Snow, Freezing Rain, and Long Range Outlook

9:30pm Friday…

We have one more round of freezing rain and snow in the Columbia River Gorge this weekend before a dramatic warmup (even IN the Gorge) early next week.

Here are the highlights:

  • Dry tonight, not much happening except east wind continues to increase in the Western Gorge.  Gusts 60+ mph are likely through midday Saturday.
  • Light rain showers arrive in the metro area midday tomorrow and continue through Saturday night.  It might even turn to steady rain since this next system is a bit wetter than yesterday’s.
  • It’ll be at or below 32 degrees during that time from Corbett eastward into the Gorge.
  • Freezing rain (glaze ice) again from that area out to around Bonneville.
  • 1-3″ snow is likely Saturday afternoon through late night from Cascade Locks to The Dalles. 
  • I-84 might be okay during the daylight hours then freeze up around sunset since the air mass will be slightly warmer this time (by all of 1-3 degrees).
  • The Gorge should be clear (temps 35-40) by midday Sunday.  Then a west wind Monday means a jump to around 45-50 degrees!
  • Monday & Tuesday will be very mild with high temps into the 50s

Last night’s system knocked down the cold air a bit that’s stuck in the Columbia Basin, but not much.  The cold pool is still about 3,000′ thick or so stacked up against the east side of the Cascades.   The pressure gradient from Troutdale to The Dalles dropped as low as 4 millibars this morning, but has increased dramatically the past 6 hours to over 8 millibars again!  This is maintaining a cold flow of air from east of the Cascades westward into the Portland metro area.  Notice PDX made it to 42 today, but Eugene was a “subtropical” 53!

The approaching splitting system sure doesn’t look impressive, but it is a little wetter than yesterday’s system.   Forecast soundings definitely say snow from the central Gorge eastward to The Dalles.  The cold pool is 3,000′ thick and the actual snow level is around 3,000′, so that means flakes survive all the way down. 

MarkSnow_Gorge_ColdAirTrapped

West of Bonneville the cold air thins dramatically, only around 1,500′ thick by the time it passes over Crown Point.  So just freezing rain (again) in those areas from tomorrow afternoon through early Sunday morning.

MarkSnow_Gorge_ColdAirTrapped2

Let’s look farther ahead…

All models in general agreement with a mild and wet system over us Monday and Tuesday, then a sharp cold front for Wednesday morning at the latest.

Behind that cold front, we get into the classic “cold showers, how low does the sticking snow go” pattern.  So I’ve added the obligatory snowflake to the 7 Day forecast for Wednesday night and Thursday morning.  Rarely does this pattern give us anything other than snow in the air and brief AM sticking snow in the lowlands, but sometimes we do a little better than that.  We probably won’t have a really good idea until at least Tuesday night as models key in on smaller scale features.  This is quite similar to the event in December that brought some morning snow to Portland’s West Hills and a dusting all the way down to sea level in spots.

Beyond Thursday it gets real interesting…

Earlier runs of the GFS had shown us drying out on Thursday with just a cool and dry air mass through Friday.  The 12z ECMWF decided to bring one more system down the coastline Friday for very cold rain and snow in the hills.  Now the 00z GFS has hopped onboard that idea bringing another wave of moisture south later Friday. 

What’s going on?  Models are having big issues deciding how close to build an upper level ridge to the coastline in the 7-14 day period.  If it builds real close to us, then mainly dry and fog/east wind.  If it’s a little farther offshore, weak and cold systems can drop in over us.  If it’s out around 145W or farther, that’s the perfect setup to “open the backdoor” for an arctic blast to move south.  Here’s an excellent example of the unknowns right now, the 18z GFS ensemble chart for 850mb:

tseries_850t_000-384_Portland

Look at the range on Day12!  The operational GFS was +9 (ridging quite close to us).  The warmest member was +13 and the coldest was -20 (bitter cold arctic blast).   Wow…the 12z ECMWF solutions were quite a bit closer:

tseries_850t_000-360_Portland

Although maybe 5 of the members were cold enough for snow, the general theme seems to be for ridging to get a bit closer (warmer).  Hmmm, I think we don’t really know yet.  Of course the 00z GFS just came out with a very cold forecast and a nice arctic outbreak around Day 10 (a week from Monday), but is it just one of the cold members?  We’ll find out soon when the chart comes in within a half hour.

