Cold Front Signals Big Weather Change

A nice cold front has been moving through the Metro area the past hour.  We often don’t see a signficant change as a cold front passes here in the Pacific Northwest.  The “weather waters are muddied” a bit due to the modifying effects of the mild Pacific Ocean.  But this time around we’ve seen a sharp shift in wind from south to northwest (gust to 33 mph at PDX) along with a sharp jump in pressure.  That’s a satisfying conclusion to a day that started with sun (or fog, depending on where you were), and gradually clouded up.  Speaking of a pressure rise, a 6 millibar westerly gradient has suddenly developed through the Gorge…expect strong wind there in the next couple hours! 

Looking ahead, another system moves inland tomorrow afternoon, then another on Monday afternoon & evening.  Both of these will be juicy systems with plenty of mountain snow.

Things get far more interesting the 2nd half of next week.  Both the GFS and ECMWF are in general agreement on a pattern similar to what you see in the graphic above.  Very chilly air sweeping south out of Alaska, over the Pacific, and right in over us.  This is a good setup for heavy Cascade snow and snow to quite low elevations.  Since this is still 6-8 days away, details are lacking and change with each model and model run.

For example, the 12z ECMWF has thicknesses down to around 522dm from Thursday morning onward, cold enough with onshore flow to bring sticking snow down to at least 1,000′.  Then it shows cold easterly flow and a low pressure system approaching from the southwest on Sunday; possibly a setup for a brief snow or ice event, especially in the Gorge.  The 12z/18z  GFS was similar with snow in the hills Thursday and beyond.  It also showed some sort of clash between cold easterly flow and Pacific moisture around a week from Monday…only 10 days away!  Lots of fun to speculate, but for now the only thing I’m confident about is the snow levels down to at least 1,500′ late next week.  We’ll see how the rest pans out.   I guess I can also confidently say I’m done with my outdoor chores for the season.  I’ve built the shell of a greenhouse (for the next La Nina spring?) and just have to put in the windows when I get a break in the weather…maybe in February?

Stay warm and dry this weekend!

Chief Meteorologist Mark Nelsen

207 Responses to Cold Front Signals Big Weather Change

  1. W7ENK says:

    Dark threatening clouds all around, and it’s POURING!!!!!!!!!!

    Hang on, I didn’t get enough exclamation points behind that, it’s not emphasized enough…

    POURING!!!!!!!!!!!! ❗ ❗ ❗


  2. Jory (Sandy) says:

    Well, this day pretty much ended up being a washout. The NWS said 40% chance for rain. Try 100%. It rained pretty much the entire day here. Very heavy cloud cover.

  3. gidrons says:

    Not sure if this link will work, looks like the EMCF has white stuff for PDX around hour 132.

  4. 18z shows more moisture for Friday and Saturday…

  5. PaulB/Eugene says:

    Looks like snow stays confined to mountains, higher foothills through Friday….snow level bottoms out at 1500′ in Oregon it looks to me…the only chance for snow in Willamette Valley would be Sat night if the following low, instead of dropping toward northern California (as models suggest) heads for Central/Southern OR, with moisture overrunning a cool/cold airmass….looks like Bellingham may get a bit of Fraser outflow, but moisture may be limited.
    All in all, I would call this a decent cool, wet period for this time of the year and a good start to higher elevation snowpack. Not seeing arctic air here in the next two weeks. Beyond this weekend looks like we will be living in the PACIFIC Northwest instead of the Pacific Northwest….with lots of moisture, onshore flow, with snow levels fluctuating up and down…may be good enough to get Meadows/Timberline open within 7-14 days…even if ski areas open conditions up there may not be all that pleasant.

    Does not look like a Norman Rockwell white Thanksgiving for much of the country…..major East coaster weather bloggers had been anticipating a cold second half of November but they have backed away from that and seem to be resigned to waiting until December for any sustained cold weather there…looks like SE ridge a problem for then…no that we have much to brag about here in terms of cold weather here..either…have to head to AK/northern BC, YT to see subzero cold…it will stay there for now.

    Gut feeling once again…true arctic cold in Pac NW…if it is going to happen….will have to wait until at least mid Dec/early Jan……until then the more likely interesting weather scenario could be some sort of flooding pattern/windstorm or both…but that would take some influx of tropical moisture/energy from west Pacific to combine with cold air flowing S from AK into G of AK trough.

