Showery End To November; Dry December Start

9pm Sunday…

The long Thanksgiving weekend is coming to a close this evening. We’ve had some pretty good weather! A dry Thanksgiving Day, then lots of sunshine in the metro area Friday. A weak system gave us a drippy day Saturday, with about 0.10″ total in Portland, then bright sunshine again today. Of course it’s been a different story south of town. Two of those days the fog & low clouds just wouldn’t go away. In fact today the southern edge of the metro area could be seen sitting in fog/clouds from our Skyline camera

Next spring when I look back for a winter recap, it’s obvious November will go down as a boring month. Sure, we had a couple of windstorms at the coastline, but no gusts above 37 mph in Portland. Temperatures ran near normal across most of Oregon and Washington

Rainfall ends up near normal as well…

…although slightly below in Portland

What’s Ahead?

A weak system moves into the region tonight, bringing a quick shot of valley rain and mountain snow, you can see the dip in the upper-level flow over us tomorrow

By Wednesday a strong upper-level ridge will have developed overhead

And it sticks around through the end of the week. 8 days from now the ridge is still there, although weakening quite a bit

It looks most likely that we won’t see significant rain again until about the middle of NEXT week; 9-10 days away. So it’s clear December will start quite dry. Notice lots of ensemble members from this morning’s ECMWF model show rain around next Tuesday/Wednesday.

Models have been consistently advertising that change about 10 days out for several days now. Will the upper-level ridge back to the west and allow some cold air to come down from the north, or do we go back into some sort of wet westerly flow? Too soon to know, but I’ll be watching that closely

In the meantime, the strong ridging means a classic “gap wind” event is on the way for the Columbia River Gorge. High pressure pops up east of the Cascades behind tomorrow’s system. For the first time this season a cold surface high develops late Tuesday and into Wednesday over the Columbia Basin of Eastern WA/OR. The WRF-GFS has been showing about 10 millibars worth of pressure gradient through the Gorge by sunrise Wednesday. That’s the only one sea-level gap through the Cascades and all the wind is headed there.

At the same time, temperatures at 850mb overhead reach around +10 or so, that will be quite an inversion! It’s a classic setup for extra-strong east wind in the western end of the Gorge plus out into the east Portland/Vancouver metro area. Check out the thin layer of easterlies in the WRF sounding from Wednesday afternoon to Saturday.

When the east wind layer is “squished” relatively low to the ground by the strong inversion, two things happen:

1) We don’t get a widespread wind event like Labor Day, but most wind remains confined to central/east metro and the West Hills.

2) The wind is even stronger IN THOSE AREAS as opposed to when it’s widespread over the entire metro area. Same volume of air is forced into a smaller “channel” = stronger wind.

Expect wind gusts 35-50 mph east metro and 60-80 mph in the west end of the Gorge Wednesday-Friday. Yes, this setup should produce 100 mph gusts on the steps of Vista House. If not Wednesday, then Thursday or Friday. The wind sensor there is offline, but the new part should arrive this week, hopefully it’ll start working again.

TO SUMMARIZE

  • There’s no sign of a stormy weather pattern and/or lowland snow/ice in the next 10 days. That’s through December 9th
  • Other than light rain tonight and Monday morning, we should be mainly or all dry for the next week
  • Expect lots of sunshine most areas west of the Cascades Tuesday afternoon through the rest of the week
  • Prepare for a very strong “winter-strength” east wind episode for at least 4 days starting Tuesday afternoon in east metro and western Columbia River Gorge

That’s it for this evening, I’ll be back on TV at 10pm. Enjoy the rain later tonight and bright sunbreaks following the showers tomorrow afternoon.

79 Responses to Showery End To November; Dry December Start

  1. Mr T says:

    A week from today in 1941 will be the very last public weather forecast ever issued………….that is until 1943 when limited weather forecasts would be released showing the weather from the day before yesterday and only a general forecast limited to that region with precipitation rounded to prevent exact figures.