10:02pm Update…and here it is!

tseries_850t_000-384_Portland

Stay tuned!

Chief Meteorologist Mark Nelsen

175 Responses to Snow, Freezing Rain, and Long Range Outlook

  1. pappoose in scappoose says:

    It certainly bears watching!

    National Weather Service Portland or
    324 am PST sun Jan 6 2013

    Long term…Tuesday night the frontal zone over Washington will
    gradually begin to shift southward. Strong low pressure moving into
    northern Vancouver Island will sharpen the cold front as it drives
    south across our district Wednesday. Expect one more period of decent precipitation Tuesday night/Wednesday before much colder air advects into our area. There is a chance snow levels will lower dramatically before precipitation tapers off behind the front. Models have trended a bit slower with the progression of this front…particularly the 00z European model (ecmwf)…
    which HPC has favored in their latest discussion. All models bring
    much colder but drier air into the district for the latter portion
    of the week. The 00z European model (ecmwf)/Gem are a bit further west than the 00z/06z GFS with the position of a strong upper ridge axis over the east Pacific…with the mean ridge position out near 145-150w. If this verifies…things could get interesting for the weekend as GFS/ECMWF/Gem all push a sharp disturbance southward from Alaska. The 00z European model (ecmwf) suggests a decent surface low tracking down the coast
    Sat/Sat night which could bring a threat for valley/coastal snow if
    it verifies. Not quite ready to jump on this solution yet…but it
    certainly bears watching. Weagle

  2. W7ENK says:

    Well, it looks like the 06z GFS was another bad run, following along behind last nights Euro. Just a glancing blow with the bulk of the really good stuff sliding down the back side of the Rockies… as per usual, this thing is now falling apart for us. :(

    Maybe we still squeeze out a few snowflakes (dusting-trace-1/4 inch) on the valley floor on Thursday, but then the ridge we wanted so bad sets up way too close to the coast, giving us average or slightly above temperatures, dry with possibly an inversion and fog. Not really a chance for East winds either, not with high pressure on both sides of the Gorge.

    A couple more consecutive runs like this and I think she’s done. We should know by tonight.

    4 years of this crap, we all knew this was coming… flip-flop, flip-flop, flip…

    • Mark Nelsen says:

      Yeah, but you are only looking at the “Flip” side, not the “Flop” side. You have to equally watch the flipping and flopping.

    • W7ENK says:

      Actually, missing out on the cold and snow IS the flop side, I want it to flip back to cold and snow, I don’t want this thing to flop!

    • Mark says:

      How come the models never get blamed for flip flopping?… That dies it! Models, you are complete flakes!

      I feel much better now, because these models get away with far too much, so I’m holding then accountable. ; )

  3. Well we finally may have a chance at a decent snow down here in the lowlands starting late wednesday really hope we can get some cold air into western washington to keep the snow around awhile. Listening to expert Rob it seems 50/50 right now could go either way. Time for us all to do the snow dance and hope the colder outlook wins the battle. We really deserve some snow down here been since last jan when we had good snows around here. Bring on the snow please snow gods.

    • Well, I dunno about all of that “expert” talk, I just try to provide my thoughts without stepping on any toes. I feel I have a decent-to-good grasp on a few things, sure, but an expert? Well… I do appreciate that though. Yeah, it’s up in the air for sure.

  4. lilfoot123 says:

    Happy Early Birthday! Mine was Jan 1st! I asked for snow on mine too! We got it in Cowlitz County on the 31st! Yes are wonderful presents! I like them kind of presents! We’ll start one at a time! Seahawks win 1st! Enjoy!

  5. JohnD says:

    This mornings Portland NOAA AFD long term discussion is extremely intriguing I must say. Isn’t Weagle (the forecaster) usually pretty good?

