Cold Air Is Here…Freezing Rain Threat Decreases

The chilly air has moved in…we are 31 at 9pm in Portland compared to 46 just 24 hours ago! East wind is just starting up in the Gorge and that wind will arrive after sunrise for most of us.

As a result of clear skies, low relative humidity, and light wind, temperatures are dropping quickly. We’ll end up around 20 in the coldest parts of the metro area and 20s everywhere else. Not quite as cold as two weeks ago, but close.

No changes in tomorrow’s forecast with sunshine, a gusty east wind, and chilly temps.

But Monday is sure looking different as of this evening’s model runs.  The last three model runs have been suppressing the precipitation farther south, decreasing the intensity, and slowing it down.   If current runs are correct, much of the day could be dry in the metro area and/or rain will fall with temperatures above freezing.  Take a look at our RPM 7am Monday:

MarkRPM_Cloud_Snow_Fcst and 11am with precipitation just arriving.MarkRPM_Cloud_Snow_Fcst2 That’s too late to get freezing rain with marginal temps and a dying east wind.  The reason the east wind dies off more quickly this time around is because the northern stream of the jet is sending a weather disturbance east across southern British Columbia and Washington.  Flow from the WNW up at 700mb and higher tends to form lee-side troughing on the east side of the Cascades.  This always happens and in this case high pressure weakens quickly over the Columbia Basin on Monday.  Pressure gradient is down to just 2-4 millibars easterly by Monday evening through the Gorge.  So one more reason it won’t be too hard to warm it up above freezing Monday morning.

So does this mean no freezing rain Monday?  No, but the chance of it occurring has dropped quite a bit.  Of course tomorrow’s model runs could bring the rain farther north again, but the trend is usually your friend and the trend since 12z has been to keep it farther south.

By the way, the last 24 hours was a little bit of a disappointment up on the mountain.  At least to me.  I was hoping we could over-achieve and get a foot or more.  Timberline and Meadows had 8-10″ and Skibowl 6″,  But we need a lot more and I don’t see that coming.  Mt. Bachelor is the only ski area in the state that has been able to offer several lifts for Thanksgiving Weekend skiing.  You can see why; they have more than two feet on the ground.  I don’t see a significant snow storm for Mt. Hood in the next 3-4 days at least so next weekend MAY not be much better.


Chief Meteorologist Mark Nelsen

52 Responses to Cold Air Is Here…Freezing Rain Threat Decreases

  1. Boydo3 N. Albany elev. just under 500' says:

    OK, I just noticed the snow flakes on the blog.

  2. paulbeugene says:

    It is also showing precip type as rain rather than freezing rain. With dewpoint temperature in south valley in upper 20s at this time, not sure that there will be freezing precipitation here. I’m guessing that NWS is exercising at least a due amount of caution given that the freezing rain event a couple weeks ago was sort of under forecasted, due to concerns about impending blizzard in and around the gorge/east metro.

  3. alohabb says:

    Carefully driving in shaded areas today! Still slippery. Single car MVA on Farmington and Clark Hill….Life Flight called.

  4. WEATHERDAN says:

    As of December 15 NWS PDX is shortening their forecasts on nws weather radio to just the first 4 forecast periods. That is to say 48 hours. So if a bi honking snowstorm is 4 days away the nws won’t mention it on the weather radio. Their reason is that some people have complained of it being to long a cycle. Usually under 4 minutes. However you can still call them up and talk to them live and get the extended forecast. And since they appear to have a lot of spare time I guess they would rather have 1,000 people a day calling them up to find out the extended outlook or the forecast out to 3 days than listen to it on the weather radio. So when you call them press the # key and you can talk to them live, get your information and help relieve their boredom. Peace

  5. paulbeugene says:

    Worth a mention that the latest HRRR run shows precipitation all the way N to PDX, not heavy but at least something. Would not count PDX out of the freezing rain fest

  6. alohabb says:

    Hmmmmm……freezing rain advisory now for Mac And South Valley.

  7. CFS blowtorches the whole country in December. At least the first half of the month looks like a fairly good bet to be a coast to coast torch.

  8. Got down to 24 up here last night. Chilly, but not as cold as a couple weeks ago when I had 3 nights in a row with lows in the teens. Currently temp up to 34 under sunny skies. My dusting of snow is hanging tough in the shade….

  9. paulbeugene says:

    I have not made any comments lately on prospects for skiing (on snow that is).
    We are entering a neutral to positive EPO pattern, a positive PNA pattern, with persistent negative 500mb anomalies well W of California, S of Gulf of Alaska.

    Having looked at the CFS, Euro weekly ensembles, GFS ensembles, it appears that any meaningful accumulating snow in the Cascades (pass elevation) may have to wait until mid to late December (guessing Dec 15-20).

    Timberline will be able to run Flood and Molly’s lifts by Dec 18.
    Ski Bowl won’t open til Dec 22.

    Frankly, that would not be all that bad. Getting snow earlier and then having a rainout at the ski areas come Christmas/New Years would not be ideal.

  10. paulbeugene says:

    4km WRF model soundings show only a thin layer of cold air in the Eugene area, less than 500 feet thick, during the first hours of rain tomorrow morning. Looks quite marginal for freezing rain.

  11. Sapo says:

    Well, MM5-NAM and WRF-GFS latest runs still looking terrible for precip Monday, GFS bad, I haven’t seen a model that actually shows a freezing rain threat here in Portland…But the NWS discussion says that “TWO OF THE MAIN MODELS KEEP THE MOISTURE SOUTH OF THE
    Which model is showing the moisture reaching us?

