Spaghetti-Like Maps

Here’s a nice image that displays the challenges of the long term forecast.  It’s the various GFS ensemble members for Tuesday, December 8th (D+8 forecast).  A bit of confusion eh?

Okay, back at it this evening.  I just perused the 00z maps to compare with the last 24 hours.  There had been quite a bit of excitement with various models (Canadian and GFS) showing arctic air intrusions into the Pacific Northwest at differing time periods.  Of course each model run has been different.  Notice the spaghetti chart is a huge mess from the 12z GFS.    That’s unusually messy for Day 8.  Now the 00z models are in and I don’t see any sign of a big blast of cold air;  that’s due to models showing the upper level ridge staying quite close to the Coast.  What I do see is classic El Nino conditions.  High pressure nearby, a wet southerly jet across the USA, and cool offshore flow for more than half the 7 day forecast here in the Pacific Northwest.  Since the first week of December is just around the corner, any offshore flow will keep us chilly.  It’s tough to get high temps above about 52 at PDX with easterly flow December through January.  More likely in the 45-50 degree range later next week.  Add to that overnight lows down in the 20s in outlying areas and it’s going to really feel like December around here as we progress through the next 7-10 days.

Chief Meteorologist Mark Nelsen

344 Responses to Spaghetti-Like Maps

  1. Andy in Woodinville says:

    Think someone on here mentioned about an over running event shown on the long range. Was kinda going for same idea as it looks like flow slowly switches around to southerly and 10m temps slowly rise above 0c and 850mb temps also rising to near freezing by end of 384hrs. So for it`s worth, we have a COLD/ DRY shot of air with possible highs in the 20`s, lows in the teens to single digits as 850mb temps fall to about -18c with yet another blast a few days later that gives Seattle and surround places like the east side Puget sound area of nearly a foot of snow in 12/24hrs. On top that, a possible over running of event of some sort. WHOA!

  2. Rob "Wrath" S.E. Portland says:

    0z EURO in 2 hours 14 minutes!!!!!!

  3. PaulB/Eugene says:

    If GFS is right, we will need to wrap those pipes. I would guess that would translate to highs in 26-34 range…lows in 15-24 range….considering that there would not be much if any snow with this…temps would not bottom out at night as much as they could…then again it is much too early to get crazy with specifics…having an arctic blast with ridge at 140W position a bit too iffy…in other words, the much more likely outcome in that instance would be for cold air mass to head E of the Rockies…..we need that ridge to set up shop a bit farther W…then again then you run into potential problem of cold air dumping over Q Charlottes, digging trough offshore for cold rain here….you cannot always win.

  4. Tyler in Hazel Dell says:

    Any precip is about 2 weeks out on the models…that’s a long time!

  5. Andy in Woodinville says:

    Thats right Rob, I said SNOW :):)

  6. Mixer Mixing Mixed Yevgeniy Mixed Mixing Mixer says:

    all i have to say is WOW

  7. Jesse-Orchards says:

    Wow, 00Z has 850s around -17C by hour 180.

    That would buy us a high in the lower 20s or so on Monday.

  8. Andy in Woodinville says:


    ANOTHER SURGE of cold, but this time MOIST AIR with N-NW flow with thicknesses of 510-516m over Western Wa and 850mb temps of nearly -10c. Adding to this is….SNOW! Yes, thats right, I said snow. 10m temps drop to -10c with 12/24hr totals over Seattle area showing nearly a foot of snow in a 12/24hr period. Exciting!

  9. Rob "Wrath" S.E. Portland says:


    Wholly pancakes!

  10. Tyler in Hazel Dell says:

    In terms of snow, remember models don’t pick up well on storms that spin up as the cold air moves offshore…however, like mentioned here before, I don’t see a lot of undercutting systems like last year…that brought us all the snow.

  11. Timmy - Scappoose says:

    over-riding system by day 9-10

  12. Andy in Woodinville says:

    Should also mention that there is some mid level moisture for the weekend(during time frames shown), but it`s east of the Cascades and pretty much stays east as it sinks south with the developing area of low pressure also sinking southward.

  13. Tyler in Hazel Dell says:

    Btw, wouldn’t a 850 temp of -13 be right around freezing at sea level? I know adiabatic warming is about 3 degrees per 1,000′, so Gov Camp is around 4,000′, 4×3 would warm us to right around -1 Celsius at the surface.

    • Timmy - Scappoose says:

      its hard to tell, we should be able to stay below freezing with about -10c over the dalles with a decent east winds. The gorge is our friend. but i think for the mid-south valley about -13c sounds about right.

    • Jesse-Orchards says:

      It would if the atmosphere were stagnant, but during setups like this we obviously get a lot of cold air advection through the gorge, from areas with even colder upper level airmasses. So we’d actually be colder than you’d think with that formula.

      850s of -13C with a stiff east wind would give us highs in the mid-upper 20s in the Portland area, I’d guess.

  14. Jesse-Orchards says:

    850mb temps at -12 by hour 156 of the 00Z. I like.

    This is looking like a classic true upper air arctic blast setup. If the models keep this up, it could end up being our best since December 1998.

    Wouldn’t it be great if the models just lead right up to this thing from here on out, with little in the way of big run to run changes? I guess I can dream…

    • Tyler in Hazel Dell says:

      It would fall in line with what happened last year…and that was unprecedented I think!

    • Rob "Wrath" S.E. Portland says:

      Yes! It would be great. Well hey models nail last years historic pattern 7-8days out. This also looks like a real prolific downslope wind event/storm type arctic frontal passage with high pressure building rapidly to our E-NE.

    • Jesse-Orchards says:

      Perhaps the models are getting better. Stands to reason as computers get better, I guess.

  15. Tyler in Hazel Dell says:

    510 thickness over Portland around 10 am Sunday…

    850 temps at -13 about?

  16. Andy in Woodinville says:

    Still looking pretty darn COLD for the weekend as 00zGFS continues to show thicknesses down to near 510m come around Sun and flow turning more Easterly with 850mb temps dropping to about -12c. With COLD/DRY air in place, could still see highs in the 30`s with lows in possibly the single digits to teens. But that of course could all very well change!

  17. Rob "Wrath" S.E. Portland says:

    Down to 37.2 F

  18. Timmy - Scappoose says:

    out to 162, 00z is more aggressive with the arctic front so far

    • Rob "Wrath" S.E. Portland says:

      Yeah things look pretty good. Perhaps a few features are a TAD further east, but not much.

    • Jesse-Orchards says:

      The ones that matter aren’t further east. The heart of cold air actually migrates slightly further west on this run.

    • Rob "Wrath" S.E. Portland says:

      I had only seen it to 108-120hr when I posted. WOW the retrogression is very evident…. BITTERLY cold.

  19. Tyler in Hazel Dell says:

    I see nothing bad for cold in the 0z. 516 thickness is over PDX at 06 Sunday…that is the demarcation (in general) for snow at PDX. Granted, it is dry, but still. That is hour 150 on the GFS, definitely believable.

    • ghcshweather says:

      Yep, everything still looks on track for the first arctic intrusion of the season, hopefully as it gets closer the models will start showing a little more moisture.

    • Ben Randall says:

      are you looking at the Washington atmospheric web page

  20. Tyler in Hazel Dell says:

    Warmness is the mid-level clouds moving in right now, my temp is up 5 degrees in the last hour and a half.

  21. ghcshweather says:

    It is all about the placement of the ridge, and its looking just a touch further east on the 00Z than earlier runs, overall everything we need is there and we won’t know for sure for 3-4 days minimum on how cold it is gonna get.

    • Jesse-Orchards says:

      Dude, the 00Z is way better for cold than the 18Z.

    • ghcshweather says:

      Dude, nowhere in my post did I say it was worse than the 18Z, geez!! All I mentioned was the the HP area looked a touch further east, nothing about being warmer than other runs.

  22. Ben Randall says:

    00Z model looks like it keeps us dry through the first part of December

  23. Andy in Woodinville says:

    GFS out to 132hr right now and looks good so far with E-NE flow at the surface/850mb.

  24. Snow-Zone/Monmouth-Elv200' says:

    Cooling a lot faster than last night. 33.1F currently.

  25. PaulB/Eugene says:

    00z looks good to 108h…the anchor trough in central pacific at or just w of previous model run

  26. Tyler in Hazel Dell says:

    537 at 0 UTC Saturday, vs 545 on the 18z.

  27. Tyler in Hazel Dell says:

    18z had us at 553 thickness at 06 Friday…0z has us around 546 from what I can see.

    So this punch from the NW seems to be coming in a bit earlier.

    Still loading…

  28. Andy in Woodinville says:

    Shawn, the models have been back and forth with the idea of cold and snow/ cool & dry/ seasonable & dry or mild and wet. Well really, they`ve been all over. So wouldn`t place bets on the models just yet. 🙂

    • Shawn in Salem says:

      Thank you Andy,

      I didnt realise at first I was repsonding to a post Mark had apparently put on yesterday. Im not sure that he will actually find time to read mine and respond to it.

      Obviously I am brand new to this blog but I will figure it out.



  29. Shawn in Salem says:


    I have been an amateur all my life and really enjoy your forecasts. Of all the meteorologists we have on the local tv stations, you have the best handle on the difficult task of forecastoing our weather.

    I have a Davis Inst Vantage Pro2 station I purchased recently to replace the Vantage Pro I had for about 10 years. I live in the hills of South Salem at about 600 feet and was wondering if I can put it to use for you in any way? Weather spotter or any other possible use?

    Please let me know.

    PS.. We love snow and was dissapointed to hear the possibility of colder weather next weekend seems less likely now with the new models that just came out


  30. Andy in Woodinville says:

    Hey Tyler, I see your on here. Do you know whats up with WesternWx? It`s been down since last night. 😦

  31. Tyler in Hazel Dell says:

    And the 0z begins…

  32. Snow-Zone/Monmouth-Elv200' says:


  33. Andy in Woodinville says:

    18z Ensemble charts aren`t great, but A FEW dose try to send some for of cooler air over us for the coming weekend.

  34. JacobPSE-BPA says:

    Hello all Mallow is correct with that but Remember a couple of things with a Arctic front very dry limited Moisture you need some development of some sort sliding down the coast
    Maybe a dusting with a front coming down from the North
    but there has been a couple of things that bode well
    Duration and the Great Polar Vortex
    Andy keeps talking about this and VERY COLD TEMPS I will share thoughts later after we have our morning meeting

  35. Since current weather is somewhat boring, the latest “Storm Chasers” has been good on the Discovery Channel…


  36. Snow-Zone/Monmouth-Elv200' says:


  37. Andy in Woodinville says:

    Folks! The 18z is much colder!:) For the upcoming weekend, the GFS is still locked on to a…lets say sub arctic intrusion of much colder air than what previous runs showed. Air mass still looks pretty dry with due easterly flow at the surface/850mb with moderate pressure gradients. By around Sun into Mon following week, 850mb temps falling to about -18c with 10m temps falling near -10c and thicknesses falling to little below 510m. So up here in the Puget sound region would say areas away from large bodies of water and outlying places could see highs in the low 30`s with lows in the single digits to lower teens.

    Should also mention that 12zWRF shows near -10c temps at 925mb for Sun afternoon. And for the GFS is worth, this cold, dry air could possibly last into much of next following weekend before we return to normally cool conditions.

    1pm sun.

    Looks like 12zEURO is in agreement to some degree with the GFS as the EURO drops a cold area of low pressure over for Sun/Mon, but then quickly goes to zonal flow in the extended. And in looking at the 12zGEM/ Canadian model, they to are in agreement with some sort of cold trough over us for the coming weekend. While it`s good to see some agreement, we`ll have to see what tonights 00zGFS shows.

  38. Andy in Woodinville says:

    Hey Rob, just now getting home from work, and unfortunately WesternWx is down yet again and has been down since yesterday evening! :o(

  39. goducks09 (Oatfield, OR) says:

    Just for kicks, this is what “MallowTheCloud” mentioned over at concerning the 18z…maybe jumping the gun, but still interesting…

    “If the 18z verified at 500mb, I would expect the Arctic front to have more moisture associated with it, as the trough itself extends offshore. That upper level vorticity along with the baroclinic boundary formed where the Arctic air meets the Pacific maritime air should be enough to spin up a weak low at the west end of the “front,” stalling it and throwing moisture into the equation.

    This will only work if the 500mb trough can dig “far enough” offshore, though.”

    Thoughts? Or is it too early for those? 😉

  40. snowman says:

    could someone please tell me whats the good site to check out those computer models. and hey what are our chances really of that cold air here? i mean the arctic stuff!

  41. Snow-Zone/Monmouth-Elv200' says:

    I am surprised accuweather has not forecasted any snow or cold weather yet. All they have for my location is temps in the upper 40s and 50s. I was at least expecting there forecast to be highs in the 20s with a couple of big snow storms coming through starting on the 5th and on through the end of their 15 day forecast…. Oh well their not reliable anyways.

    • Beaverton Chris says:

      AccuWeather did have next week as being pretty cold, with highs in the lower to mid 30s all of next week, starting next Sunday. They even had snow once or twice during that time. That forecast only lasted a day, however, and changed to what we are seeing now. You’re right that they aren’t very reliable.

  42. goducks09 (Oatfield, OR) says:

    Just a side note/thought…
    One think to maybe keep an eye on is the Hudson Low that is poised to drive much of the arctic express into the northern plains next weekend/early next week. I know its called a Hudson Low for a reason, but if we can get it to strengthen closer to 100w (further west of Hudson’s Bay, it could drop that bitterly cold air closer to the Rockies & PacNW. (Just day dreamin’ now) 🙂

  43. muxpux says:

    anyone else on here a part of CoCoRaHS?

    i was looking at joining it, sounds kinda fun, like your “doing your part”. not just measuring for bragging rights, but reporting for something useful…

    anyways, they have a rainguage for 25 bucks, is it possible to find one cheaper than that? one that would still work?

  44. goducks09 (Oatfield, OR) says:

    Just for giggles, this is a quote from Mark’s post on December 1st 2008 “December Starts Warm”…

    “…For the rest of us, the clear message on the short and long range weather maps is slow, slow, slow and boring, boring, boring. More fog, sun, and occasional east wind. The first ten days of December are going to be uneventful. But we can always hope that the arctic blast of the decade is just 5 days after that right?…”

    Very eerie to say the least. If we had only known what was ahead. LOL

    • Rob "Wrath" S.E. Portland says:

      Wow no kidding!

    • goducks09 (Oatfield, OR) says:

      Back then you were “Dr. Rob -Far S.E. Portland”, LOL! My how times have changed.

    • Rob "Wrath" S.E. Portland says:

      LOL Yeah or Atmospheric Wrath.

      I also remember,
      Storm Commie
      Fox12 Blog Snowman Mascot
      Gradient Keeper
      WV Loop King

      I’m sure there are others…

    • Timmy_Supercell (Hillsboro) says:

      I wasn’t into the whole Fox 12 bit until early this year. Wish I was watching his forecasts. TWC still was pretty accurate, on a few of those big snow days, they mentioned between 1-3 inches for portland. Many people around here said the snow event wasn’t forecasted well, but as far as I can see, a lot of meteorologists saw it coming days in advance.

    • Timmy_Supercell (Hillsboro) says:

      Rob, don’t forget “Droppin!”

    • Rob "Wrath" S.E. Portland says:

      Oh jeez how did I forget that one? LOL That’s my DJ name.

      Thanks, Timmy. 😀

    • Timmy_Supercell (Hillsboro) says:

      I’ve been thinking about making some changes with my name here, not sure what it will be though.

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