Colder Weather Next Week: Snow Update

9:30pm Wednesday…

Will it snow in Portland this coming Monday or Tuesday?  Sure, maybe in the air, but it’ll be far tougher to get more than a dusting down to the valley floor.  My thinking hasn’t changed much the past two days because models have been doing a very good job with the evolution of the weather pattern over the next week.  The end result is a cold upper-level trough descending on the Western USA

markjet_warm_coldseparated

A strong cold front moves through the region the 1st half of Sunday.  Behind it, the snow level (the lowest level in the atmosphere in which snow sticks) drops to around 1,500′ the rest of the day Sunday.  So the Coast Range passes may see some snow come and go during the day, and of course the Hoodland corridor from Brightwood to Rhododendron should see some snow too.  Models haven’t been showing temperatures cold enough for sticking snow lower than that Sunday, so I’m quite confident with this first part of the forecast.  We’ll see showers off/on Sunday with a few flake possibly mixed in at times here in the lowest elevations.  Temperatures hover in the low-mid 40s.

It gets more interesting Sunday night and Monday as cooler air continues pouring in.  By Monday morning, any decent showers should be able to drop a dusting down to around 1,000.  I’m pretty confident that if you live above 1,000′ you could wake up to at least a light coating of snow.  Here in the city it’s more likely we’ll just have scattered showers milling about Monday morning with any of them containing snow too.  Temps remain ABOVE freezing through the day Monday below 1,500′.  The ECMWF and the GEM both show onshore low-level flow and a mixing southerly wind continuing through Monday AM.  That generally kills the lowest elevation snow chances pretty well.  But not always, see the next sentence.

The one item I’m watching closely is the possibility of a more organized band of showers and/or surface low pressure center passing by Monday morning/midday.  THAT is the one thing that can drag the snow level lower in this pattern, and has in the past.  The GFS depiction of snowfall pretty much agrees with my general this assessment, showing any real snow staying out of the lowest elevations:

gfs_accumsnowtuesam

Just so we’re all on the same page.  This setup with cold showers streaming onshore Sunday night through Monday is not our “big snow/ice storm” pattern.  The big snowstorm almost always happens when cold & dry air is in place (usually via cold easterly wind out of the Gorge) and THEN moisture returns overhead.

Speaking of that, it appears we go pretty much dry Tuesday and at least part of Wednesday as drier and colder Canadian air fills in from the north.  We should finally have a widespread frost and some chilly daytime highs only around 40 degrees both days.

Models are then in relatively good agreement that a strong system pushes inland later Wednesday and Wednesday night to end our little mini “cold spell”.  The ECMWF (and to a lesser extent the GFS) imply this could start as snow even in parts of the valley, and for sure in the Columbia River Gorge.  I’m feeling somewhat confident that some sort of snow/ice “event” is on the way for the Gorge later Wednesday through Thursday.  I’ll be watching this closely as well because, as mentioned above, this kind of setup (with the cold air in place) can cause quite a bit more havoc with transportation through the Gorge and possibly in the metro area.   I noticed 28 of the 51 the ECMWF ensemble members show 2″ or more snow in Portland by next Thursday, lending a bit of confidence.

By the way, don’t forget one of my favorite websites…almost always right on!  http://isitsnowinginpdx.com/

Just for the Christmas season, the blog snowflakes are turned on as well…enjoy.  The astute reader will notice the angle of the snowfall will change as you move the cursor…that’ll kill some work time for you.

Chief Meteorologist Mark Nelsen

 

81 Responses to Colder Weather Next Week: Snow Update

  1. High Desert Mat says:

    Cookies

  2. pappoose in scappoose says:

    NWS forecast for Thursday, can’t miss unless it’s sunny and 70!

    THURSDAY…RAIN…FREEZING RAIN OR SNOW LIKELY.

  3. JohnD says:

    “…devils in the details…” as the saying goes. Usually Portland snow is not definitively forecastable until it is close to our doorsteps! Of course our pal Mark is as close to cutting edge as we can hope for. We’ll see. Fun stuff ahead–to greater or lesser literal degree!

  4. Roland Derksen says:

    I’ll believe it when i see it!

  5. W7ENK says:

    Okay, so I’ve settled my thoughts on the upcoming pattern: Through this weekend and into early next week, use December 2-7, 1994 as analog. This includes all areas along the I-5 Corridor from Seattle to Salem.

    Fingers crossed…

    • Matt (Vancouver 98683 @150ft) says:

      Fingers crossed is right! Pray to your snow god and let’s see what happens! Cold air first, add moisture, and ?

      “So you’re telling me there’s a chance?!”

    • Also, I want to say December 2009 when everyone was dead set against snow and we got 2-3″ before it changed to rain in the evening.

  6. High Desert Mat says:

    I bet a lot more people would post in here more if every time someone made a post they didn’t have to sign in again. I for one donut on my phone mostly and it’s a pain in arse. Any way around this nonsense Mark? It’s been like this for a long time.

    • W7ENK says:

      See, I don’t have this issue… My phone, my personal laptop or on the rare occasion I comment from my work PC while at lunch, I don’t have to log in but maybe once a month.

      If you’re using some scanning/cleaning tool to maintain your computer, be sure to add the fox12weather.wordpress.com domain to your protected or approved list. If your scan is wiping out cookies for this site, that might explain why you keep having to log in all the time.

    • pappoose in scappoose says:

      Pretty sure most folks aren’t always signing in, but who knows.
      I don’t have to on the desktop or laptop. Been months since I have.

    • If you toss your cookies on browser exit you will have to re-authenticate each visit to post.

    • High Desert Mat says:

      I get that Erik. But where do I do that on an iPhone so that I don’t have to keep up doing this?

    • Jason Hougak says:

  7. marinersfan85 says:

    WRF gfs shows a widspread 1-4″ Monday morning.

  8. GTS1K' says:

    The waiting is killing me…

    …T-Minus ~60 hours.

  9. SUNFAN says:

    Not looking to snowy know is it!!!! Maybe next time WKRP

    • SUNFAN says:

      now lol, my trolling has caused a misspelling.

    • MasterNate says:

      Actually spelled “now”

      Just FYI

    • JJ78259 says:

      I guarantee there will be enough snow in San Antonio for Sledding on December 10th. A local Catholic Church is renting 4 snow machines for a winter carnival celebration. See you there! Not quite sure how they do it but they did it last year!

  10. alohabb says:

    Looks as if other stations have backed off the idea of snow and are going with mid 40’s and rain. And my ever so reliable phone is saying the same thing. Models must have flopped.

  11. Windsday says:

    What will it do to plants/vegetation to have snow WITHOUT a killing frost before hand?

    Usually when we have snow we have had 1 or 2 hard freezes to ensure plant foliage is in nappy mode for the winter but this year other then maybe a light frost we haven’t had any cold temps.

    We still have some plants that are NOW just starting to wither.

    • Tyler Mode in Battle Ground says:

      Actually snow is a great insulator. Snow usually doesn’t get as cold as the ambient temperature.

  12. WRF-GFS now says 3-4″ for me on Wednesday. We shall see. I expect a fair amount of flipping and flopping as to the exact amount before the event happens, but at this stage it really does look like I will get at least some snow.

  13. Jason Hougak says:

  14. Jason Hougak says:

    Anybody checked the national weather map. Hawaiian Islands have flash flood watch on every island and the Big Island has winter storm warnings for the volcanoes for 6-12″ of snow. Winter kicking in full swing!

    For us bloggers I was wondering how much each of us enjoy snow. It’s my favorite weather which I’d give a 10. Hot 100 degree weather would be a 1 as I’m not a heat person. What weather is your favorite type and least.

    In anticipation of the snow I brought my dad’s four wheeler home to have some fun with the kiddos. Had so much fun as kids being towed in an inner tube through our field. So many snow memories and more to come!!!

    • Anonymous says:

      Big Island has a winter storm warning? Maybe up Saddle Road near Keck Observatory? I lived near there for almost a year. There was one big storm that knocked out roads and caused some flooding in the winter of 00-01. That one was fast and freakish … hope it’s not a repeat.

      I LOVE a snowstorm as long as I have firewood. I’m a damn fool for a fire on a cold day.

      I cannot stand hot weather unless I’m sitting next to water that I can jump into. Anything over 85 can pretty much KMA.

    • Joshua Downtown PDX says:

      I’m with you, Jason. Snow is my favorite. Next favorite for me is dark, gloomy, and wet. Moss and mushroom heaven. Hot and sunny is my least favorite.

    • Diana F. says:

      I’m exactly the same as Joshua! MAD for Snow. Ice is very fun, because everyone needs to stay home–it’s dangerous. Stormy, wet and windy would be next. Or dry windy. Foggy is good too of course. Hot and Sunny are you kidding me? I prefer Central California Coast 70s if Sun is a Must.

      Though cruises to islands are fun, I could live without it. Turbulent weather is something I cannot live without, and that started the first day I moved to the NW in the 70s, from California. Discovering 4 distinct seasons was life changing!

      Aren’t you glad you asked?

      And wow, are we in Storm Heaven right now….because living here, you need to get excited just with the possibility of snow…because it doesn’t usually happen, so ya gotta at least enjoy anticipation—-and we do!

    • “Big Island has a winter storm warning? Maybe up Saddle Road near Keck Observatory?”

      When Jason said the “the volcanoes” he meant Mauna Loa and Mauna Kea, both top out at over 13,000 feet. It’s not unusual at all for them to get snow. There’s even a few snow plows on the Big Island to open the roads to the summits after snowstorms.

    • runrain says:

      Thunderstorms, hands down, are my favorite.

    • Jason Hougak says:

      Thunder snow would be my favorite if it happened here.

    • Dave in South Salem (500') says:

      rubusleucodermis where do you think the Keck observatory is?

  15. Mike Hinnant says:

    ok…explain this weather peeps. I drove by the Les Schwab in Wilsonville today and the cherry blossom trees are blooming. what is that supposed to mean?

    • pappoose in scappoose says:

      Ya, I need to cut my grass again.

    • Boydo3 N. Albany says:

      There is a strain of plum that blossoms in the winter. Not a cherry. But usually don’t see it till Jan or Feb.

    • Tyler Mode in Battle Ground says:

      Since we haven’t had a widespread frost, plants send out buds. This next week should nip them a little bit, but others are correct, there are certain plums and bulbs that are already poking up. Usually not till January.

  16. washougal1100ft says:

    looking like middle of next week might be interesting? Lets hope models continue this trend.

  17. steve says:

    Mark

    Weather Channel has 4-6 in of snow predicted for next Wednesday. Lets say you.

  18. marinersfan85 says:

    GFS Euro NAM all looking good.

  19. Max in Fairview says:

    Well the latest EURO run makes things really interesting. I’m sure Mark will have plenty to comment about.

  20. Diana F. says:

    It beginning to sound a lot like Christmas! Snnnnooooowday!!!

  21. umpire says:

    Let’s see – driving to Boise on Thursday. Maybe I’ll leave on Wednesday afternoon instead! That’s what I get for entering 12/7 on the snowflake contest.

  22. Garron 1/3 of a mile from Hillsboro Airport says:

    wunderground.com tries to make it interesting Wed. If you click on Wed. for the PDX area, they indicate snow/snow showers for the majority of the morning hours with a 1 to 3″ snow fall potential. We’ll see….

    • About the same story up this way. It’s far enough out, and marginal enough for snow at the lowest elevations, that I don’t consider it worth a great deal of excitement yet. Still, it’s a far better outlook than a never-ending Death Ridge.

  23. W7ENK says:

    What really kills the time at work is trying to click one of those little buggers. They turn blue if you catch one!

    • pappoose in scappoose says:

      Surefire way to kill time.
      Love it!

    • Longview 400 ft says:

      Pappoose, where have you been? Missed your presence on the blog here. Happy Holidays.

    • Jason Hougak says:

      Pappoose… you in 😆

    • SUNFAN says:

      Most likely the closest thing to real snowflakes anyone below 1000 feet will see all winter. BOOK IT!!!!!

    • @SUNFAN – More than likely at least some of us below 1000′ will see at least some snow (if only flakes in the air) in the next week. The models are basically in agreement about this — and have been so for several days now.

      As I’ve said before: wishcasting in reverse is still a form of wishcasting.

    • pappoose in scappoose says:

      Thanks guys.
      Don’t ever doubt, I’m relentlessly on watch!
      Happy Holidays to you and all the weather geeks out there!

      Sure looks like with all these upcoming close calls for cold/snow, we’ll score at some point. My bet is on a surprise low spinning up off the coast, and/or a snow/ice storm with the cold air blasting down the gorge meeting up with moisture coming in from warmer locales……wait…..that’s the only way we ever get the goods!

  24. Benjamin (West Salem) says:

    Thanks for the update!! I noticed that tonight’s EURO run has a much better chance for snow and a longer period of snow for not only PDX, but also the mid valley as well. Much will change before then, but nice to see.

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