    • The NWS’s wishcasting model 😉 j/k
      I’m guessing maybe the GEM since both the GFS and Euro took it away?

    • Boydo3 N. Albany elev. just under 500' says:

      Freezing rain sucks anyway. We got hit a couple of weeks ago and there was thousands of dollars worth of damage to trees and property in my neighborhood alone. Don’t like it 😦

    • Sapo says:

      Ya, I think the model showing that is the GEM, it looks like the model shoving the most precipitation over us, it shows some potential for freezing rain.

  12. W7ENK says:

    Never would have thought I’d need to move my avocado into storage twice… in NOVEMBER!!

    • David B. says:

      I’ve lived in the PNW for nearly 25 years and I don’t remember two arctic blasts in November ever. Even one is unusual for this month. Usually they happen in December or January.

      On a possibly encouraging note is this from Seattle Weather Blog:

      Don’t know how well that rule holds for PDX, though I’d guess that if there’s really such a correlation it should hold region-wide.

      Yes, yes: I know: Portland missed out on the snow from this one. But Seattle missed out on it during the first blast. So both regions have already seen some snow in November (we didn’t get much this time, either; just a dusting in most areas).

      • Mark Nelsen says:

        Portland also didn’t really see an “arctic blast”. High temp 35-40 isn’t that cold. Yes, a cold Canadian airmass, but down here it’s not like the high temp was 25-30 degrees. Just my opinion of course.

    • paulbeugene says:

      There have been 8 Novembers at PDX Airport station with measurable snow. Average snow for the remainder of the winter (Dec onward) is 5.88 inches. There has never been a November at airport where there was not any measurable snow after a November snow event. 1977 was the worst, with only 0.1 inch of snow during the winter afterward.

  13. David B. says:

    23 this morning after an overnight low of 21.

    • David B. says:

      Arlington (WA) bottomed out at 12 last night. Outflow winds kept the Bellingham area mostly in the mid/upper teens overnight.

  14. SW says:

    I wonder how well todays EURO would have done with the winters of 49, and 68?

  15. pappoose in scappoose says:

    11/30/20147:00 AM
    Temperature15 °F
    Humidity89 %
    Wind Speed9 mph
    Wind DirectionESE

  16. Tyler Mode says:

    Just picked up a light NE wind now.

  17. Tyler Mode says:

    22 this morning here in Battle Ground.

    Had fog develop briefly around midnight. It was enough to leave everything rather white.

  18. Muxpux (Castle Rock 175') says:

    The front passing overhead with a nice squall and a 7 degree drop in about 8 minutes was exciting here.

  19. se pdx jon says:

    Maaaan. It snowed earlier. So bmmd. Can’t wait for the main event

  20. vinnybob says:

    Please… I don’t want another 1976-77. Most boring winter that I can recall.

  21. Jason Hougak says:

    One thing we need is more arctic air to kill the mountain pine beetle destroying our western forests. The beetle prefers pine species and spruce which we don’t have naturally on the Cascade west slope and the coast but east side and into the Rockies, especially BC and Canada are getting slammed. The beetle is destroying entire forests. I worked for a customer who grew up in Colorado and he went back last summer. He said it’s sickening. There are places where entire mountains are dead. Drought stress the lodgepole pine the primary host tree and mild winters allow for a greater amount of beetles to survive. Without cold winters and healthy trees our forests will be destroyed. Checkout the epidemic, pine beetle pictures Colorado.

  22. schmit44 says:

    11/29/2014 Oregon (All) Temperature Summary

    High:59 at LAKE OWHEE AND O(2400 ft)
    Low: 47 at Brookings Airpor(459 ft)

    High:22 at Timberline Lodge(7001 ft)
    Low: 4 at HOWARD Mt Howard (8150 ft )

    Largest Diurnal Change: 41 degrees
    DW9612 Umapine (55/14 ) (797 ft )

    Heaviest Rainfall:
    0.92″ at Brookings Airpor(459ft)

  23. JohnD says:

    Yep, 1 down 3 to go for the late fall-winter months. Nov. has been interesting–more so than many years. Still disappointing when considering the disparity of some C + E Oregon record Nov. cold stats vs. those iin PDX. I honestly can’t recall that much disparity. Normally when C Oregon is well below zero, Portland would do better than low 30’s– as was the case a week or do ago. Mtn. snow packs, of course, are struggling too. Lot’s of time to go; but we do need to get going…

  24. Jason Hougak says:

    So Mark, what are your thoughts of this pattern repeating itself the rest of the winter? Warm, cold, warm, cold. I wouldn’t mind as long as a skiable base develops… Sure was nice working those mild days. Worked today too and loved it as ” WELL!”

    • Mark Nelsen says:

      We sure don’t want this splitty/ridge pattern to continue or the ski season will be as bad as last year. We haven’t had a cool/wet pattern in the Cascades so far this month.

    • Jason Hougak says:

      No I agree. We need a deep cold pool in the Gulf, an active jet, and a NW flow to develop and hold. That’s a winter.

  25. Brian Leroy says:

    Death ridge in long rang models, winter canceled oh well there’s always next year, good night.

  26. Jason Hougak says:

    Still a ways out but the ECMWF develops a cold pool in the gulf.
    Got a quick inch of snow about 2:30, warm ground temps and marginal air temps melted most by the time freezing temps hit. Just nice to have sum snow.

  27. Jorge Chavez says:


  28. dharmabum says:

    Time to start scoping out the long legged models.

  29. Eugene Dave says:

    Oh well. Time to start scoping the long range models.

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