    The only reason the limited weather was released was due to a huge tornado outbreak one of the deadliest nobody was allowed to know about!

  2. Piggy (Ziggy’s Brother) says:

    Very windy today, that east wind certainly has a bite to it as well. It reminds you that winter is near. Has anyone seen any thoughts from our excellent gradient keeper Rob Grimes on this wind episode, and what may be coming over the next month. I see WV Ken chiming in occasionally, but he is more of a “poor mans” Rob Grimes. I think we have some big changes that will be happening right around New Years.

  3. Roland Derksen says:

    A sunny day in December is a blessing- in my estimation, it’s never boring! We’ll see plenty of rain this winter- maybe some snow, but I appreciate the sunshine.

  4. Ken in Wood Village says:

    Looking at the latest model runs, it’s looking like starting next week we will start getting into a little active weather. Not the greatest stormy weather but it’s something better than just having sun all the time…lol. It also looks like we will be cooling off a lot compared to being in the 50’s so if you like this nice warm weather, soak it up because we will start seeing highs in the low to mid 40’s which means we could be in the 30’s until late morning.

    I know this is still a long ways off so things could change between now and next week but I’ve been seeing a trend so I think it’s a good possibility this will happen.

  5. Andy says:

    We just had a 3.4 earthquake NW of Salem in the coast rang.

  6. JERAT416 says:

    I had a random dream about the weather last night. The forecast was calling for at least a foot of snow for the ENTIRE state, except the Portland metro area, where we were supposed to get less than an inch. So I guess the dome expanded a bit in my dream hahaha

    • Piggy (Ziggy’s brother) says:

      That would be pretty special. I wonder what Rob Grimes would have to say about it?

  7. tim says:

    The NWS just issued a boring weather warning for the next two weeks at lest, so stock up immediately.

  8. Ziggy says:

    Looking long range you back home are screwed for winter action. Over here we should start having snow/ice in around 15 more sleeps!!!

    Enjoy and I will update as the winter gets over here👍👍

  9. Larry says:

    Guys, it’s that time of year again…imaginary snow! Although I don’t see any imaginary snow on the models. Maybe that’s a good thing.

  10. Joshua Lake Oswego says:

    The weather outlook for this time of year could not be more boring. There is nothing exciting even hinted at in the next couple of weeks. The theme is high and dry.

  11. Ziggy says:

    Does Rob Grimes ever comment in here? I sure would like to get his vast knowledge on east wind events for the next time. He is super smart!!

    • Jake in Gresham says:

      I saw him briefly post in October or so but he hasn’t since. He lurks, I’m sure he’ll chime in if we get any kind of chance come over the horizon.

    • Piggy (Ziggy’s brother) says:

      Rob Grimes is really a master forecaster. His FaceBook group is top notch, and even without professional training, Rob is a subject matter expert when it comes to our weather here in the northwest. I hope to see him post here more often.

      Looks like pretty normal/boring weather overall the next couple weeks. I’m thinking anything cooler and more winter like will wait until early 2021.

  12. Mountain Man says:

    It still is a weird thing when downslope wind slowly becomes a gap wind event, when just supposed to be a gap wind event. I lived in the gorge for 12 years at 1200 ft 6 miles eastnortheast of Cape horn in the edge no-man’s land, the edge or civilization it seemed, before I moved into the foothills southwest of Mt Rainier two years ago. This would happen there, when the wind would get shallower but stronger until it was lower than me. Last night I recorded a peak gust of 96 mph at 12:52 am on my Davis home weather station, was so loud, everything crashing everywhere,,, then, nearly calm now. I’ve been chainsawing all day and still not done clearing the roads/driveway on my land. At least 25+ trees down. I had no idea it was going to be this bad here. No power all night last night, but was pretty fun to listen to, not quite as fun cleaning up. The awesome power of a downslope wind!