  6. bgb41 says:

    1/5/2013 Oregon (All) Temperature Summary

    Warmest:
    High:53 at DW8735 Yachats( 92 ft)
    Low: 45 at DW8735 Yachats(92 ft) & Port Orford(0 ft)

    Coldest:
    High:12 at NYSSA(2172 ft)
    Low: -14 at RED BUTTE (4460 ft )

    Largest Diurnal Change: 39 degrees
    FOSTER FLAT (33/-6 ) (5000 ft )

    Heaviest Rainfall:
    0.43″ at DW8761 Gleneden(72ft)
    0.43″ at W7KKE-3 Road’s E(89ft)

  7. Chris says:

    3 early birthday presents please 1st a artic blast 2nd Seahawks to win and 3rd a warm dry spring! A guy can dream right?

  8. swift says:

    The 00z Euro just made a statement and it’s not a good one. :(

  9. We all know this game. The good and the bad – The good thing is it is only 1 run. The bad thing is it could be a new trend. Oh and the other good thing is, the 12z runs tomorrow could very well bring back a favorable 500mb pattern. Oh and the last bad thing is, they easily could not too. You have to stay level headed and cautiously optimistic not worrying about 1 run versus another, but rather look closely at all of the runs for an entire day and ensembles.

    • Ben T says:

      Shouldn’t we also look how consistently cold it has been too?

    • Traci says:

      Why just once can’t it be easy??? So if, like you say, you look at all of the runs and ensembles for an entire day, what do you think?

    • I think things are leaning more towards a glancing blow with cold air filtering into Eastern Washington and the brunt of arctic air well east into Montana. However, that could be a pattern where a deep cold pool develops over the Columbia Basin(maybe even colder/stronger than the last one we just saw) and leads to another cold east wind regime. If so, that can lead you to possible overrunning situations like we just had, but in the past they also can lead to snow/ice storms.

    • Alan says:

      Hey Rob, thanks for the info. The glancing blow you mention refers to the end of next week or generally all of January? Accuweather (I know…) talks of very cold air mid month possibly begining in the northwest. Just courious if you’re speaking short term or long term. Thanks!

    • Oh, crap sorry I didn’t specify. I was referring to 7-14 days from now.

    • W7ENK says:

      Several things:

      1) ECMWF sucks tonight.

      2) It’s just one run, and with everything else following a sig for a good cold regime change, so

      3) It’s most likely a bad run, an outlier.

      4) Nobody panic!

      5) … Naah, never mind, that’s all.

    • Alan says:

      Thanks Rob. Appreciate your analysis. Please keep us arctic blast/east wind/snow lovers posted!

    • ocpaul says:

      “Slip slidin away, slip slidin awaay…you know the nearer your destination, the more you’re slip slidin away” Paul Simon

  10. 00z ECMWF

    http://www.cascadeaccess.com/~mnelsen/Models/ecmwf500mb_ecmwf.html

    ……
    Yuck. I wasn’t expecting it to be that bad… jeez. Only 1 run. Who knows, perhaps the operational could be an outlier. Ensembles later will tell the story.

    • Ben T says:

      How exactly do you read that map?

    • Benjamin (West Salem) says:

      Yes, seems to my eyes that the time period from the 12th through the 16th on the ECMWF tonight was far different than the last several runs.

    • Ben T says:

      Just comes down to which model you believe. I’m pretty sure ECMWF has been more conservative than the GFS throughout this whole thing. And I guess ECMWF is the most reliable one :( .

  11. EY (Oak Grove) says:

    Just had some decently heavy rain move through. Kinda hard to explain… Though the radar definitely said it was maybe a 20dBZ swath moving through, it was way heavier.

    Nothing impressive in it, thought there may have been like, 10% snow in there but I think my eyes are lying to me again.

    • W7ENK says:

      That’s weird, I’m just a short handful of miles from you and I didn’t get any of that. I just got back from a walk up to the store about a half hour ago — was outside maybe 45 minutes there and back total — and it’s just been a very steady light drizzle.

