Interesting Change in Models Today

Of course the 12z GFS run caught my eye…showing the ridge moving just far enough west about a week from now to allow a major surge of cold arctic air into the Pacific Northwest.  It’s the first run of either the GFS or ECMWF to show such a thing, but oh, it is a beautiful sight!  For a reality check I had to head to the ensembles though and I “didn’t like what I found”:

The blue line is the actual GFS you see in the maps (operational run), the red is the average of all the ensembles.  And of course each line with its associated symbol is a unique ensemble member.  Note the operational one; the one we salivate over, is the coldest of them all.  There are several members that show nothing, but the majority do show SOME cooler air leaking south.  Clearly an indication the GFS wants to bring a trough down at least a bit closer to us on it’s way east.  We’ll see what future runs show. 

ECMWF will be finished in about 45 minutes and I’ll post it’s ensemble chart too so we can see if there’s any agreement.

3pm Update:  Here it is:

The 12z ECMWF Ensemble 850mb temp forecast chart has two items to note:

1.  The operational run…the maps we all see, shows no arctic blast of any sort as the Wednesday wave dives down out of Canada well to our east, unlike the GFS shoving it right down over us.  So the blue (operational) line shows no big plunge of cold air…makes sense.

2.  BUT, look at all those ensemble members that must be showing a sharper trough much like the GFS.  You see the huge plunge in temps during the same time the 12z GFS did.  This is where the ensemble forecast information comes in extremely handy.  Operational ECMWF says no cold spell coming, but many of it’s 51 “brothers” have suddenly decided it might happen. 

By the way, the 18z GFS had the cold air much farther east, but a mini blast of cold air at just 12 days away!

Get your model-riding chaps on folks!

Chief Meteorologist Mark Nelsen

226 Responses to Interesting Change in Models Today

  1. Tigard 225' says:

    Watching 00z run is like watching water heat to a boil…

  2. W7ENK says:

    I just got home from the Used Food Outlet in Clackamas… oh my Lordie!! Did someone use the S-word on the news tonight, ’cause people were stocking up and hoarding, practically climbing over one another like the Apocalypse was coming!!! It was a mad frenzy in there, I almost had to abandon my cart and walk out, it was so crazy. I was there the the day before Thanksgiving — which was nothing but a massive, seething cluster-suck of stupid — tonight was by far worse! 😯

    Did someone let the cat out of the bag prematurely, or is it just going to be like this until Christmas?

  3. PDX Weather Nut says:

    Interesting article on extremely high winds in the SW: http://www.weather.com/outlook/weather-news/news/articles/news-west-storm_2011-12-01

    Sure hope we get a snow/wind storm here soon!

  4. 4 hours until 00z GFS!

    Again, watch the run evolve and take it for what its worth. Don’t let it sway your emotions though.

    With that being said of course I am hoping for a cold/snowy run.

  5. alohabb says:

    25 degrees for a low tonight again in Hillsboro? Maybe? Thats cold when your laundry is in your garage and the soap starts to thicken!

  6. Randy says:

    OK, NWS on board for “rain or Snow” in 6-7 day range, NWS curse?

    ORZ006-WAZ039-020645-
    GREATER PORTLAND METRO AREA-GREATER VANCOUVER AREA-
    INCLUDING THE CITIES OF…PORTLAND…FOREST GROVE…BEAVERTON…
    GRESHAM…OREGON CITY…LA CENTER…BATTLEGROUND…VANCOUVER…CAMAS
    222 PM PST THU DEC 1 2011

