Quick Evening Update

An extremely busy evening both on TV and off means my email Inbox is jammed…I’ll get to those later this week.

As mentioned this morning, models have come into good agreement and it’s even better on the new 00z runs.  More on tomorrow night’s big system in a minute.

This evening everything is going according to plan, a deepening surface low to the north is giving us a gusty southerly wind.  Temps are near their daytime highs as a result.  We just hit 36 at the station in northern Beaverton, the high for the day.  Our KPTV Tower temps have been rising since early afternoon and mesoscale models show the low level atmosphere maybe warming another 2 degrees by daybreak.  That mostly eliminates the chance for sticking snow at the lowest elevations.  One hitch is much heavier precipitation forecast to arrive between 7am and 10am.  This will be similar to this afternoon; heavy wet flakes will stick lower than they will tonight.  That’s why I said Trace-1″ at the lowest elevations by morning and 1-3″ up around 1,000′ and above.  The southerly wind may die down right around that time as well.

The rest of tomorrow looks similar to today temp & precip-wise.  With a light south wind we rise up to around 40 degrees, or at least the upper 30s. 

Good news for tomorrow night and early Wednesday morning.  All models now move the surface low up to somewhere near Astoria or a little farther north.  As the steady precipitation settles in after sunset tomorrow, the sticking snow level will probably be up around 1,000′.  Then a switch to light easterly flow between 10pm and 4am could allow the column of air overhead to drop to 32 degrees all the way down.  Model soundings are still showing this, just like I showed on the previous post.  It’s a very close call, but considering there will be no influx of cold/dry air from the Gorge, I’m not excited about a big metro-wide snowstorm.  I won’t be surprised if there is only a trace or less once again across the bulk of the lowest elevations from the Columbia River south.  I feel the best place to hold onto the cold air will be up against the Coast Range and then north of the Columbia River, up into Clark County.  Forget about it Salem…too mild down there (just barely).  The WRF-GFS and our RPM do not show accumulating snow in Portland, but it’s quite close!  Check out the WRF-GFS snowfall accumulation graphic valid from tomorrow at 4am to Wednesday 4am:

Once again, best chance north and west of Portland. 

Here’s the forecast graphic I used at 10pm for that period:

A southerly wind should move into here Wednesday midday at the latest.  Depending on the depth of the surface low, we could either have just southerly breezes or a significant wind event.  We can worry about that tomorrow.

197 Responses to Quick Evening Update

  1. PaulB/Eugene says:

    Down in Eugene…just rain or rain/snow mix this morning. Impressed that the temps are in the mid 30s even with stiff south wind…if it was just a bit colder it would have been a region-wide snow bonanza.

    This evening and tonight…I am taking a break from looking at the models, will need to rely only on satellite imagery, surface observations, 3hr pressure fall charts.

    The projected track of the low on the model runs does not imply that it WILL track that way…have to wait and see.

    Although the arctic boundary crawled at a snails pace down the Fraser outflow region, it regardless was an extremely sharp boundary…temps dropped 10 degrees plus with passage of front. Hope BC in the single digits.

    Probably an epic convergence boundary over NW WA (N of Everett at the moment)…six inches in 2-3 hours could happen.

    Windstorm? I have never seen 60mph gusts forecasted for the S valley without some lengthy discussion about it…I think anywhere from PDX to EUG needs to be concerned with this…it is not clear where this will happen..but if the low is still intact and not filling as it hauls off to the ENE…could have sudden jump in winds between 5 and 10am tomorrow morning,

    If there is sustained heavy band of precip tonight…could see snow to valley floor however I am skeptical of this. We would need precip rates of over .10 to .15 inches/hr…don’t think there will be sustained rates like this..yet.

