Monthly ECMWF Run

The monthly run of the ECMWF model was sure interesting today.  Here are the ensemble means of 500mb heights averaged for each of the next 4 weeks.

We already know what’s happening in the next week…warm and wet:


Then when it appears the cooler troughing offshore with moisture starts aiming cold systems at us the end of next week?  We go right into a split-flow pattern with the upper-level high building just to our north.


Check out the control run at 400 hours…about 17 days from now.  ecmwf_17dayanom  Sure looks like the terrible winter (for skiing) of 2004-2005!  Troughs and precipitation moving by mainly to our south in a southern stream of the jet.  The weekly average during that period looks like this.


About this point is where it gets interesting.  Here’s the last weekly average showing a similar setup too:


The control run shows two times where the upper level high is slightly farther to the west, allowing a push of cold arctic air down east of the Cascades and the Intermountain region, much like what we saw in mid November.  The first is around Christmas and then a week or so later.  I’d put the maps online but they are from WeatherBell and their latest policy is NO redistribution of ECMWF data, so I’m trying to cut back (sneaked one in there).

What does all this generally mean for the next few weeks?

1. Warm rains next week.  Most of next week the snow level will be above 5,000′.  Much of that time it’ll be above 6,000.  But we’ll see lots of 50-60 degree high temps in Portland too…October is coming back!

2. Turning much drier about 10 days from now, with below normal rainfall after that time.

3.  Ski areas COULD have a real rough time getting lots of slopes open as we head into Christmas Break.  BUT, as you know, just two good cold storms that sneak through and drop 12-18″ could get things going…pray for that.

4.  Around Christmas and beyond we could get real chilly again with strong east wind.  Not a big surprise that time of year of course.  In that forecast pattern and in the depth of Northwest winter, the cold would stick around for quite awhile too.

5.  Just having the upper level high to our north with wet systems going by to the south increases the likelihood of overrunning events (freezing rain) in the Gorge and possibly metro area as well.  We’ve already seen that several times (right now) and it’s only December 4th!

Of course all of this speculation is based on 1 MODEL RUN of ONE MODEL…but it’s fun isn’t it?

Chief Meteorologist Mark Nelsen

46 Responses to Monthly ECMWF Run

  1. Mark says:

    I know this isn’t weather related – well, the animal is native, and it does enjoy our weather – so with that, Go Ducks!

    Sorry Mark, but your alma mater’s hay day was when you were going to school there.

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

    Anybody see any cold air or even a 5000′ freezing level in our future?

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

      To answer my own question it’s looking a bit more promising next weekend

  3. runrain says:

    Quick, Erik. Catch that sunrise. Beautiful!!

  4. schmit44 says:

    12/4/2014 Oregon (All) Temperature Summary

    High:64 at ILLINOIS VALLEY(1389 ft)
    Low: 58 at Gold Beach (US 1(60 ft)

    High:28 at MIDDLE MTN(2544 ft) & EW3690 Dufur 9e(2444 ft) & WASCO BUTTE(2272 ft)
    Low: 20 at EW4395 Milton Fr (3455 ft ) & Blue Box Pass (U (4024 ft )

    Largest Diurnal Change: 24 degrees
    Worden (54/30 ) (4080 ft )
    EW4395 Milton Fr (44/20) (3455 ft)

    Heaviest Rainfall:
    1.90″ at NORTH FORK(3120ft)
    1.71″ at DUNES(120ft)
    1.66″ at GOODWIN PEAK(1800ft)
    1.60″ at EW1814 Florence(98ft)
    1.59″ at EW4831 Portland(425ft)
    1.58″ at EW1914 Portland(151ft)

  5. Well, now that we’re into the first week of December it is time to play this game again…. Whammies = Split flow, Cold Rain, or Pineapple Express/AR Events. NO WHAMMIES! NO WHAMMIES! OH, and check out this tidbit of info! I created this: Tuesday, December 09, 2008, 1:47:31 PM. WE ALL KNOW WHAT HAPPENED NEXT!

    • High Desert Mat says:

      What your missing Rob is an unprecedented east wind event. After all, that is your call sign.

    • High Desert Mat says:

      And what your saying is we have a 22.5% chance of getting split flow or cold rain? I would give it that percentage if we were actually in the winter of 08′. But for now I give it that chance later this month like Mark said.

      Yes Mark, we’re all holding it to you now. If your wrong we’ll all know why you don’t give winter forecasts at the winter weather meeting at omsi every year or any other time.

    • David B. says:

      Michael Larson where are you now that we really need you?

    • Rex says:

      LOL! That was epic Rob. Nice work. Now, where is Peter Tomarken when you need him?….

  6. High Desert Mat says:

    Well I can honestly say now the Mets here dont know anything. It was suppose to be above freezing come Monday and no more wintry precip. Its now Thursday and the temp barely got above freezing here in Redmond today and now back to 28 with more zr earlier tonight and everything a big mess. Longest spell of zr I can remember at least since I lived on NE 20th and Couch St. In Portland in late 03′ and early 04′. Go winter of 14′-15′!!!!

  7. High Desert Mat says:

    Funny how Mark tries to keep the blog alive after all this boring we have coming up. Way to go buddy lol. In a week and a half this blog thread will all but be forgotten. But most of us wont forget, right guys? I know I won’t. Thanks for the info Mark, we all appreciate all you do here really.

  8. You mean WeatherBell doesn’t want geeks to share important weather maps with the public???


  9. Chris s says:

    00z gfs shows about 7 inches of rain starting in about 10 days mark, as have the past few days of gfs runs… So that is quite at odds with the euro at this point us it not?

  10. JohnD says:

    Least we can say, a cold, rainy day today in Portland, Oregon indeed. And if you like lowland winter weather–and most of us, apparently, do there is reason for,optimism longer term….

  11. dharmabum says:

    Fake cold?…pray?…..not impressed?….praying?….dreaded?….thinking models?…(actually I like that one, artificial intelligence!)

    Reality check please

  12. David B. says:

    Cold in late December, eh? Cue Bing Crosby:

  13. What is the chance of a bunch of Columbia Basin “fake” cold air throughout December? Will the stormtrack to the south be enough to mix things up this way or are we looking at something like what happened mid-January last year?

  14. The KING of Weather Spreadsheets says:


    Do I dare ask what the GFS is saying for the same period out that far? Oh wait, I never trust the GFS so never mind and don’t waste your time on that. 🙂

    I did look at the CPC 1 month and 3 month precip and temp maps the other day and I must say I am not impressed for our region. I did see one chart today that puts the El Nino temps up to +1.5 C on it’s ensemble forecast. Not an all time record El Nino but one that would be noticeable.

    Anyway the precipitation seems to continue mainly down in the Southern tier of states for the next three months while as a whole we dry out over the same period. In other words the three month map is very Nino looking and right now the pattern seems to be trending that was as we see it here today.

    Shannon O’Donnell up here at KOMO agreed with me last night on my thoughts of an El Nino emerging.

  15. Tyler Mode says:

    Usually the ECMWF is great with general patterns. But, it totally missed the cold spell in November.

    However, it seems more of the models are thinking cold the last week of December.

  16. Jason Hougak says:

    I’m praying that the GFS pans out better in the long run, both show the cold pool hitting us.

  17. Jason Hougak says:

    I’ve been saying, winter of the dreaded freezing rain… 😟

  18. dharmabum says:

    Sounds like typical Oregon winter weather.

  19. Sapo says:

    And thank you for posting these maps! Very helpful. That would be great to see us getting really cold just in time for Christmas. With this kind of pattern, do we usually just see overrunning freezing rain/snow events or is it possible we could see a snowstorm when it stays cold for awhile? For example like last year in Feb.?

  20. Jason Hougak says:


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