    .TONIGHT…MOSTLY CLEAR. LOWS 30 TO 35. LIGHT WIND.
    .FRIDAY…PARTLY SUNNY. HIGHS AROUND 45. LIGHT WIND BECOMING NORTH
    5 TO 10 MPH IN THE AFTERNOON.
    .FRIDAY NIGHT…PARTLY CLOUDY. AREAS OF FOG AFTER MIDNIGHT. LOWS
    AROUND 30. NORTH WIND 5 TO 10 MPH.
    .SATURDAY…MOSTLY CLOUDY IN THE MORNING…THEN PARTLY CLOUDY. AREAS
    OF MORNING FOG. HIGHS AROUND 45. NORTH WIND 5 TO 10 MPH.
    .SATURDAY NIGHT…MOSTLY CLEAR. AREAS OF FOG AFTER MIDNIGHT. LOWS
    30 TO 35. NORTHEAST WIND 5 TO 10 MPH.
    .SUNDAY…PARTLY SUNNY. AREAS OF MORNING FOG. HIGHS 45 TO 50.
    .SUNDAY NIGHT…PARTLY CLOUDY. AREAS OF FOG AFTER MIDNIGHT. LOWS
    30 TO 35.
    .MONDAY…PARTLY SUNNY. AREAS OF MORNING FOG. HIGHS 45 TO 50.
    .MONDAY NIGHT…PARTLY CLOUDY. LOWS 30 TO 35.
    .TUESDAY…PARTLY SUNNY WITH A 20 PERCENT CHANCE OF RAIN. HIGHS
    45 TO 50.
    .TUESDAY NIGHT…MOSTLY CLOUDY WITH A 20 PERCENT CHANCE OF RAIN.
    LOWS AROUND 35.
    .WEDNESDAY…MOSTLY CLOUDY WITH A 20 PERCENT CHANCE OF SHOWERS.
    HIGHS 40 TO 45.
    .WEDNESDAY NIGHT…MOSTLY CLOUDY WITH A 20 PERCENT CHANCE OF RAIN
    AND SNOW SHOWERS. LOWS 30 TO 35.
    .THURSDAY…PARTLY SUNNY WITH A 20 PERCENT CHANCE OF RAIN AND SNOW
    SHOWERS. HIGHS 40 TO 45.

  7. Brad says:

    The 12z giveth and the 18z taketh away.

  8. Ben (Beaverton 775 ft.) says:

    WINTER CANCEL!!! WINTER CANCEL!!! 🙂

  9. PaulB/Eugene says:

    I may be a little premature…but out to 102h…looking at N pacific GFS view…18Z…looks to be a home run I think….higher heights ahead of Kamchatka low…..heights a little lower over PDX….vortex deeper over NWT

    • PaulB/Eugene says:

      Maybe not quite….ridge a little farther E this time but cold air still focused toward SW Canada….need to wait a few more frames.

    • PaulB/Eugene says:

      Defitinitely was premature to claim 18Z a good run…not as bad as yesterday’s 18Z…a bit more progressive over central pacific nudging ridge E. On to the 00Z

    • Joshua in Lake Oswego says:

      After reading your first post, I almost prematurely eja…, wait, never mind. Anywho, I look forward to the remainder of your analysis.

    • PaulB/Eugene says:

      Have to be careful when model riding you know….vomit bags are in the pocket in front of you in case you need it.

    • gidrons says:

      Model riding at its finest!!

    • Yeah initially 500mb pattern was promising, but too must westerly energy hammered into the ridge. I don’t take the 18z runs too seriously. 00z runs tonight have more weight to them.

    • Josh (Gresham) says:

      Paul you weren’t the only one… Lol. I was thinking that was going to be really good… It’s not terrible though, still cooler than 6z and yesterday’s 0z

  10. Brian in Bellingham says:

    Portland AFD out:

    “.LONG TERM…OPERATIONAL RUNS OF EXTENDED MODELS IN GENERAL AGREEMENT AMPLIFYING THE FLOW NEXT WEEK…WITH GFS AND ECWMF AGREEING ON MOVING THE RIDGE A LITTLE FURTHER W TO 145W. THIS OPENS
    UP NORTHERLY FLOW FOR A SHOT OF POTENTIALLY COLDER AIR TO DROP DOWN INTO THE REGION. THERE REMAINS SOME QUESTIONS WITH THE MODELS…
    TRACK OF THE COLD AIR AND TIMING. GEM TENDS TO SET UP A MORE WESTERLY FLOW LATE IN THE WEEK…WHILE DETERMINISTIC RUNS OF GFS AND
    ECMWF APPEAR TO LEAN TOWARDS A COLDER TRACK.

    FOR NOW WILL TREND FORECAST TO COOLER WEATHER AND LOWER FREEZING LEVELS BEGINNING MIDWEEK. OF COURSE…THE MORE NORTHERLY THE TRACK THE DRIER ANY SYSTEMS ARE LIKELY TO BE. GIVEN MODEL UNCERTAINTIES…WILL CONTINUE TO INCLUDE SOME LOW POPS FROM TUE ON.

  11. Josh (Gresham) says:

    18z GFS is about to run.. We’ll see.. I’m not expecting much from it, at least not 12z GFS kind of epic.. Lol. But it was a very good sign to see 12z EURO at least trend towards a similar soultion, although not as cold.

  12. I haven’t been available to look at the 12z runs until now. 12z GFS is really nice. 12z EURO is the best EURO run yet too and is fairly similar to GFS.

    We’re getting to the point to where we can watch the block develop in real time with the 12km IR/WV Loop and also the NAM can be helpful now too to see how well that verifies with its projections, which is nice.(and remember, it was upgraded last year) Onto the 18z and 00z tonight to see if model continuity towards a colder trend may be beginning.

    • And it won’t be long before some forecasts and predictions start to fly around here. The emotional ride in real time. So much fun! I better get those Christmas lights up before the blizzard hits 😉

    • W7ENK says:

      I thought the GFS got the upgrade last year… hence why it’s been spitting out the epic cold solution at day 10 since last winter… since the upgrade??

  13. southwindnosnowbobashley says:

    *Clears throat* Mimimimi

  14. Vancouver Dave* says:

    wow,
    just a few days ago the 8-14 was still showing the ridge and dry weather! How fast things can chg. I am putting on the studs earlier than planned…as in today since I am off.

  15. Mat the Salmon Killer says:

    Going to be very exciting watching the models this weekend. We’ll all be like kids in a candy store, even Mark, we all know he’s just as much a weather nerd as all of us, he just has a reputation to live up to. I have a feeling that someday next week we’ll all have a high temp that occurs at midnight and the temp drops throughout the day. I love those days. Those are a good sign that winter is here. Im pullin for ya Mark in that you’ll be the first met in town to start the frenzy. Come on and just mention the possibility today on air and lets see if the other mets follow suit. Anyways, we’d all love to hear your thoughts on this via blog if your not too busy.

  16. PDX Weather Nut says:

    Wow! Hurricane force Santa Ana winds in Southern California. Any thoughts on when our next windstorm coming out of the gorge might arrive?

  17. chiefWright says:

    A question for those that know far more about these models than I:

    What determines the operational member from the ensemble?

    It’s not the average, for good reasons described in this old (2003), but very interesting article:
    http://www.spc.noaa.gov/publications/bright/best-member.pdf

    It goes into quite a bit of detail about how to judge the quality of ensemble members, but I didn’t read it closely enough to find a deterministic answer.

    • Brian in Bellingham says:

      Nobody has replied yet, so I will give it a shot. Hopefully Mr. Nelson can give a better explanation.

      The operational run is THE run, they plug in all of the numbers from around the world, like temperature, barometric pressure, wind speed, jet stream info, etc. And not just surface numbers, but from weather balloons.

      They then hit the “go” button and see what happens. This will be a more detailed forecast (you would use that to see how much rain or snow, etc) then the ensembles. The ensembles are where they run the same model, but adjust the initial input data slightly to account for possible errors. They do not have the detail that the operational has. The point is to see if the ensembles resemble the operational. If the ensemble average and most of the individual members of the ensemble are pretty close to what the operational says, then you can have more confidence in the forecast, meaning even if some of the details in the initial operational run are wrong, there is a good chance the overall forecast will verify.

      But, if the ensemble average and most of the members show something totally different, then you will not have as much confidence. In other words, if just a few details in the operational are off, then the operational forecast can be totally wrong.

    • chiefWright says:

      Thanks, Brian. I appreciate the answer.

      I’m familiar with Monte Carlo simulations where initial conditions are varied, but usually to represent the uncertainty of the measurement of the condition– not uncertainty of the actual condition.

      I’m more familiar with simulations that put variation on the things that can’t be measured– such as actual temperature gradient thruout an airmass, or probabalistic outcomes of chaotic processes.

      Are these variations not considered in the model runs?

  18. Josh (Gresham) says:

    ‎*12z EURO*
    At first glance seems to be trending towards today’s 12z GFS run, in terms of ridge placement, allowing some sort of arctic or modified arctic air to spill into our area around hour 168, much better looking than last night’s 00z EURO.

  19. BLOWMEDOWN says:

    An early peak at ECMWF 12 Is looking much better. For an early peak I use this site. Hope it works for you all. It has lots of pretty colors and easy to understand for the newbies!http://vortex.plymouth.edu/cgi-bin/gen_grbcalc2.cgi?re=namer&id=&zoom=.6&ti=0&ge=800×600&mo=ecmwf&le=850&va=temp&in=4&pl=cf&ft=h168&cu=latest&overlay=yes&mo=ecmwf&le=sfc&va=slp&in=4&pl=ln&ft=h168&cu=latest

  20. 12z GFS definitely gets out of hand with the cold air. At least it’s getting out of hand with it, within 168hrs from now.