  2. Tigard 225' says:

    I do not think we are going to get a snow storm or anything more than a few hours of slushy snow BUT, the Fraser river valley is getting its act together a bit now and the wind has switched in Bellingham, this will obviously have an effect on SEA:
    Zoom in just east of Vancouver, BC:

    • From The Weather Channel. . .
      “Since Sunday, snow showers have been falling off and on across the lower elevations of the Pacific Northwest. This wintry pattern will be capped off by a major, potentially historic, winter storm that will move across the region through Wednesday…….”

      I guess we’ll see, eh? Based on live streaming video from TripCheck (and comments from several family members in Tigard/Bull Mtn/Beaverton), there is snow falling but nothing really piling up. . . . Hope that changes for y’all down there! 🙂

  3. Hman says:

    We’ve been getting a lot of accumulation here in St. Helens OR. this morning. I’m @ 165′ acccording to the Garmin and there was 3″ to 4″ of new snow by 9am. Another shower just began.

  4. john says:

    when will the south wind die

  5. …10 inches and counting, snowing real hard, gusty winds from about every direction but south, 33.6 bouncing with every gust degrees…

  6. Nice looking Low pressure coming in mid to north coast on Thurs/Fri. Both GFS and NAM show that clearly.

  7. Taken by a friend earlier today

  8. John Clayton says:

    Mark, some forecasters are saying up to a foot of snow in Sandy throughout today and into tomorrow. Your thoughts on this, It has been snowing steadily since early am. A little wet right now but sticking slowly.

  9. Kyle Rose says:

    South Salem, been snowing for about 3 hours now…and it’s still really coming down. the ground is a sloshy 1 inch or so. very beautiful though…just a little wet.

  10. Yup….it’s the SCR hogging it all. Got 2″ overnight. Between 5&7″ depending where I measure. Will try post before/after pics later when the power quits flickering. I know, I know……gotta have pics 🙂

  11. Convergence starting to build in snow over eastside, 31.7f

  12. Jonny B says:

    I think every one has failed at predicting the weather in the gorge,
    especially NOAA and the NWS. There is no snow in the gorge any where at sea level. I am at 500 ft in Stevenson, and its done nothing but rain here since early last night, and cascade locks has been under a Winter Storm Warning since 8pm last night!?

  13. Switching from snow to a mix now. Game over 😦

    • Andrew (Portland....Sylvan Highlands ~800 feet) says:

      I have seen that “game over” mentioned every day since saturday haha.

    • This is the first day since Sunday that I have had anything but snow or snow showers. So it’s over for me. Maybe not for you northerners. Yet.

    • Dave in South Salem says:

      We had rain last night at 10pm and I can guarantee you its not game over

    • Dave, can we quote you on that 😉

    • Dave in South Salem says:

      I know I said game over last night so you can quote me… but I was wrong. Never seen a strong south wind cool off enough with onshore flow to turn back to snow. Well I did in Denver but not here.
      Denver does everything impossible including a snow shower turn around and come back to hit us twice and snow the same night it was 75 degrees and sunny.

    • Yesterday at one point I had sun, 39 deg, and light snow falling all at the same time. Cold air aloft, which is what we are losing. Unfortunately. BUT! The long range looks to get back to the goodies.

  14. Longview - 400 ft says:

    Currently 33.1
    1 3/4 of snow so far today.
    Low 32.5

  15. Jane - Forest Grove says:

    Any thoughts about strong winds (advisory level)in the metro area? Haven’t heard any discussion about that, usually when the coast gets hammered it’s a possibility. Especially out here.

  16. Rookie says:

    2 hour commute on the Sunset today. Yuk

  17. Danny(Milwaukie,OR) says:

    Here in Milwaukie, I’ve been seeing snow showers on and off, Switching from snow to light rain back to a stronger just snow shower. South wind still kicking, but stopping and have some wind also blowing from the East I’m noticing.

    • Yeah snowed almost solid for 2+ hours, but never got anything more than the cars dusted white. Raining for the last 20 minutes, might have switched over fully now.

    • Dave in South Salem says:

      Yes some of the gusts here have been coming from the east as well. The houses have snow stuck on the south sides and now it is sticking to the east sides

  18. Andrew says:

    I guarantee that there will be NO snow on the ground when
    We wake up tomorrow morning in Portland, Oregon.

    • Ron says:

      I agree, . . . sadly.

    • W7ENK says:

      Yup! I concur, whole-heartedly.

    • Dave in South Salem says:

      I thought for certain this would be the same where I live today. 34 degrees and strong south wind blowing last night and forecast was for temps to rise but lo and behold we woke up to snow. So its very possible especially if Mark says so.

    • W7ENK says:

      My temperature varied all of 0.9 degrees from midnight to 6:30am, with steady and constant rain and southerly winds. That’s not likely to change without a major surge of colder air, and that’s looking like less and less of a possibility as hour 0 approaches…

  19. pdxgeologist says:

    Warm air is winning the shoving match out in the Pacific…and are those pineapples?


    • David B says:

      Indeed, pineapples are coming. That’s why so much snow is being forecast in Seattle: Pineapple Express is forecast to collide with Arctic outflow winds from the Fraser Valley in our vicinity.

      Ample moisture + ample supply of cold air = prodigious snowfalls. But only in the zone where the two collide. Too far north and it’s plenty cold, but dry; too far south and it’s just warm rain.

      It’s what happened in 1996, when Seattle got one to two feet of snow. Most of that time, it was raining and in the fifties (typical Pineapple Express weather) at the same time Seattle was getting mega-dumps of snow.

      I rode north on Amtrak during the tail end of that event, and the transition was dramatic. Typical Pineapple weather (rain, 50s) through Centralia. At Olympia, temps had dropped into the 40s, but still just rain. In Tacoma, cold rain with some slush on the ground, mid-30s. By the time the train reached Kent, it was in the upper 20s, snowing hard, and a winter wonderland outside.

    • pdxgeologist says:

      Yes, and then it turned to rain everywhere and I spent the next 5 months criss-crossing Washington cataloguing landslides for FEMA. Rain on snow (especially alot of lowland snow) is not good – hope it doesn’t do that again.

  20. Marc (East Vancouver) says:

    Looks like Mark underestimated the amount of snow. A friend of mine at 1000 feet in the hills of Hockinson has already received 4 new inches of snow (still coming down hard) to make their total accumulation on the ground 9 inches. They are snowed in for the day.

    • Mark Nelsen says:

      I said 2-6″ in the hills around 1,000′ and above. That could end up being a little low (I’ve had 3″ since yesterday afternoon at 1,000′), but I think we’re doing fine so far. A Trace-1″ this morning in the lowest elevations is working out okay too.

      I’m real happy the south wind kept us above freezing too.

    • Marc (East Vancouver) says:

      My bad..I thought you said 1-3 on the hills. Could end being right on the money with 2-6 if it slows down.

      • Mark Nelsen says:

        Actually you read it correctly, I said 1-3″ overnight, and another 1-3″ today. Although I just changed it to another 2-4″ on hills today, the GOLU model at work. Still a little low though, I’ll give you that.

    • Ron says:

      He didn’t underestimate anything. 1,000 ft? Rules change a little. He was pretty much spot on. This is not an exact science where you nail the snowfall down to the inch. Sheesh.

    • homer55 says:

      I hope you don’t mind if I take minor offense to your being “happy” that the south wind kept us above freezing.

      I understand that this was important towards the accuracy of your forecast, but it was devastating towards my weather weenie need for snow on valley floor.

    • Hey Mark at 1600′ I had 7.25″ from 5pm last night to 630am this morning. I imagine I’ve had several inches since.

  21. David B says:

    Above-freezing temperatures with rain and mixed precipitation on and off through the night here in West Seattle. Sunday’s snow is now mostly gone.

    Waiting for the Fraser Gorge outflow winds to start kicking up and that low to suck them southwards to me. Winter Storm Warning has been issued for 6 to 10 inches here tomorrow.

  22. Ron says:

    0 accumulation with some glaupy rain, 35f at 320′ off of S. Fischers Mill Rd near Redland. 5 miles up Springwater Rd at 600ft, 1″ and beautiful snowflakes. Snow line is highly elevation sensitive and microclimates are very evident as some locations lower than me have some snow. I’m not sold with the maps that the low will track south enough to draw east winds (if at all) into the valley. Usually when its too close to call, it usually favors rain, not snow. IF it does snow down to the valley floor it will be very brief. Keep an eye on the KPTV tower temps tonight. Any warmup will be rapid.
    Mark has been spot on! He will wait to see later model runs this afternoon/evening before he commits. Wind patterns will be the key. I think the NWS has been once again premature. I hope they are right but except for just a few times in the last decade, these situations seldom spell snow down to the valley floor. I want snow but the NWS snow amounts are overblown for elevations down close to the floor.

    • Dave in South Salem says:

      And I’ve already hit the Weather Channel’s 48 hour snow forecast and this thing has not even supposedly started yet.

  23. Boomer in Vancouver (Near Van Mall) says:

    Finally a light dusting here in Vancouver, but looks like it is switching to rain as I write this.

  24. 1191BG says:

    have over 11-12″ on the ground, snowing heavy all morning and windy at 32.7 Most of the moisture is to be here this evening?! noaa says 7-11″ this evening for me so I am curious what tonight will bring…

  25. pappoose in scappoose says:

    Latest from the NWS:

    National Weather Service Portland or
    857 am PST Tuesday Jan 17 2012

    Satellite imagery shows a band extending southwestward from the
    olympic peninsula. NAM shows a couple of vorticity maximums in the area and brings them in this afternoon. So should see another burst of showers middle afternoon being enough cooler for some accumulations at the lowest elevations.
    Overrunning begins tonight. NAM brings a little stronger low than the GFS to near Astoria at 18z but the south winds not completely
    overpowering the cold air in the north interior. Will leave the
    advisories and warnings as is for the land regions. The Gorge will be the last of the low level zones to change from snow to rain if at
    all. Mostly likely upgrade winter weather advisories to warning on
    afternoon package and strongest winds Wednesday morning…especially the central coast.

    • alohabb says:

      Its getting real now…now we’re saying the snow level will RAISE to 500′ today….Gonna get real dicey tonight!

    • pappoose in scappoose says:

      I’m gonna ask the Magic 8-Ball what’s coming. A combination of that answer and what Mark tells us, will give us the best forecast possible!

    • Brad says:

      It’s not going to get dicey anywhere west of Cascade Locks and below 1,000 ft.

  26. jakeinthevalley says:

    Does anybody realize that a high wind watch is up for the valley for Wednesday?

    Gusts to 60, perhaps?

  27. Matt in Newberg says:

    Have about a inch on the ground. Snowing steadily and my temp is 32.6. Very slushy snow. Time to break in the new digital camera!

  28. Ben (Beaverton 775 ft.) says:

    Snowing hard…about 5 inches now!

  29. Mat the Salmon Killer says:

    I wonder what would need to happen in order for usɜ to get snow thru tomorrow? Would the low have to stall off the coast and just spin moisture at us? Orɜ would itɜ have to weaken enough so that itɜ just scoots thru the middle of the state? Does anyone know if something like this has ever happened here before?

  30. timmy - scappoose says:


  31. Camas mom says:

    Snowing crazy up here (Livingston Mountain 1,000 ft). School wasn’t called, kept my girls home because the road is just not safe no matter what crack smoking transportation director says. Looks like we get it all day long!

    Hope the low landers get a “surprise” few inches! I already told most of the boys, ima gonna call you out if you’re wrong this time! 🙂

  32. I have 7 inches of snow on the ground now and it’s still snowing pretty hard up here. Temp holding steady at 32.8, winds remain out of the N-NW

  33. Dave in South Salem says:

    Mark underestimated the latest forecast. Not only did it get colder overnight but we are at 1.5 inches at 500′ in Salem and its coming down hard. Does this mean he underestimated tonights forecast as well?

    • Steven 8 Miles E of Salem says:

      Me to its dumping right now i hope it dont stop…

    • Mark Nelsen says:

      Salem stayed well above freezing (in the city) in the mid 30s with a rain/snow mix all night. I hate to get defensive, but I think it worked out fine. More snow the higher up you go.

    • W7ENK says:

      Go back and read what mark said very carefully.
      He was dead-on accurate in what he said.

    • Josh Smith (South Salem 400' ) says:

      Hey mark

      that mid 30’s you have been talking about has been the north part and the airport, down south where Dave and I are, it have been holding around 31-32 degrees all night and this morning, with moderate snow coming down… finally let up, but from the radar looks more is coming, i just hope it doesnt switch to rain, i have seen that before,

      but currently 32 degrees, very light light flurries, about 1 1/2 inches on the ground,

    • Dave in South Salem says:

      Not trying to argue, but I have 2 inches now at 500′. That’s the 1000′ forecast.

    • Josh Smith (South Salem 400' ) says:

      thank you snow gods lol

      that next batch that i talked about, stayed as snow, and wow it is coming down, currently still 32 and snowing hard and the big flakes that are dancing around and getting tossed around by that wind, looks great outside 🙂

  34. lauriesylvan says:

    Do you think MSNBC is playing this up a little much?


  35. lauriesylvan says:

    Dumping big flakes right now. 2″ on the ground. 750′

  36. WhiteEagle - Garden Home/SW Portland says:

    …And the 12z GFS capitulates. Weakening low moves into Astoria.

    I’m thinking 4″ is now conservative, and when we do finally change to rain, there’s going to be a huge ice storm somewhere near the gorge.

    Game, Set, Match… Snowstorm. Enjoy, folks!!!

  37. gidrons says:

    6″ new snow this morning and was still falling hard when I left for work, at 1000′. An inch or two on the ground in the town of St Helens. It was funny hearing Rhonda on the radio saying no sticking snow below 800′. Rhonda, you had an extra 0 on that number. Take a cue from Mark before predicting snow levels.

  38. Tanya in Scappoose says:

    About half to one inch at the base of the hills in Scappoose and snowing heavily at 7:30am.

  39. stevied (North Portland) says:

    Sooooo close to a major dump of snow in PDX based on 12z WRF-GFS this morning

    • gidrons says:

      WRF sounding shows PDX snow from 1 am to 4 am.
      Euro shows PDX a little too far south for something big. Someplace between here and the border will get buried. My guess is Olympia/Tacoma area.

  40. W7ENK says:

    Erik Holm @W7ENK
    Hey @BigJoeBastardi, I had 8 mins of non-stick snowflakes total during your EPIC winter blast. Rain only in #Portland OR, where’s my snow?!

    In reply to Joe Bastardi
    7:57 AM – 17 Jan 12

  41. W7ENK says:

    Joe Bastardi @BigJoeBastardi
    Ideas on Pac Northwest snow.. coming true with vigor! However this pattern will break and is not as prolonged as 1950

    7:25 AM – 17 Jan 12 via web

    Really? Could’a fooled me… o_O

  42. chiefWright says:

    Snow/rain showers most of the time on commute from Marquam to Wilsonville. Snow sticking to fields starting about 1 mile South of Aurora. Snow sticking to pavement in a heavy shower at Aurora airport, but turning to slush.

  43. Wendy-Silver Lake says:

    Temp here is 32 but we lost a lot of snow last night. There are even some green spots in the yard. When I went to bed we had gained about two more inches, so don’t know what’s up with that. Kids are gonna be bummed when they get up. 😦

  44. Snowhound says:

    Big, big snow fall in the Beaverton area.
    Surface streets and slammed, Hwy 26 is a parking lot….

    Why am I at work??

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