  13. Tanis Leach says:

    Update to my winter weather forecast and a new historically significant trend I found:
    December needs 5.3″ to hit 12″ of rain thus far in the water year (2″ below average). At this time, it does not appear that we’ll hit 5.3″ this December. Taking all the years that were below that amount, only 1 year turned out to be above 40″, but that year had the wettest August on record, so it is excluded. There were 3 years around 39″, but the rest were below normal (36″). 3 years had a la nina occur as well: 1988-89, 1999-00, 2011-12. Conversely, the moderate to strong la nina minimum is around 30″, but those la ninas (2017-18 and 1984-85) did not make it into this analysis, as they did not have similar atmospheric and oceanic conditions.

    Therefore, I can say my precipitation forecast will decrease. How much is still in question, and how the other 5 factors are affected is still unknown.

    For a starting point, my October forecast for the water year precipitation was: 37-47″ Best Estimate 43″.

  14. Ken in Wood Village says:

    The 00Z GFS just became a little more interesting in the long range forecast. I’m not saying it will happen but we should start watching the extended forecast around the 9th and beyond because it looks to start getting a lot colder!! 🙂

    • Evan -- Cedar Mill says:

      You never know…

    • Ziggy says:

      Looks like 38 and rain, same as I will have here in Sofia. Nothing worse than cold rain. Maybe you get some cold air from Russia if the ridge helps out.

      Enjoy, we feed chickens today with my babushca!!!!!

  15. BenningtonCouv says:

    Will the strongest wind at crown point be tonight?

    • Ken in Wood Village says:

      It will be tonight into tomorrow morning then it will die off later in the afternoon.

  16. Roland Derksen says:

    Love the sunny skies today- and the days ahead. I needed this- my stats for November show an average amount of precipitation (8.81 inches) and mean temperature, but we had a lot of clouds to keep things dark and wet. I will enjoy the change.

  17. Tanis Leach says:

    November Stats for those that care for PDX:

    Temperature departure: -.2 (near average)
    Precipitation: 5.28″ (near average)
    Highest gust: 37 mph

    First 5″ November since: 2017

    I’d also like to note that there is minimal correlation to the return period of cold air. While its true the odds decrease if there is a cold snap or arctic blast, the full story is different. Examples: December 2013 had a major arctic blast and snowstorm (S Valley), but there was another one during February 2014. January and February 1950 had multiple back to back (I believe 3). The one closest to this year would be October 2003, which followed with a arctic blast in January 2004. It should be noted that 2020 had colder late October temperatures than October 2003. Conclusion: It’s not always about what the pre-winter temperatures are, but the atmospheric conditions at any given time.

  18. Ziggy says:

    Right now in Sofia it is a chilly 30 degrees at 730pm, looks like we are going to be in the mid 40’s by weekend.

    I hope I didn’t bring the boring back to my family. I think once I get to farm in Vratsa things get exciting, fingers crossed. Don’t worry I keep you all updated after long donkey ride 😂

    • Mr T says:

      Does anything ever shut down for snow over there or are they used to it like how SLC never shuts down?

  19. Andrew says:

    I’m not seeing anything in models to suggest a good shot at lowland snow. In fact, we look to stay pretty dry through first half of month. One sign of encouragement however is a build up of much colder air to our north. Nothing out of ordinary there for this time of year but so far haven’t seen the cold. Inland BC has looked unusually “mild” over past couple weeks. Things look much more normal by the middle of the month. Barring any radical model movements, i hope the quiet first half of December will portend a more exciting second half.

  20. Ziggy says:

    Historical dry and boring winter is on tap for the PNW, I’m getting on the plane for home in a few. I will update everyone with my snow pictures from Bulgaria soon my friends!!

  21. Weatherdan says:

    The Winter will come. The snow will fall. Stay safe my friends, and Merry Christmas to all. Peace.

  22. Jake in Gresham says:

    I’m very excited for this Winter, a lot of my siblings went sledding up at Mt. Hood and didn’t have to go far to find the snowpack. There is plenty to keep the arctic air chilly. Russia had an impressive icestorm (1in of zr in the Pacific coastal city of Vladivostok).

