12z GFS

A real quick post, only because of one chart I just looked at.  I’ll do a real posting for regular people who don’t need all the technical geekery) later this afternoon.

Here’s the 12z GFS ensemble chart:


A few thoughts:

  • Approaching cold pattern is definitely still ON.
  • Last two runs of GFS have speeded up the timing of the cold front to Sunday midday!  That’s when we go from warm rain to snow showers below 2,000′
  • Based on this chart, the faster movement might not be correct.
  • But based on this chart, all ensemble members are down around -7 by Monday evening anyway, regardless how each run “got there”.
  • The drier arctic front is still timed for Monday night, not as well defined this time.
  • 12z operational, which wasn’t nearly as cold as ECMWF or earlier runs, is one of the warmest members by Tuesday.
  • So it’s quite possible the next run of the GFS will be colder again.
  • A lot of the “noise” has disappeared from Monday and Tuesday, very few warm members now.  Something chilly is going to happen early-mid next week.

As always, I’ll be looking forward to the ECMWF during the next hour.  It just comes out twice a day, which is probably good.  Not as many “mood swings” with either the model or me.

Chief Meteorologist Mark Nelsen

216 Responses to 12z GFS

  1. Goducks09 says:

    Any thoughts on the NAM?

  2. stevied (North Portland) says:

    Well, 06z is the third GFS run in row now that has the Monday system a tad warmer, moves in the chilly dry air, and then gradually warms us up and then some rain with no snow likely in PDX. While 00z EURO was great, can’t ignore this GFS trend. If GFS does this again on 12z and doesn’t show signs of going toward EURO at all, I think I have to pull back on my current “cautiously optimistic” status for any snow in PDX out of this event, even for a transition event on the tail end. Fingers crossed, but can’t ignore this GFS trend.

  3. Kenny says:

    The new 00z GFS shows a 500 foot snow level on Monday with a chance of sticking snow down to sea level if moisture is heavy enough. The best case scenario is an inch of snow down to the floor. After that we get modified arctic air as strong gorge winds show from hour 162 to hour 180. After that there is the resolution change and show east winds dying down but that will not be the case. I suspect that PDX will get a nice overruning event of snow/fleet.freezing rain at the worst as the models never see the gorge influence especially since east of the Cascades will be very cold.

  4. David B. says:

    Beware of “inverse wishcasting.” Getting all pessimistic and insisting it’s going to be a bust just because you feel it in your guts and a few outliers say so is as much wishcasting as insisting the outliers saying there’s going to be cold and snow are going to come true.

  5. Rob - Southeast Portland says:

    00z GFS Ensembles quite a bit better than operational through FCST HR 180.

    The Ensemble isn’t bitter -8c to -12c over PDX, but remember very cold east wind, modified or true arctic air Columbia Basin = PDX always colder than forecast. I learned that many years ago and sometimes the influence it’s significant like 4-8 F colder.

  6. Josh Gardner says:

    Even after 00z GEM/GFS we can see this.

    Highs in the low-mid 30’s with lows in the low-mid 20s followed by an inversion (a cold one at that) with bitter east wind. After that who knows, even if this is the pattern we get its still VERY good by NW standards

  7. Goducks09 says:

    What a waste of an offshore ridge! Luckily winter doesn’t officially start for a few weeks! Plenty more chances folks!

  8. Josh Gardner says:

    I feel like someone needs to get out ahead of this, so I’ll do it. A couple of less than ideal model runs do not denote a pattern change, particularly without any ensemble data. Just as one cannot get too high about a run, one cannot get too low. We’re barely within the 120 hour window, and three days from the 72 hour window, so everyone SLOW DOWN. Otherwise this place will get dysfunctional quick

  9. Jeff Raetz says:

    When the little amount of moisture gets here on Monday it will be cold rain according to the 00z. Then it will be colder and dry. Of course. Time to wait till the 06z comes out

  10. W7ENK says:

    I forecast lots of waterworks in about 90 minutes when the EURO drops a fat steamy coil on the PNW.

    Who’s with me?? 😆

    • Josh Gardner says:

      Why do you enjoy being a troll? Is it fun to constantly be negative. And don’t even give me the realism thing

    • Ben T says:

      Lol Erik, if this blog was all of is in a room. People would be throwing food at you 😉

    • alohabb says:

      I dunno…just because its gonna be frigid cold and little to no moisture(maybe) isn’t really that bad. If you wanna get buried in snow go to the mountain.

    • alohabb says:

      That’s the tough part about blogging, you cant tell the tone about a comment and unless you know whos writing, sometimes people take them the wrong way. Just my 2 .

    • flurball says:

      You seem to have changed your ideas. A couple years ago you seemed to be out of a job and open to things and now you are just bitter and sending pictures from across the river with a good sunrise where you work. A big deal about Milwaukie not getting weather you don’t
      approve of.

    • runtmc says:

      It will get worse before it gets better. He’s even been known to quote himself on occasion. And poor emoticons–What did they ever do to him?

    • W7ENK says:

      And I’m the troll? Nothing out of you Josh for weeks, perhaps months, and your last 4 posts today have been direct jabs at me, and completely lacking in weather related content. Keep it up, and Mark is going to catch on to what you’re really doing here…

      Preparation H, kiddo. Simmer.

    • Josh Gardner says:

      Naa, Mark see’s all the posting I do over on the Facebook group thats not for overgrown children. But I’m done interacting with you. It’s a losing effort

    • JJ78259 says:

      I am with you man the dome will be in effect as I arrive Monday Morning back to Portland for a visit. No lowland snow for the city!

  11. Kenny says:

    The new 00z Canadian Model gives PDX sticking snow down to sea level this coming Monday as a small surface low forms and makes landfall on the central Oregon coast.

  12. Rob - Southeast Portland says:

    00z GFS wasn’t very good. Glancing blow. 00z GEM colder, but looks like a brief shot, then more cold air to our east as the ridge migrates towards the Coast.

    • Those Canadians know a little something about cold air, so maybe the GEM is on to something, eh? But yeah, what a letdown after this morning’s 12z extended WRF-GFS run… I suppose there’s still a chance the 00z extended will give us some hope.

    • Rob - Southeast Portland says:

      00z GFS Still a good modified blast via Gorge, so it could be colder than what is shown thanks it pulling arctic air from Columbia Basin.. Very strong east wind.

    • Rob - Southeast Portland says:

      Looking at 850/925mb for Columbia Basin shows a high likelihood of a prolonged Cold Pool.

    • Rob - Southeast Portland says:

      It will be colder in PDX than what you think. The Dalles is progged for highs in the low to mid 20’s, with very strong cold east wind PDX will be several degrees colder than forecast (right now)

  13. stevied (North Portland) says:

    Some low snow levels, probably no accumulation in PDX, and then dry chilly east wind with a very gradual warmup. Well, definitely not as exciting as runs over the past day or so.

  14. blowmedown says:

    Omg!!! 00z is not very good people, but may flip back to our favor I have seen it before. Its going to be cooler than norm but nothing epic this run so far! Most going to our east and a bit north of us so far this run! Grrrr!

  15. BoringOregon says:

    Man you guys are so dramatic about the weather oh my :)…..

  16. marcustheweathernut says:

    00z gfs is blah so far…..

  17. marcustheweathernut says:

    Does anyone know when our first 80 degree day is on average?????? : )

  18. 1980: 4 minutes left in this hockey match and we are up one point over the Soviet All-Stars. Can we pull it off? Will this be epic?

    2001: A 15 point lead with 10 1/2 minutes to play, only a major meltdown can keep the Portland Trail Blazers from reaching the NBA Finals.

    I hate all this time on the clock…

  19. JohnD says:

    I am a lifelong W. Oregonian, weather enthusiast, occasional blogger, mostly lurker type person.
    Lots of compelling stuff going on and that is for sure.
    Given the general concert of the models, I think that we would mostly all agree that SOMETHING intriguing weather wise is likely to occur within the coming days (weekend-beyond.)
    But-as always-“the devil is in the details” (which is why we are all glued to this blog!)

    E.g. Will the ensuing pattern end up a wimpy garden variety cold snap–with initial moisture outrunning the cold air followed by cool/cold conditions for a day or two and then a mild moist Pacific system which quickly pushes it all away?–which appears to be TV met Matt Zaffino’s current take–(and which I find a bit odd because he is typically one of the ones with superseding “event passion”.)

    OR will it be something FAR more epic/dramatic (which is what most of us in this forum are all pulling for!!!) and DOES seem possible!

    Or–more likely–something in between!

    The NOAA people seem to be fairly bullish–although they, too, seem to be in a rather conservative mode. I do find it interesting that they are under billing our imminent event as likely being one that produces “the coldest air of the season”! Never mind the fact that if it Is anything like the last few years it may well be the ONLY cold air of the season!

    ‘Can’t wait for Mark’s next post. He really is good and doesn’t pull punches.

    Anyway, here’s hoping with you all for an optimal outcome. Nothing like a winter wonderland event in an area that rarely gets them! AND furthermore the 55 Portland snowplows-sanders are getting rusty! It has been a while!

  20. W7ENK says:

    Oops! Looks like Monday’s low veers off into the Dakotas.

    That’s not good. 😦

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