 this morning. Brrr

  30. bgb41 says:

    NWS still calling for a low temp of 33 for the whole upcoming week. I guess they are going to blow another one.

  31. We may be seeing weak systems approaching us, but check out the monster on WV Loop developing well offshore near 39.5 N, 161.8 W.
    http://www.atmos.washington.edu/images/wv_enhanced/201212290630.gif

    00z NCEP/NWS Pacific Surface Analysis projects to be around 985mb now, but bombing rapidly down to 959mb near 48 N, 152 W.
    http://www.opc.ncep.noaa.gov/P_sfc_full_ocean.jpg
    I think it may be deeper than that. Too bad this low wasn’t further west as the ridge it pumps up ahead of it could have put us into a more favorable 500mb flow for colder/arctic northerly blasts. IF COULD WOULD MIGHT SHOULD MAYBE

  32. paulbeugene says:

    GFS 00Z MOS extended guidance has EUG getting to 19 to start the New Year (PDX to 21 New Year’s Eve)….if that materializes that is a decent fake cold air mass.

  33. Temp/Dewpoint/Wind Thread

    33.8, 27, E @ 25.4

  34. What’re you thinking of for high/low temps for The Dalles, Mark?

    I’d say 29-35 the next few days with lows probably getting down to 18-25.

  35. Longview - 400 ft says:

    Well. . . I guess I should go get the hoses in and cover the water faucets now that freezing temps will be the norm next week.

    I will enjoy this though!!!

  36. W7ENK says:

    Mmm’kay…

    • W7ENK says:

      I guess I’ll spend tomorrow clearing out my storage to make way for ny avocado tree. Anything below 26 will kill it. Last winter, my temperature dropped TO 26, twice, and the leaves on the upper 2 feet burned off. After 6 years now, I don’t want to lose it!

    • W7ENK says:

      I just checked, my temperature is at 34.9, DP 23… YIKES!!

  37. Thanks for the update, Mark. Your thoughts are very much in line with my previous analysis. This cold pool has trended colder and colder. I too won’t be surprised if areas east of I-205 struggle to reach 35.

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