    Some good photos here:
    https://www.rt.com/russia/508205-climate-environment-citizens-poll/

  23. tim says:

    I forgot, record cold/snow for spokane

  24. tim says:

    Runrain, we did have a cold snap in october so that might have been our winter.

  25. Roland Derksen says:

    Great to see the sun this afternoon, though we had to go through a period of strong winds from the west to get it. So now that November is almost done, I’m ready for some sunny days in December!

  26. runrain says:

    In past years when we’ve gotten a snow event in November I can remember the sentiment being the winter was going to be great. Then, as winter progressed it would only be warmer or drier than normal. So I agree it’s to our advantage to be warm and/or dry early and see that turnaround to cold weather come along in late December or January.

  27. W7ENK says:

    “Rossby,” my finders apparently tripped over the keyboard and I didn’t catch it until now. My bad.

    It’s the typical (usually pentagonal) long wave sequence of troughs & ridges rounding the globe in either hemisphere.

    It appears as the result of perturbations of the Polar Vortex, which (obviously) becomes more active in the Winter months, and thus becomes a primary driver in Wintertime weather patterns. It’s the reason why when a deep cold trough punches down through the Midwest and East Coast, we typically get warm, dry ridging. It’s also why the inverse is typically true, when we get a nice cold blast coming down the West Coast, the Eastern 2/3 of the US is generally warm and sunny. The East coast is (roughly) offset by 1/2 Rossby Wave from the West Coast, or in other words, we’re ~120° out of phase from the central Midwest and ~180° out of phase from the East.

    Follow that sequence and you’ll see the pattern. For us to get the cold, you want to see a high pressure ridge push up out of the Gulf into the Midwest and East, as well as somewhere out around the International Dateline. To get a good, prolonged run of cold here, that’s where you want the pattern to lock, though that scenario seems exceedingly rare for some reason, and more favors locking somewhere in between. These waves also tend to unlock and shift about 6 times per year, on order of about every 8 to 9 weeks (or so), split between the hemispheres. In the past decade, the warm phase tends to lock over us dead center in the Winter months, however if that shift happens earlier or later than Median center of Winter, we can get the goods on either end. Ideally, we would want to see a shift into cold phase in mid December that locks in for that +/−8 week duration, right in the middle of prime-time. Several times in the last decade, however, that shift doesn’t happen until it’s too late in the season.

    ❄️ 2011 – late February
    ❄️ 2012 – late February
    ❄️ 2014 – early February (OK for a good blast of Winter, but didn’t lock)
    ❄️ 2015 – late February (was extremely bad)
    ❄️ 2016 – early March
    ❄️ 2017 – early/mid January (favorable for later Winter)
    ❄️ 2020 – mid March

    It’s definitely something to watch, as those changes either upstream and/or downstream could be easier to identify in the models, and why looking specifically at this area with blinders on to the rest can be difficult, if not aggravating for model riders. For a loose analogy: Don’t just look at the road 10 feet in front of your car when you’re travelling down the freeway, look at everything up ahead, and keep checking that rear view, too.

    • W7ENK says:

      That was in reply to Tanis, no idea why it popped out up here.

    • Ziggy says:

      So it’s a glorified wishcasting model!

      Neat🤡🤡

    • W7ENK says:

      To continue on this subject, another factor at play here that ties into this fairly closely is the recurrence of SSW (Sudden Stratospheric Warming) events. Major SSW events typically happen on order of about once every 2-3 years. No one really know what causes this, but in a Major SSW event, a slug stratospheric air in the polar regions (above 60N or below 60S) will suddenly (over the course of just a few days) rise in temperature by upwards of 120°F. This slug of “hot” air then rises upward to the 10mb levels, causing a complete reversal of the upper level wind direction around the Pole, thus a severe disruption of the Polar Vortex. This usually results in a mass ejection of cold polar air toward the equatorial latitudes. In the past, this has usually provided our best opportunities for Arctic blasts coming into our region.

      This would also be a major component to watch for, though the models won’t pick it up until during or just after it happens, and due to the unpredictability of such events, they don’t handle it well at all. Chaos theory in fluid dynamics.

    • Tanis Leach says:

      Thank you so much for this information, that defiantly helps.

  28. Jason Hougak says:

    Very windy and stormy up here in the Cascade Foothills this morning. Gusts are shaking the house and trees, I wouldn’t consider this a weak system.

    • W7ENK says:

      Strange! Winds have been light and variable all morning down here in the lowlands. Showers and sunbreaks here since sunrise, average wind speed 1, max gust so far 6, currently sitting at 0.

  29. ocpaul says:

    I don’t find the great snow pack in the Cascades, ‘boring’.

  30. donaleen Kohn says:

    I love boring.

    On Sun, Nov 29, 2020 at 9:30 PM FOX 12 Weather Blog wrote:

    > Mark Nelsen posted: ” 9pm Sunday… The long Thanksgiving weekend is > coming to a close this evening. We’ve had some pretty good weather! A dry > Thanksgiving Day, then lots of sunshine in the metro area Friday. A weak > system gave us a drippy day Saturday, with about 0.10″” >

  31. tim says:

    Artic air in december is unlikely here and most of canada/usa according to cfs model which has been very presistance lately,most likely a wetter wnw flow instead.

  32. W7ENK says:

    Let’s get this dry ridgey stuff out of the way early, wait just a tad bit longer to flip the switch. Wait until it actually matters and makes a difference. Flip too early, it flips back to bad during prime time, before flipping back to the goods when it’s too late for us. This is a good thing, so long as it doesn’t continue.

    We’re priming for a fantastic Winter.

    • Ken in Wood Village says:

      I’ve been looking at the extended forecast on multiple models. There could be a hint of colder air sometime in the middle of the month. I know, it’s a long ways out but I just wanted to point it out!!

      • W7ENK says:

        With the extreme cold punch currently ongoing in South-Central Russia, I wouldn’t be surprised to see a similar pattern here in 3-4 weeks. I’ve seen it many times before:

        ❄️ January/February 1996
        ❄️ December/January 2007
        ❄️ November/December 2008
        ❄️ December/January 2017

        Just a few examples of this pattern I’ve seen play out in the past. Rosbby Waves. They shift and lock in a specific progressional pattern. I believe our cold phase is coming, so keep an eye out for the Dec 20-27 timeframe.

        I’m ever hopeful…

        • Ziggy says:

          😂😂😂😂😂😂 ok Grimes

        • JohnD says:

          Agreed!

        • Ken in Wood Village says:

          Thank you for your detailed weather geekiness!! I was just looking at the 06Z GFS and at the end of the model run, it’s showing 850mb temps from -1C to -7C. The GFS has been showing a trend of cooler weather at the end of the run for a few runs. I know it’s way out there and probably won’t happen but it’s nice to see it.

          There is something else I thought of but I forgot, it happens when you get older!!!

        • Tanis Leach says:

          I’m noticing that too. We’ll see what happens when we get to that timeline but I’m hopeful. The Yukon would also be important (caused the Feb 89 arctic blast). Though I’ve not heard of Rosbby waves (petition to add to my ATS 310 (meteorology) curriculum?)

        • Ziggy says:

          Here we go again with Tanis😂

    • Ziggy says:

      Keep the faith 👍👌👍👌👍👌👍👌👍

    • JohnD says:

      I’m feeling it as well Erik!

  33. Ken in Wood Village says:

    Thank you for the update Mark. I think we will see dry weather for awhile but we probably see rain again later in the model runs. There is a little hint of it around the 12th on both models.

    Well see how things go. I just wish the weather station up at Crown Point was working. I like to see how strong the winds are going to be coming up this week. Maybe someone could tell someone it’s not working!!

    Have a good week 🙂

  34. Emmanuel says:

    Stick a fork in it this winter is over haha

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