    • Good analysis Paul! Agree pretty much 100%.

      Earlier in the month I was thinking the resorts may be open by Thanksgiving, but I have a feeling now it might be close. There could be a great dump of snow up there Wednesday PM/Thursday, but then it dries out quite a bit before a warmer storm comes in early next week.

    • W7ENK says:

      Yes, excellent post Paul, thank you!

      I also agree with you 100%, though stating so might get me accused of either being arrogant, a nay-sayer, or just plain ignored for the rest of the winter, but nonetheless, I agree!

    • Jclack says:

      Thanks for taking the time to share your thoughts.. blog is very quiet for whatever reason..

    • NR says:

      Great analysis Paul.
      Looking long term I don’t see much chance of arctic cold until at December.

    • chris s says:

      I would have to agree with most of that assesment as well. I would think the only thing holding ski areas from opening by the end of this weekend would be personnel and operational things, and not from lack of snow. All the ski resorts should have a minimum base to ski on by Sunday I would think, except for ski bowl. Just my 2 cents anyway. 🙂

    • W7ENK says:

      I have a close friend who’s on ski patrol at Timberline and SkiBowl. I just spoke to him last night, he says they’re all geared up and rearin’ to go! Just waiting for the snow to start piling up…

  6. Wendy-Silver Lake says:

    We are under a very heavy shower at the moment and I kid you not, it’s chunky. Crazy weather. Just switched over to hail now.

    • Wendy-Silver Lake says:

      Guess it wasn’t hail, the gutters were overflowing and making a ton of noise. It’s all stopped now. I honestly didn’t think we were getting anything until the end of the week, but I guess maybe heavier showers are bringing it down a bit.

  7. At least here in Sandy, sure looks like a soaker today. I suspect some orographic lifting is occurring. We’ve had everything from drizzle, to several gully washers. But no dry time at all, in the last 12 hours at least.

    Time to head over to Clackamas Mall, so I can get some exercise, going around in circles. 🙂

  8. gidrons says:

    12z GFS a little colder than 6z. The spaghetti chart fairly consistent through hour 138, where a few models show a low just offshore. It could get interesting.

    Here is my first try at tinyurl:

  9. SnowedIn - North Plains says:

    Haven’t checked in the last few days, how’s snow looking for lowlands currently accoring to GFS/Euro?

    • SnowedIn - North Plains says:


    • Ryan (Walnut Grove) says:

      Haven’t checked the 12Z but the 06Z keeps snow levels at 1000′ or higher.

      Might be a chance heavier showers could drag snow levels down or give us rain/snow mix something Saturday-Monday.

  10. The 12z takes the second low on Saturday further west and has it a little bit stronger.

  11. pappoose in scappoose says:

    I think AccuWeather one-upped you with this pic, Mark:

  12. Austin (Cornelius) says:

    accuweather has Monday night next week at 36 degrees with winds gusting to 50…….(MODIFYING NAME)…………windy frost. that’s its name now.

  13. pappoose in scappoose says:

    I really like Winter weather issues:

    National Weather Service Portland or
    251 am PST Monday Nov 14 2011

    Long term…high confidence in well-below normal temperatures late
    in the week as medium range models show good agreement in a cold upper low settling over the Pacific northwest. The cold air aloft
    will result in plenty of showers through the weekend…with snow
    levels lowering to around 1000-1500 feet. 00z GFS/ECMWF/Canadian all develop some sort of low off the coast Friday night or Saturday… this will need to be watched closely the next few days as it could potentially cause some winter weather issues for The Lowlands if it materializes.Weagle

  14. bgb41 says:

    11/13/2011 Oregon (All) Temperature Summary

    High:59 at DW7774 Roseburg( 446 ft) & PROVOLT SEED ORC(1180 ft)
    Low: 51 at CW3485 Port Orfo(400 ft) & John Day River B(305 ft) & Rufus 2E(279 ft)

    High:26 at HOWARD Mt Howard(8150 ft)
    Low: 19 at Baker City Munic (3373 ft )

    Largest Diurnal Change: 27 degrees
    Baker City Munic (46/19 ) (3373 ft )

    Heaviest Rainfall:
    1.25″ at LOG CREEK(2800ft)

  15. Austin(Cornelius) says:

    Let’s see…snow at low elevations? Hmm…quite interesting. I guess this week will keep me in. If the cold front keeps it’s stability I will name it Jack…as in Jack frost. 😉

  16. Muxpux (Longview) says:

    A nice train has set up over Kelso/ Longview, for the better part of the day, though it’s not showing up on the KKLS obs. If this were snow we’d be the winners, much like last winter 🙂 but alas, just a soggy soggy day/weekend. 1.08″ for the weekend at KKLS, I’m sure some of the local wunderground stations have higher amounts

    • Emily Waldman says:

      I can testify to that! The culvert that runs water behind my house in the ravine is now a stream/creek level. That continues its journey to the Cowlitz.

  17. Triforce says:

    What happened to my question about Rob? I wasn’t attacking anybody. I was just curious to where he went and I wish to go with him. 🙂

  18. pappoose in scappoose says:

    Don’t try to fly to Asia…it will take forever. Hahaah!

    • Triforce says:

      I can see why no one posts on his blog because when I try to I just get sent to a white page with nothing on it. ????????

      I was going to ask if this was an east wind or a west wind event. Is that normal? I’ve never seen anyone mention it before on here.

    • pappoose in scappoose says:

      It is what it is. I think it’s explained quite well, Triforce.

    • Triforce says:

      So it’s not really an east or west wind event then?

  19. W7ENK says:

    Mark, I know you don’t like having the “GW” topic brought up on your blog since it is so politically charged, however I just discovered this extremely startling piece of evidence that I just HAD to share with everyone here…


  20. We had a nice road trip to the south coast this weekend. Ended up at Port Orford. Here’s the sunset view by the rocks at Bandon on Friday.

  21. pappoose in scappoose says:

    I really like it when the cold East winds, chase the incoming warm fronts!…and Boom!

  22. boringlarry says:

    people do forget
    remember winter pure joy
    sharing weather love

    • lurkyloo says:

      Larry, nice post. It’s nice to see some good vibes showing up.

      Way back in 1979 I had a best friend named Juli. Her dad Jesse sang a song that went, “Come on people now, smile on your brother, everybody get together, try to love one another right now.” Times don’t change much do they?

      Come on people …!

    • pappoose in scappoose says:

      I’m in.

    • boringlarry says:

      Her dad was Jesse Colin Young????????…too much!!!!!

    • lurkyloo says:

      That’s a given Pappoose! You always bring a nice mellow vibe to this blog. (Wow, my parents taught me well in the hippyness didn’t they?)

    • lurkyloo says:

      I know! How weird is it to know a celebrity but not know he is one because he’s only your friend’s Dad? He was just Juli’s dad to me. So odd. But his song does send a message for the ages I think.

    • lurkyloo says:

      except they never taught me to spell hippie. Ha! I feel like such a hippie poser now. see? we CAN have fun on this blog without fun weather!

    • pappoose in scappoose says:

      Thanks lurkyloo. I always try to keep the glass half full.

    • Yup, those were some nice tunes..I have an ” old” friend who lives on the island of Hawaii who occasionally plays music with Jesse Colin Young. Not to mention playing golf with him regularly. Such a small world!

  23. W7ENK says:

    It just started raining again in Milwaukie.

    I hope everyone had a nice weekend? Mine certainly was busy, and exciting! 🙂

  24. NR says:

    I’m seeing definite warming in every recent run of the GFS. The arctic boundary never gets close to the Canadian border and by the time the showers have cleared, the jet has turned to the west and a storm is on our doorstep. PDX AFD mentions this at the end.

    • Josh (Gresham) says:

      You obviously didn’t see 18z.. And yeah it shows a storm after the res change, after hour 180 the GFS is so unreliable..

    • bgb41 says:

      18Z is slightly warmer. NR is right.

    • Benjamin (West Salem) says:

      I noticed this slight warming trend on the GFS; however, for what it’s worth, the 12zECMWF showed colder temps and a possibility for some wintery precip down lower. just my take on the models… 🙂

  25. bgb41 says:

    Promoting would be a direct link. Just trying to help people understand why thing are the way they are.

  26. carverray says:

    “There are 2 large wx groups and my group gets hundreds of posts a day from a pool of101 members.” What’s your definition of promoting?

%d bloggers like this: