About that Sunday snow…plus lunar eclipse tonight and drier weather ahead

2pm Monday

Yesterday was a strange weather day, nestled in a chilly & wet weekend. I have been sick since late Friday, so I was actually in bed much of Sunday. Nothing serious, and I’m on the rebound so I’ll be back at work this evening. But I want to recap the surprise snow to some lower elevation spots during the daytime Sunday. To get snow to the valley floor on November 6th? Everything has to be exactly right for that to happen.

You may recall we had the atmospheric river and initial cold front pass through Friday and Friday night, models just nailed that one with about 2″ rain in the center of the metro area and 8-10″ in the wettest parts of the Coast & Cascade ranges. Then we were in the scattered showers behind the front Saturday; an uneventful weather day.

A cold front was forecast to move onshore Sunday morning and this would be the leading edge of cooler air. Snow levels would come down to around 2,000′ at times Sunday (the forecast), and 5-10″ would fall in the Cascades. That DID happen. Models were also forecasting very heavy rain to fall south of the Portland area down into SW Oregon with yesterday’s system. Note the rainfall forecast with very heavy rain south of Salem and down to about Roseburg. This is from the WRF-GFS model. That DID happen

Then notice the snowfall forecast for 4am Sunday to 4am Monday…almost all of this was expected before sunset Sunday when precipitation changed to showers.

A closer view shows that there would likely be spots with snow below 2,000′. This forecast would imply anyone could see snowflakes mixed in and it could stick down to 1,000′ in the Cascade foothills around Silverton, Mill City, & Sweet Home. That DID happen.

So there were hints that snow could fall down to at least 1,000′ as the cold front slowly moved south. But it’s very tough to get snow down to the valley floor anytime, and really tough so early in the cold season.

What Happened?

This was another case of extremely heavy precipitation dragging the snow level all the way down to sea level (or the valley floor) under calm conditions. In 3 hours, Corvallis and Eugene both picked up about 3/4″ inch of rain, and Salem saw 1.13″! Portland’s rainfall was less intense, at .55″ in 3 hours ending at 10am, although temperature did drop to 40. The heavy precipitation caused the sticking snow level to drop 1,000′+ lower than it “should have been”. This happened during the April 11th snow event, and our first snow event back on December 18th last year when 0.5″ fell in Portland on a soaking wet Saturday night. Except models caught the change to snow ahead of time during those two events. This time they did not. Sometimes it’s called an “anafront” as well, when most precipitation occurs on the back side of a cold front. Looking back at maps, I don’t even see an obvious signature this could happen. The wind WAS forecast to go mainly calm in the valley. One other complication yesterday was that the Portland radar seemed to be having some issues which made diagnosing what was going on difficult. You can see the WRF-GFS did imply wind wind go calm at Corvallis (circled area around 10am-4pm lowest part of atmosphere). Then southerlies would resume during the night and lift the snow level again. That DID happen. Most of us warmed during the night at the lowest elevations

This isn’t a perfect map, but at least those that reported snow to the COCORAHS network. You can see the snow reports in the southern valley, mainly up against Coast and Cascade range foothills

To summarize…1-5 degrees can make all the difference under heavy precipitation, calm wind, and a relatively low snow level. Magical things can happen, but most times nowadays the highest resolution weather models will catch that “magic” ahead of time. This time they didn’t.

What’s Ahead?

Much drier weather is ahead! How quickly the mood has changed; 4 months of dry weather followed by 2 weeks of wet and I’m already excited by a dry spell. At home in the western Gorge I’ve picked up over 10″ of rain since the dry spell ended. Portland has seen 6″; things are soaked nicely…

The cold upper level trough overhead…

Will slide east of us and be replaced by an upper-level ridge and a sort of “split-flow” later in the week.

This means if any systems make it through the ridge, they will be weak with respect to rain/wind/snow. This is generally a very “boring” weather pattern for meteorologists, but good for regular folks that don’t want weather to mess up their life.

https://889c5c4a6f57e35c7fe84ff00b8b34d0.safeframe.googlesyndication.com/safeframe/1-0-39/html/container.html

A fun/neat chart below shows the dry spell the rest of this week (after this evening’s showers) and mainly dry for at least part of next week.

It’s 6 hourly precipitation for the next two weeks based on the 51-member ensemble ECMWF model. Each horizontal line is one model run (each 12 hours) and the latest is at the bottom. Taking a look at that bottom line, I’ve boxed in this work week and next (1 & 2). Little/no chance for rain the rest of this week, and just light amounts for next week. Remember these numbers are averages of many ensemble members, so if just 5 of 51 members show rain on a certain day, for example Monday of next week, it’ll just show light amounts. You can go back 3 days worth of model runs (boxed weeks up above) and see how the model has gradually dried out this week’s forecast as we get closer.

Temperatures will be a bit cooler at night as drier easterly flow develops this week. Not any sort of arctic chill, but long overdue frost for outlying areas. Mid-20s wouldn’t surprise me in the colder suburbs within the next week and finally some sub-freezing temps in the city either Wednesday or Thursday morning. East wind does not look especially strong for this week, just the usual areas near/in the western Gorge turn windy. But that’s normal…it’s November.

Total Lunar Eclipse Tonight

It’s nothing like a total SOLAR eclipse, but we get to experience another total lunar eclipse in the middle of the night. We typically get 1-2 a year. I’ll be asleep, but if you are awake, the moon will be fully eclipsed in earth’s shadow from around 2:15am to 3:45am Tuesday morning. It may be visible since clouds will be breaking up a bit during the night. Cloud cover forecast says all hope is not lost…partly cloudy across much of the region

Cloud cover forecast for 1am Tuesday
Cloud cover forecast for 1am Tuesday(KPTV)

I borrowed this graphic from a sister station. SUBTRACT TWO HOURS since this is showing central time.

Eclipse timeline for SWLA
Eclipse timeline for SWLA(NASA)

40 Responses to About that Sunday snow…plus lunar eclipse tonight and drier weather ahead

  1. tim says:

    Gfs is showing a return to a more typical late November pattern but nothing out of the ordinary of course after all it is the pnw aka boring, I can’t wait until spring sun and fun.

  2. WEATHERDAN says:

    30 with pea soup fog for this morning. Now hazy sunshine and 40. What a perfect Autumn day it is. Then again any day without an atmospheric river flooding my basement is a perfect day. Only around 5 weeks until the sunsets start getting later. Happy Thanksgiving to one and all. Peace.

    • tim says:

      I see your already thinking about spring and summer by mentioning the longer days soon, likewise this storm season will fly by.

  3. tim says:

    Cliff mass new podcast explains why the persistence ridgeing is caused by la Nina and we should expect it most of the winter, he said get used to it.

    • tim says:

      Apparently la Nina doesn’t always means cool and wet during the fall/winter months or at least wet, I thought it always did.

      • Tanis Leach says:

        The 2nd (or 3rd in this case) La Nina is almost always drier than the one that preceded it. Only 1 exception through all of ENSO years. 92-94% frequency (too late to do math). Last year was the median year, so you can take it over from there to figure out the odds of a drier than normal winter.

        • Opie says:

          The transition from El Niño or neutral to a La Niña has a cooling effect on the atmosphere. I’ve speculated that this would cause temperatures to drop below the dew point in many locations, increasing global precipitation totals (if such a thing could be measured).

          A second or third year La Niña often does not produce as much of a temperature drop, sometimes none at all, in which case I’d expect precipitation totals to decrease and return to about where they were before the first year La Niña.

          I’m not saying this explains what happens here in the PNW, but it’s something to ponder.

  4. lurkingsince’14 says:

    Nice little flurry just passed through Welches, feels like it could be a solid winter ❄️

  5. tim says:

    Cfs model is cold and snowy going into December but it’s unlikely.

  6. Roland Derksen says:

    Up til today (November 10th) the total amount of precipitation I have this year compared to last year is almost equal: Just 0.51 inches more. That will change dramatically in a few days, as on the 14th-15th we’ll be marking the 1st anniversary of that big AR that caused flooding in the Fraser Valley. This year, it couldn’t be more different, as we’re expecting sunny skies

  7. tim says:

    November is looking dryer then normal and cooler than normal as of right now this will be a short storm season come march sun and warmth thànk Goodness.

    • Roland Derksen says:

      Don’t look ahead so far. Things can change and we’ve got a lot of weeks to go to get to March.

  8. Mountain Man says:

    The unusual, I wasn’t a snow winner this time. Could only get a half inch of slush Sunday night and a little flurries event Monday evening with the slightest dusting. Last night though, my very first frost this year and it went all the way down to 23 and stayed frosted in the shade all day. Well, I’m watching the models and a lot of scrambled ensombles after 6-7 days, but many, about 50% look quite interesting 8-10 days out so we’ll see, maybe some fun just before Thanksgiving which isn’t as unusual as early November snow possibility.

  9. WEATHERDAN says:

    GFS 16 day meteogram has a major snowstorm of maybe 9 inches hitting Portland on November 18th. Followed by days of fake cold but dry. Within the ten day time frame. Interesting to see if it pans out. Matt Zafino was alluding to something cold happening around the 18th a couple of days ago. Mayhaps there is something to all of this. Salem had i’s first frost of the season this morning at 29. Welcome to Winter. Peace.

    • Joshua Lake Oswego says:

      That BC slider is long gone already. Looks extraordinarily dry the next couple of weeks.

  10. Jake says:

    The 12z Euro is saying NE gets a snowy Thanksgiving not really seeing it here. Seeing rotation of the polar vortex super clear in that region for next week.

    If I saw any building up against the Rockies on the 850mb I’d be excited but it’s the Great Lakes turn.

    Anyone find it odd that the GFS has been leading as of last year or so on major events? Did it get updated?

  11. Evan -- Cedar Mill says:

    00z GFS operational has potential…

  12. tim says:

    November 8th and no freeze proves our warming climate get used to it, before we know it it will be Florida in the pnw.

    • Anonymous says:

      Your comment at 2:28 and this comment are extremely contradicting to eachother

    • X says:

      I’m not surprised for reasons that would get banned on here going against the narrative.

      Don’t you just LOVE Orwell?

      • Gene says:

        You don’t get banned for going against the “narrative” — that’s a really stupid thing to say. What narrative are you talking about? The fact that the weather is interesting and people have different opinions? The reality is, you get banned here if you break the rules, plain and simple — nothing more complicated than that.

  13. tim says:

    Winter in early November strange but at least there’s two sides of a coin this can’t last forever.

    • X says:

      We are essentially 1,000AD now in terms of climate/jet stream pattern so whatever happened back then is a cursor to our future the peak will be 100 years from now. 🙂 Can’t say anymore or I will get the 1984 digital police on me.

  14. Jake says:

    Micheal’s weather outlook included some pretty nice snowy photos of Vancouver, BC for those interested:

    • Roland Derksen says:

      Yes- it was very pretty here this morning, with the sun shining on the mountains north of the city, and the thin snow cover.

  15. Roland Derksen says:

    Half an inch of snow here late last night- I was expecting something, so I’m happy I was right. However, next few days are dry and mostly sunny. Anytime we get sunshine here in November, it’s welcome.

  16. ViRGE says:

    “One other complication yesterday was that the Portland radar seemed to be having some issues which made diagnosing what was going on difficult”

    For anyone in the know, what is going on with KRTX? I noticed it was offline for part of this morning. And looking now it hasn’t turned in fresh data in almost an hour.

    The NWS has not posted any messages about the matter that I’ve seen (nothing on the NOAA status pages), so I’m wondering what is up with our local radar.

  17. WEATHERDAN says:

    I see that Matt Zafino was mentioning a possible mid month backdoor cold blast. Fine with me. The water in my basement is not. We are now close to 4.50 inches of rain since Friday afternoon. However the moon is now out. Thank heavens for sump pumps. Peace.

    • Andrew says:

      Seems a bit strange to me that Zaffino, whom i’ve always viewed as fairly conservative and short-term focused, would mention a scenario that really isn’t supported in current models. I’m certainly not disputing the validity of the statement that he mentioned it but it makes me wonder what specifically he is looking at. No hint of a arctic air event (back door or otherwise) in any of the major ensembles last i checked.

  18. Evan -- Cedar Mill says:

    Potential for death ridge to set up shop… unless it moves west.

    • Doinko - Bethany says:

      12z Euro was hinting at that, ridge backs up and then a big backdoor arctic blast. The 12z GEM also shows something similar.

      • Evan -- Cedar Mill says:

        Hopefully that materializes because otherwise the plains and Midwest will get the cold. That is usually what happens, especially with the Rockies as a topographical obstacle.

      • Andrew says:

        It wouldn’t be winter without a couple death ridges. I just hope we don’t have one for six straight weeks during prime cold season. Basically half of last winter was dominated by ridge.

    • ViRGE says:

      Please no more death ridges. I don’t need two weeks straight of rain or two weeks straight of sun. Sun one day, showers the next, going back to party cloudy; that would be far more pleasant.

    • MasterNate says:

      The Death Ridge always cometh. Better to have it now than in December or January.

  19. WEATHERDAN says:

    Since Friday Salem has had 4.28 inches of rain and a little snow. This is more than we received between June through October. Now we enter into two weeks of cool but mainly dry. Much better in my opinion. Peace.

  20. WEATHERDAN says:

    First. Peace

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