Strong System For Sunday and Long Range Thoughts

Some interesting twists and turns on models and maps the past 24 hours, probably the first time this season we’ve seen the possibility of strong wind here in the Valleys show up.  The key word is POSSIBILITY in that sentence.

The area of interest is later Saturday night or early Sunday morning.  Various runs of various models show some sort of surface low deepening and moving very quickly SW to NE somewhere across the Pacific Northwest.  If you want a good windstorm west of the Cascades, you want something like what showed up on the 00z GEM (Canadian) model LAST NIGHT:

A deep low making landfall around Astoria and tracking quickly east or northeast.  When that happens we get a great rush of wind from the south and southwest behind it; a classic windstorm.  And you want the isobars perpendicular to the valley so the wind can rush straight south to north.

In the past 24 hours other models have had the low much weaker, or farther south, or moving through as an open wave (weaker than a closed low), and now a couple don’t even show a consolidated low, but more of a double structure.   This evening the GFS, WRF-GFS, and GEM are showing the open wave or double-type structure.  That would imply nothing too exciting.


There is no good model consensus as of this evening what’s going to happen; but those 3 models might be a trend developing for a weaker wave that just gives us more rain and breezy conditions only.   We may get a strong surge of wind later Saturday night or very early Sunday morning OR just normal breezy conditions and no one will even notice.  As we say in this business; we’ll see what the next run of models holds.


Some chatter today about possible colder weather showing up on the maps.  I have several thoughts on that, especially for the newbies out there:

  • #1  You shouldn’t get excited about anything beyond 6-8 days unless it consistently shows up on most or all models.  That means run after run of similar results.  That did happen just before the 2008 cold spell; day after day of models showing a major change.  Otherwise you’re getting yourself worked up over nothing; and it sure isn’t worth arguing about
  • #2  We have 4 runs per day of the GFS that go out to 16 days, 2 runs of the ECMWF that go to 10 days, 1 run of the GEM that goes out to 10 days.  Plus a few other models.  There will be something “coldish”,  “near snowy/snowy”, or even an “arctic blast”  on ONE of those models almost every day between now and February.  Another reason to not get too excited unless #1 (above) occurs.
  • #3  Ignore the surface temps on the IGES output after about Day 3.  They’ll lead you astray; often extremely cold for the pattern.  Just keep an eye on 850mb temps, surface wind (Southerly or Westerly = Bad for Cold/Snow), and actually look at the maps instead of just reading text output.

That said, I don’t see anything too interesting in the next 7-10 days.  Cool troughs Sunday/Monday and again next Wednesday/Thursday will keep highs in the 40s then and maybe snow down around 2,000′ with that 2nd trough.  If so, that’ll be just about the lowest so far this season.  Here’s the 850mb ensemble chart from the 12z ECMWF:

Note the cold trough later next week with pretty good agreement on 850 mb temps down around -4 to -5.  Then most members seem to get a little milder but a WIDE variation (thus the “spaghetti plot” name).  Note a few members of the 51 members show -6 to -9 850mb temps in the 10-15 day range.

A few of you may have noticed my blogging frequency is down a bit the past couple of weeks.  I’m doing all 5 evening shows while Stephanie is gone (she’ll be back in two weeks).  Not much room in the workday for anything other than getting graphics put together, emails etc…  Luckily for me (but not for you) most of this Fall the weather has been relatively slow.

Chief Meteorologist Mark Nelsen

56 Responses to Strong System For Sunday and Long Range Thoughts

  1. Jake says:

    Lets hope we get a frost free December-March. When is the next 80 degree day on the map?

  2. paulbeugene says:

    Look what I found from Philadephia (look at the bottom of the post…wouldn’t that be cool.

    Click to access WinterAnalogs2012to2013.pdf

    • W7ENK says:

      Whoa, that really threw me for a loop! The color scale on the top map is inverted from the rest of them, so at first glance I couldn’t figure out how the monthly breakdowns all showed us significantly cooler than average, but the composite had us ungodly warm…

      Why’d they do that???

    • Brutally cold January and cold February for Washington/Oregon, if I’m looking at it right?

    • paulbeugene says:

      Keep in mind…the dark blue was more the 3F below normal…that is the 1981-2010 mean temps…which we all know overall are warmer than the past by a bit…I guess I am just having 1919 on the brain

    • W7ENK says:

      Ohhhhhhhhh… that’s precip. 😦

      So, cold but dry then…

      Well, I guess that means that what little precip we do get during the D-J-F timeframe should come in frozen form, right???

    • Brian in Bellingham says:

      W7ENK, the composite that you think is warm is actually the precipitation composite. Which would be really dry. And that is consistent with very cold temps.

    • W7ENK says:

      Yup, I discovered that.

  3. paulbeugene says:

    Looks like we will have to just watch the satellite imagery (particularly the water vapor loop) for a “surprise” low forming off of NoCal in the next 24 hours. Wind event looks less likely than was apparent a day ago.

    As for precipitation…looks like 2-3 inches on valley floor (liquid of course) in next five days. The three day period ending December 6 looks like a good one for the ski areas…with 12-18 inches plus at pass elevation (snow)…perhaps 2-3 feet at the ski areas. Beyond that point..anyone’s guess…seasonably changeable weather without extremes.

    It should be mentioned that this is the second November in a row that is has been 10F below normal for the month in Fairbanks. That is no shabby accomplishment. Must be the partly due to the PDO but have not had the time to do the research. In general it cannot be extremely cold here and extremely cold in Alaska at the same time.

    Long range models (I am talking about ensembles..not operational runs)…the general trend is for rising heights over the Gulf of AK or off the west coast of USA… instead of being much below normal…it gets to normal if not above normal. What I have not seen from any ensemble means is a positive 500mb height anomaly over interior Alaska. Without that…it plain simply won’t be cold here…..even if 500mb heights are somewhat below normal over our region….just cool maritime air which at this time of the year gets to look more and more like snow at pass elevation.

    Last year, we had that dreaded dry period from end of November to mid December. This year it won’t be the same situation, at least in the next 2-3 weeks. It looks to me that interior AK will continue to be in the relative ice box for another couple weeks. I say relative because it has not been extremely cold there (yes it did get down to -52F in Chicken yesterday)…just consistently cold . I think the ski areas should end up looking pretty good come winter break.

  4. I’m surprised no one has posted this yet. I can’t be the only one who really likes today’s 12z ECMWF
    Great 500mb progression

  5. runrain says:

    Very windy in Happy Valley, strongest in some time. Where is this coming from?

  6. JohnD says:

    I climbed Mt. Shasta with my daughter and 2 friends
    this past June 28–humbling–grueling–joyful–in near perfect conditions. Cold in the a.m. and breezy at the top though and snowpack all the way. It didn’t take much imagination to envision at the summit what the weather must often be like there during the winter. Simply amazing.

  7. runrain says:

    Want excitement? NWS expects the top of Mt. Shasta to receive 110 inches of snow and 115mph winds the next few days. If only…

  8. Overall pattern looks good for building a snow pack and getting the ski areas rolling at full speed in the next couple weeks.

  9. 12z GFS 500mb
    Day 10(FCST HR 240)

    • It’s nice for awhile, and then it sucks after. We can’t even get la-la land to be nice to us. Jeez

    • Danny in Troutdale says:

      I haz sad 😥

    • Brian in Bellingham says:

      I tried to post this before, so hopefully this won’t be a double post.

      Rob, I posted this at Western. You will get a good laugh over it. This is what happens when you model ride.

      I am not making any predictions, people who know far more about weather then I do make predictions and are wrong all the time, so this is not a prediction of any arctic outbreaks. The truth is we don’t know what is going to happen.

      I give you some quotes from December 1, 2008 from my fellow weenies.

      “December and February will obviously suck”
      “Wow there’s a pretty strong signal that at least the majority of December will be warm”
      “That sure doesn’t bode too well for this December does it? Good stuff though. I guess we can look forward to January maybe!”
      “Another brutal model run……..”
      “You got my hopes up until I actually looked. Not much there out through 276. edit: now that I see the whole thing it’s a piece of crap.”
      ” No, it’s actually a whole lot warmer and drier. If the 00z verifies then there will be weenie suicides left and right. Pretty much warm, dry, and ridgy through the middle of December with no valley rain or mountain snow in sight, and certainly no cold.”
      “What happened to the Arctic cold and snow from the 10th on??????????????????”
      “Overall the pattern the last 3 months has predominantly been warm and dry, and that looks to continue right on through the beginning of the heart of our cold season”
      “It’s amazing how quick the models have changed. At this rate, December will probably be another horrible month.”
      “I would not be suprized if this pattern lasted clear into Mid January or later. It really would not”

    • runrain says:

      Time to move to Denver!

    • @Brian, long time no post… I wonder how many of those were from Snow Wizard or Tim?… 😆

  10. I just looked at 6z NAM/GFS, 12z NAM/GFS including hi-res MM5(WRF still running, but looks weak and pathetic with wave development). They have removed any chance of a south wind event/storm for late Saturday night – Sunday. They either bring in a weak low south of us, or an even weaker wave into extreme southern Oregon/northern California. Unless something drastically changes with the 12z ECMWF or 00z runs tonight you can stick the proverbial weather fork in this idea.

    I suppose it is time to root for la-la land and look towards the slight possibility of cold/arctic air down the road. Now, to be fair 6z GFS was kind of close to being really nice. 500mb pattern progresses pretty good with a ridge nosing up offshore, but it seems transitory in that it never became established evolving into a block. I guess you can say baby steps. 12z GFS running now out to FCST HR 162. Hoping to see signs of improvement near FCST HR 180.

    It seems we are literally destined for boring weather anymore. Oh well, may as well bring on another east wind event/storm.

    • Doesn’t surprise me that the wind storm threat disappeared. Wouldn’t surprise me if it reappeared. I just don’t think these type of features show up on the models very far in advance. Just too localized. IMHO

  11. alohabb says:

    Hmmmm, a good windstorm for us is usually one that we don’t forecast or watch on models for a week out aka SouthValley Suprise. This is kinda setting up to be just like that,

  12. Kirk(Sandpoint Idaho) says:

    Great post Mark.

  13. karlbonner1982 says:

    Here’s a question: What do you think is the warmest 850mb temps over PORTLAND that could realistically lead to significant river-level snow in the GORGE? Let’s assume some coolish air over the Columbia Basin but no serious arctic airmass.

  14. bgb41 says:

    11/29/2012 Oregon (All) Temperature Summary

    High:62 at BANDON( 79 ft)
    Low: 52 at Tillamook Airpor(36 ft) & DW1265 Newport(164 ft) & Florence Municip(52 ft)

    High:30 at WASCO BUTTE(2272 ft)
    Low: 22 at NYSSA (2172 ft )

    Largest Diurnal Change: 34 degrees
    CW5615 Heppner (59/25 ) (2041 ft )

    Heaviest Rainfall:
    4.61″ at ILLINOIS VALLEY(1389ft)
    4.09″ at QUAIL PRAIRIE LO(3183ft)

  15. SnowedIn - North Plains says:

    This is what I gathered from Mark’s post.

  16. W7ENK says:

    All I need is 0.74″ of rain before midnight tomorrow night to reach the 10.00″ mark for November. Think tomorrow will bring the goods???

    • longbeachrob says:

      Lucky me I have 11.18 inches as of right now. I think in this game I would rather I was less than you.

    • bgb41 says:

      I think your rain gauge is not calibrated correctly Erik. It has not rained that heavy this month in the dome.

    • W7ENK says:

      I actually have two rain gauges, one digital and one analog, and they’re less than a foot apart. They’re attached to a platform about 16″ squared that’s supposed to double as a snow board, though I’ve barely had occasion to use it as such since I built it. It’s up at eye level, and about 20 feet out from the house with clear overhead. I always average any disparity between the two, but they’re almost always within 0.04″ of each other, which is the unit measurement of the digital gauge. I’m not sure how to calibrate a plastic analog wedge.

      I’m sorry if anyone thinks my readings are off, but it is what it is.

      0.15″ overnight.

    • Ron says:

      I’m between Oregon City and Estacada on the edge of the foothills, sitting at 7.11″ so far for the month.

    • W7ENK says:


      KORMILWA6 Logus-Stanley (Milwaukie)
      Range 0.50 miles at 228.0 degrees

      KORPORTL172 Portland Rowing Club (Portland)
      Range 2.56 miles at 295.5 degrees

      KORPORTL111 Oakgrove PO 1E (Milwaukie)
      Range 2.54 miles at 354.0 degrees

      KORPORTL110 52nd – Woodstock (Portland)
      Range 2.31 miles at 4.0 degrees

      Looks like my 9.41″ is in the ballpark for my area, boys. I’ll provide a breakdown of each day’s precip when I get home this evening.

      If you wanna have some real fun, you could easily use those points to triangulate my station’s precise location to within a few yards. Feel free to drive by and inspect my raingauges for yourself, I just ask that you don’t steal them, please. However, I can’t guarantee that I or my neighbors won’t call the police if you’re spotted tromping around in my yard. :mrgreen:

  17. karlbonner1982 says:

    Do you REALLY think the Gorge will warm up to the mid and upper 40s tomorrow, Mark? You realize that it takes trapped cold surface air to drive the east wind – so if The Dalles warms up to 46 or 48 we SHOULD completely lose the east wind in Troutdale.

  18. vernonia1 says:

    anyone heard anything about an earthquake in OR this eve??

  19. We’re all in for a surprise come 12z or 00z tomorrow….

  20. Scott Houdek says:

    but then again those models could be wrong.

  21. Mark Nelsen says:

    Paul just posted the Canadian ensembles here:

    I’d like to put in an order for ensemble #3 or #16 please. Can we make it a meal and add a post-wind snowstorm for $1.65?

    • It looks like 5 members would give PDX a wind event/storm. #16 would be very damaging.

    • Mat the Salmon Killer says:

      Mark, dont forget about #18. I’ll do an add on of wings for .99 for that one too.

    • longbeachrob says:

      Anyone want to point me in the direction of a text book so I can figure out more what is going on? Or even a link would be good. I don’t understand yet what relation all the smaller images below the larger one mean. I did study Physics a long time ago, so I don’t mind math etc…

    • EY (Oak Grove) says:

      As far as I know, the smaller images are just different outputs from the model, with the larger one being the mean/average. I could be massively wrong, but I THINK that’s what it all means.

      I’m going to order ensemble 4 and have a side salad of disappointment.

  22. W7ENK says:

    And the plot thickens…

  23. paulbeugene says:


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