  21. W7ENK says:

    A couple questions:

    It seems PDX came close to setting a record for all-time highest barometric pressure this morning of 30.76″ at 4:53 am. I seem to recall about this time last year, maybe it was in January, a fairly static deep low pressure sitting over our area for a few days, no gradients, just low pressure.

    1) Does anyone recall what the lowest BP was back last year during that event? And,

    2) I can’t help but wonder, but what would happen should those two air masses ever encounter one another at close proximity, say, High over Medford and Low over Seattle? Could you even imagine?!? What would the gradient difference be, and how strong would the winds be up the valley???

    Just fantasizing…

  22. Ryan (Walnut Grove) says:

    The only certain thing as of the 12Z runs is model confusion… The only one that really seems hot on an arctic blast is the GFS. Historically the Euro has been the go to model for long range forecasts but it hasn’t been too hot lately either.

    Too many variables so far out; perhaps 72-96 hours from now things will clear up a bit more. Until them I’ll hold onto some hope that we are seeing a progressive shift towards arctic air. I’ll hold my probabilities of it happening to 10% right now. 🙂

    One thing I still don’t like is the flow being out of the south of on shore when moisture is present and the coldest air still not in place. That could keep snow off the valley floor until late Wednesday/Early Thursday if the 12Z scenario where to become reality.

  23. W7ENK says:

    Today marks one week since I first mentioned my feelin’ for cold and snow. Or is it tomorrow? I don’t remember right off hand, but it’s been about a week. At any rate…

    I like this! It’s exciting, and it reminds me of the anticipation of snow I (we all?) endured as a kid, though that was only over night, not 7 to 10 days out… this next week is going to be excruciatingly painful!

    I still think the models will keep pushing the time frame back for another few days before finally releasing it into the close range, then it will materialize into reality. Right now, it looks like next Wednesday late? By Sunday, onset will probably be pushed out to Friday or into the weekend, and come the weekend onset will likely be Tuesday or Wednesday following, but at that point, it will be on it’s way, and for realz! 😆

    That falls right in line (kinda) with my original prediction of Dec. 15-20th. Maybe a day or two earlier? And, don’t forget about the random South wind event immediately before hand… that probably won’t pan out. 😀

    • alohabb says:

      I remeber that video you posted a few years back about the anticipation of snow, the snow, then the travel in that hooptie wagon…man I feel like this year is setting up just like that.

    • W7ENK says:

      That hooptie wagon was tight! Until the radiator hose blew off the back of the engine block… o_O

      Yes, those were good times… I can’t wait to repeat it all over again! Minus the mechanical problems, of course. But hey, it wasn’t MY car, and I wasn’t driving, so… 😆

    • alohabb says:

      I saw a music video that reminded me of this scenario minus the snow…check it out.

  24. SnowedIn - North Plains says:

    Bottomed out at 25F this morning… currently 32.

  25. PaulB/Eugene says:

    Model scan:

    NOGAPS: no
    GEM: no
    GFS ensembles 12z….not really (mean 850 temps at PDX at 180h about -6C)

    • Yes grasshopper.
      One creek flowing high does not make the flood. Two creeks flowing high start to muddy big river. Many creeks flowing high makes big river rise. All creeks flooding make big river flood.

    • Benjamin (West Salem) says:

      -6C is not really an arctic blast, but the ensembles mean is still about 1 degree colder then the mean form yesterday. That is if I’m looking at this right 🙂 IMO Progress???

    • Josh (Gresham) says:

      12z GFS… Off the hook with cold air though..

  26. stevied (North Portland) says:

    WRF-GFS shows…

    Next Wednesday late afternoon and early evening…

    Arctic front moving in with some light valley snow. Pretty colors…

    850mb temps…

    Snow..

  27. Current Denver Weather. Snow, winds North gusting to 21kts, visibility 3/4, RVR (Runway Visual Range) 3,500 feet. That ought to be a fun approach.

  28. bgb41 says:

    Check out the latest 12Z GFSx guidance for Hillsboro. A high temp of 32 next Thursday with 51% chance of precip. That is something to look forward to possibly.

  29. Mark says:

    Models still rolling in, but overall, the future is looking promising (isn’t that always the case!)

    Question: Is the UofW wxloop taking into consideration the terrain? Notice the difficulty the cold airmass is having getting over the canadian rockies. Perhaps terrain data has been added lately to some of the modeling forecast software? Is so, fantastic!

    http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?mm5d1_x_slp+///3

  30. pdxgeologist says:

    I seem to recall that in Dec 2008, Mr. Nelsen stated something to the effect that there was convergence in the models at an unusually early point leading up to the big freeze. They locked in on a solution well ahead of the event and swayed very little. Is my 50 something memory correct?

    • gidrons says:

      My hazy memory says your hazy memory is correct. Models locked onto something cold 10 days out. When it was around 6 days out, Mark put it on his forecast. It is sometimes referred to as the “Train has left the Station” post. If I had more ambition, I’d look it up.

    • Brian in Bellingham says:

      That is correct. They were in remarkable agreement quite a ways out. And I think that was what was so unusual, it was something like 7-10 days before it happened that they were in agreement. Most of the time they “argue” for awhile before agreeing on a solution, whether it ends up being a real arctic outbreak or another false alarm. I expect the models to come to an agreement, one way or another, in another day or two. But I could be wrong.

    • Someone has been taking their Ginkgo Biloba

    • pdxgeologist says:

      Not sure what the wife has been putting in my beer.

    • That depends on the value of your life insurance.

    • gidrons says:

      I got a little ambitious but couldn’t find the post. I think it was earlier than 2008 that the models locked on 10 days out. I did however find a picture of Jessie on the 12/31/07 post. I think some of you have been looking for him.

  31. Oh how we all love the GFS, bigger flip flopper then Romney – didn’t think that was possible.

  32. stevied (North Portland) says:

    text output is fun again..

    PDX -15c and struggling to reach mid 20’s next Thursday

    Pendleton -22c

    http://wxweb.meteostar.com/sample/sample.shtml?text=KPDX

  33. goducks09 says:

    I know it’s been mentioned before, but dang, this anticipated cold snap reminds me so much of early December 2008. Obviously there will likely be two very different outcomes, but the similarities are striking.

  34. PaulB/Eugene says:

    PORTLAND
    KPDX GFSX MOS GUIDANCE 12/01/2011 1200 UTC
    FHR 24 36| 48 60| 72 84| 96 108|120 132|144 156|168 180|192
    FRI 02| SAT 03| SUN 04| MON 05| TUE 06| WED 07| THU 08|FRI CLIMO
    N/X 28 45| 28 46| 28 47| 28 47| 27 48| 37 43| 31 33| 25 36 46
    TMP 32 44| 31 45| 30 46| 31 46| 31 46| 39 41| 33 31| 27
    DPT 28 33| 27 28| 28 28| 26 28| 24 34| 35 33| 28 20| 21
    WND 4 10| 5 5| 5 7| 7 7| 7 7| 10 16| 16 10| 8
    P12 4 13| 6 6| 0 10| 3 0| 12 37| 45 52| 48 40| 28 49 50
    P24 13| 8| 10| 4| 37| 57| 48| 64
    Q12 0 0| 0 0| 0 0| 0 0| 0 0| 0 1| |
    Q24 0| 0| 0| 0| 0| 1| |
    T12 0 0| 0 0| 0 0| 0 0| 0 1| 1 5| 1 1| 0
    T24 | 0 | 0 | 0 | 0 | 1 | 5 | 1
    PZP 3 3| 1 1| 1 1| 5 11| 4 3| 2 0| 2 3| 3
    PSN 19 14| 25 14| 18 7| 9 0| 11 1| 0 24| 43 52| 46
    PRS 5 0| 0 0| 0 0| 4 6| 0 5| 12 7| 5 0| 1
    TYP R R| R R| R R| R R| R R| R R| RS S| S
    SNW 0| 0| 0| 0| 0| 0| |

  35. Dave in SW PDX (235') says:

    Once again, liking the 12z GFS this morning. Next Wednesday could be very interesting.

    Made it down to 30.0° overnight; currently 32.5°, dew point 32°, calm winds, pressure steady @ 30.73″(!)

  36. stevied (North Portland) says:

    Hrs 141-252 on the 12z GFS put PDX at -6c or colder the entire time.

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