  12. geo says:

    Uumm. went from 3 poss. to 4.

  13. 00z ECMWF tonight will feature….

    Massive Arctic blast with reloads
    Modified Arctic blast via Gorge
    Glancing blow Cold pool Columbia Basin
    Cold pool Columbia Basin, Strong inversion

  14. Marcus says:

    Models are showing another disturbance dropping down for Friday! Maybe we can get snow out of that:)

  15. The way I see it there are 3 possibilities coming over the next 8-14 days.
    #1) Major arctic blast with at least 1 reload.
    #2) Arctic blast brunt into Montana/Northern Plains/Minnesota, glancing blow for eastern Washington, but enough for a strong cold pool to develop over the Columbia Basin.
    #3)Arctic Blast brunt into Idaho/Montana with a Modified arctic blast into eastern Washington, back door modified arctic push via Gorge, cold temps. Strong cold pool develops Columbia Basin. Right now I’d lead towards #2…

    • W7ENK says:

      I’ll take a Number 1, with extra snow and a side order of frozen over rivers please? And could I get that to last until February? Thank you!

    • Marcus says:

      Lol I’ll take one also!:)

    • Lurkyloo says:

      Supersize mine, please.

    • Mark says:

      The GSF and ECMWF – if the high moves further west, great. But if it moves east, flattens or moves inland, etc… we are toast with fog and warm temps w/mild inversion likely.

      My point? There are dozens of options, we still require the perfect scenario to fall into place. Odds?…

      Let’s give this another 48 hours to gel before getting too excited.

      I’m just trying to contain my Jr. High child from model riding too much and working himself up into an arctic apocalypse frenzy, which likely won’t pan out.

    • What about option #4? We go back into spells of rain, fog, little clearing, mounain snows? Slugs, mushrooms, mold, dry rot, mud puddle. Oh, and runny nose :)

  16. Marcus says:

    Ya I think the second half of this month is going to be cold!!!!!:)

  17. swift says:

    The 00z GFS at hr 228 is just SO SO SO SO CLOSE! In the meantime this Friday looks sweet for lowland snow, -8 to -10 C temps from PDX to SEA with a L sliding down the coast.

    • W7ENK says:

      Not really cold enough before the front, not a whole lot of moisture after the front. Models have backed off somewhat since last night.

  18. Jordan (Raleigh Hills, 420') says:

    00z GFS still looking quite cold and somewhat snowy. Wish we had more moisture to work with Friday while the cold air is very deep. We will see what ends up happening at the end of this coming week. Maybe the weekend storm will end up bringing us a good shot at accumulating snow. Keeping my fingers crossed!

  19. kdi says:

    3″ of new on top of our 10″ base. Woohoo! Looks like winter over here near maupin. Good stuff!

  20. WEATHERDAN says:

    At 6:45 PM here in South Salem we are getting sleet or ice pellets. The air temperature is 37 degrees, The winds are light and Northerly, with some breaks in the overcast. The current computer models may make me eat my words about winter being over. Which I will do gladly if we get an arctic outbreak. We will see.

  21. IceCold says:

    Just came through the gorge on my way back from Wenatchee. It was kind of strange. I expected places east of Cascade Locks to be worse, but the worst area was west of Cascade Locks….heavy snow about 10 miles outside of Troutdale. No ice…my prayers were answered.

  22. Marcus says:

    Nice, we will see! Wow tower temps are sure climbing good bye cold until Thursday.

    • Marcus says:

      Of course after I say tower temps are going up there they go back down:/ sleet and ice down south hmmm! Maybe some surprise snow showers tonight if tower temps keep going down! Or is there warm air coming in?

    • No moisture. There is barely any right now that aren’t surviving the coast range. Cold cloudy night on tap. Except for the Gorge.

  23. W7ENK says:

    Brian on KOIN just pulled the trigger.

    “I do think we are going to see some snow later on this week.”

    I do believe that makes Channel 6 the first? Mark, you’re off you game, man!

Follow

Get every new post delivered to your Inbox.

Join 296 other followers

%d bloggers like this: