A Very Icy Morning! Most Areas Melt This Afternoon

10am Friday…

A solid line of liquid rain moved over the metro area during the night, falling into the sub-freezing air.  That left a glazing of ice for most of us for the morning commute.  It wasn’t a lot, but as I’ve mentioned many times in the past, it only takes 10 minutes of that freezing rain to make a road very slick.


As of this hour temperatures are ever so slowly creeping upward.  More important, road surface temps are all at/above freezing except east of I-205.  That means the additional rain now moving into the metro area will actually help get the ice off the roads as we head into midday.  During daylight hours, anytime the air temperature goes above 30 degrees, the “extra heat” we get even through cloud cover allows pavement temps to go above freezing.  I remember first noticing this effect during an ice storm around 2006 when reporters were saying the road/sidewalk was melting even though it was 29 degrees.  Of course at night it’s a different story, but even during nighttime icing events main roads don’t tend to see icing until it’s down around 30.

To summarize:

  • We’ve seen the worst icing on roads already; all areas except the high parts of the West Hills and areas east of I-205 will see dramatic improvement in road conditions through the rest of the day.  The evening commute will be almost normal except close to the Gorge.
  • Any area still at 32 or below will continue to see ice glazing on trees/powerlines and other objects through the afternoon.  Of course once your temp goes above 32, it’s over for this event.
  • There will not be any re-freezing of roads tonight, temperatures will warm through the evening and overnight as a milder south wind takes over.
  • Near and in the western Gorge road conditions will go downhill with fresh glazing midday/afternoon.  Things won’t improve out there until tonight and Saturday AM when the east wind disappears and warmer southerly wind arrives.  That wind switch should arrive around 1-4am
  • Saturday we’re totally clear with regular rain…and quite a bit!

Chief Meteorologist Mark Nelsen

104 Responses to A Very Icy Morning! Most Areas Melt This Afternoon

  1. JohnD says:

    I am trying really hard to understand the nuances and complexities of the imminent pattern. It is just that it is so rare to expect any kind of low elevation winter weather event without the Gorge component. No doubt this will be a cliff hanger until the end. I have officially begun my personal watch and records keeping as of last hour–which I plan to sustain through at least Tues. Hopefully it is filled with a lot of fun stuff–along with a great winter wonderland urban hike and a bunch of shoveling! After that, thoughts will hopefully turn to spring. 46.4′ here in inner SWPDX at this hour.

  2. High Desert Mat says:

    Whatever happens there will be a lot of annoyed people on both sides. That’s my prediction.

  3. Sapo says:

    It’s becoming clear that this event will probably come down to just a degree or two. This can really be shown with the 12z WRF today…10 AM to 10 PM we are literally right on the edge of sticking snow, but we are just a degree or two too warm for a massive snowstorm.

    NAM 4km and 3km both show us being cool enough, and drop huge totals. RPM shows 12.7″, so we’re cold enough on that run. It’s really going to be a GOLU event. As Shawn Weagle mentioned in the AFD, some areas may get a ton of snow and some areas not much, depends when we cool down to be at or below freezing.

    Although the GFS operational hasn’t been on board at all, the GFS ensembles look snowy and Euro ensembles super snowy too.

    • Joshua Downtown PDX says:

      Yep. It’s either a foot of snow or a ton of cold rain.

    • john.fairplay says:

      If history is our guide, the WRF is likely right, but this winter has confounded even the smartest computer model. Very much looking forward to some kind of surprise temperature drop.

  4. Scooter says:

    I suppose I’m just getting too old for this blog stuff. I keep reading wish casting, and criticism of models that don’t provide information that supports wish casting, unreal expectations etc. Back in the day we accepted weather as it came and most folks took what ever happened in stride. I guess times change people and we have a more finicky, tech driven and highly expectant society.

    • Registered Nerd says:

      I agree with you to a point, I mean we are truly in a instant-info tech society where patience is definitely lacking…. But on another level, what else is this blog for Scooter? It’s enjoyable to look at weather sequences and how all the little parts come together to create an interesting weather outcome. I don’t understand why you would get so annoyed with other people’s enjoyment of that. I do understand how you might be annoyed if people are demanding a 100% accurate forecast on these very unpredictable events days in advance…. That annoys me too. But for the most part that’s not happening on this blog and you just need to relax or not read the blog. Just my thoughts.

    • Diana F. says:

      I agree our society is incredibly, ridiculously tech driven and expectant, heck even entitled, like never before. I personally see the “selfies” craze as ridiculous, an actual scourge of our society! I read the other day that the inventor of the digital camera HATES what has happened with his creation…..and would take it all back if he could.

      But I don’t necessarily agree that’s what’s going on in this blog. I see most participants as highly appreciative of the forces of nature. In awe, really. And these sorts of “wish-casting” events are just that. Wishing. Hoping. In the end, our opinions mean nothing to Mother Nature, and that’s a fact.

      But we do love winter weather, and it’s such great fun to get it on occasion. The models & reports are the ONLY thing we have to help quantify, and define, our obsession. We look at them, decide what we think, and make our comments. Based on our opinion. Well, all that and Mark of course : )

      Of course we take the weather as it comes. Is there any other way?

      Most of us are simply grateful the sun comes up every day, day after day. The rest is just frosting on an already great cake.

      So if the wish casting and complaining bothers you, then perhaps this blog is just no longer what you’re looking for……and that’s ok too. We’re all just people trying to make our way in a complicated world, and I actually think weather is something that brings us back to a simpler time. Is it, or isn’t it is what it comes down too. Because in the end, it does what it’s going to do, no matter what we think or say : )

    • Longview 400 ft says:

      I agree with Registered Nerd. Before Computers, Windows and all that, I paid attention to Jim Little at 5pm and 11pm to get my updates and fixes on the upcoming weather. Then when Jim left KOIN 6, I went with Rod Hill to Mark Nelsen for those updates because that was the cutting edge of the best at the time and now present could offer.
      I enjoy this blog for several reasons: to read what Mark thinks and what others do as well. Yes, some posts are ridiculous but many others are quite interesting to ponder. Another is to keep somewhat aware of any potential hazards that affect my family’s safety in immediate future to avoid those hazards. Just like yesterday morning on I-5. Also, our driveway is very steep and have to park down the street so as to be able to go to work or whatever.
      We all have different passions that interest each one of us. A passion for the subject of weather naturally draws those of such passion of understanding and learning here at this blog.
      Mark also is usually right on when it comes to the DETAILS of what is going to happen weather wise. Why else spend ones time here?
      So when other people post on the blog about their weather thoughts or ideas why not?

    • JF says:

      I agree as well. But I will say that wish casting has and will always be part of a forum like this. I personally have always found this blog to be an outstanding source of information. It is up to each individual to interpret it within their own parameters. It would be great to get people like Paul from Eugene back on board.

    • JF says:

      As a matter of fact, wish casting based off of legitimate models and outside possibilities can be fun to contemplate and at times these scenarios have actually played out.

    • Windsday says:

      Trump is out to change the global elite and screw them. Get rid of our bloatware government to where it is needed the most. National Defense and our infrastructure.

  5. Marc (Brush Prairie, WA) says:

    Still no update?? Time is ticking. If it is an event, it will be here soon.

  6. Alohabb says:

    I don’t think I’ve ever seen the NWS AFD mention 18″ of snow in PDX based on a model run! Holy smokes!

  7. Josh says:

    OK I’m new to all this but i see allot of people talking about the snow totals for Portland. Amy idea on possible snow amounts for Sandy Oregon. Thanks

  8. marinersfan85 says:

    6Z nam burries Portland with 18″

    • Alohabb says:

      Insane to see models doing this so close to the event. Usually we get these insane amount 7-10 days out.

  9. Hali Mendez says:

    I can’t believe we we’re looking at the possibility of more snow Sun/Mon. If I wanted weather like this I could have stayed in MN! I’m so done with winter.

  10. Doubtless the relocated Dome will keep it all away from me until Tuesday. Why Tuesday? I have a flight scheduled then.

  11. JohnD says:

    Cliff Mass’s hot off the press blog tonight shows Portland as the sweet spot. The only hedge–marginal temps. We’ll see. Sure pulling for this. Epic potential–but, as always, braced!

    • Mark says:

      This shoes is one of two things:

      A. What an amazing snow storm is approaching


      B. How bad snow models still are for our area, even though it is 2017.

      Can we put metal in microwaves yet?…

  12. marinersfan85 says:

    Mark! Your thoughts are needed!!

    • Mark says:

      Mark will post when he’s pretty locked in on what is going down… with no mentions yet, to me this is an indication it is still a coin toss…

  13. Hopefully the roads between The Dalles and White Salmon are not buried between noon and 10pm Sunday! My current definition of “butthurt” is having to miss the Superbowl/Imbolc potluck because of unexpected snow…

    • marinersfan85 says:

      Hopefully the,roads are burried before 10pm sunday. Ideally around 2pm just after the transition.

    • Mark says:

      Well, if it is unexpected snow that causes these issues, just consider it expected snow, and everything should be fine then. ; )

  14. Sapo says:

    00z recap so far (minus Euro since it hasn’t run)
    snowy runs:
    RPM: 10″
    WRF: 8-10″
    NAM: 10-14″

    not snowy runs:
    GFS: trace-1″. the issue here is surface temps. models like the WRF probably handle this more correctly. if the GFS was a bit cooler it would be in the 6-10″ camp or so.

    GEM: nothing. the problem with the GEM is low track.

    As far as when we transition, it appears the transition comes between 1 and 4 PM for snow in the air, and sticking snow really starts around 4/5 PM as we cool down to freezing sunday evening. also it might just rain, who knows

    • Timenators says:

      where in the “heck” is the updated AFD?? Get out from under your desk and right it up! Lets go people

    • boydo3 N Albany says:

      It’s a crap shoot..

    • Mark says:

      Mark Nelson knows, but he isn’t sharing – yet!

      Actually, he may not know and is biding his time as best he can, as this is a very difficult forecast.

      I would lean with the GFS – I have seen it snow in Portland for hours, just to watch it all melts as it hits with 34 or 35° and wet snow. We rarely get sticking snow from this trajectory of storm with no east wind involvement.

    • marinersfan85 says:

      In this situation, almost no wind is what we want.

    • Sapo says:

      Yeah we don’t want wind in this setup. Allows for the cold air to be pulled down more effectively, we want it to be calm for better snow chances in this setup.

      this setup can happen, just pretty rare. march 2012 is the most recent example i can think of

  15. Sapo says:

    Anyone see the 00z NAM? 10-14″ of snow. It very well may not happen but that would be epic

    • Sapo says:

      Although as someone pointed out to me previously, this would be heavy wet snow and the 10:1 ratio may not be totally accurate, so maybe 8-12″ amount would be more accurate for this run

    • Jake-(Gresham near Nadaka Nature Park) says:

      I’ll look at it right now!

    • Jake-(Gresham near Nadaka Nature Park) says:

      …… Yeah….. so um the GFS was also showing the same pattern of moisture into the valley.

      I believe it’s time we all purchased these:

    • boydo3 N Albany says:

      GFS is not as cold at the surface. But who knows? We had the same thing happen 3 years ago Feb. 8-9th and the mid Valley got hammered with a foot and a half of snow. It also happened March 21st 2012 with 9″.
      (sorry Portland)

    • boydo3 N Albany says:

      A lot has to do with the winds at the surface and how hard the precip is when the two air masses collide. If the cold air can slip down while the rain (snow above) is pounding down then…KABOOM! air column stays cold enough all the way to the surface and the snow piles up!

    • Jake-(Gresham near Nadaka Nature Park) says:

      Yeah that’s critically important. What I find encouraging is the vectors are showing not only East to West but also North to South (again from the 200mb to the 850mb). That would allow for excellent mixing and great precipitation. So no signs of West to East or the worst, South to North.

      We may see a transition to snow as early as noon Sunday if the next model runs stay the same or better yet, show titer consolidation (I know you know this; just being rhetorical for others). Personal view on this, I’d say it’s looking good in my eyes in the right direction for snowfall from Sunday 3pm into Tuesday.

    • Joshua Downtown PDX says:

      00z RPM is going with 10″. I wish I had access to all the Euro maps. Mark?!

  16. Jake-(Gresham near Nadaka Nature Park) says:

    I’m not seeing a South wind for Saturday. No wind vector signs indicating any change from the 200mb Heights to the 850mb both on GFS and Euro.

    This is turning to be beastly in nature.

    I haven’t seen so much cold packed into BC in some time. Solid purple the entire Providence. If that low starting off Vancouver island drops a little South? That is how a blizzard happens West of the Cascades…..

    I have never see some much cold pool off Vancouver island. Looks like fist about ready to punch Washington and Oregon!

    • Jake-(Gresham near Nadaka Nature Park) says:

      seen* )_)

    • Jake-(Gresham near Nadaka Nature Park) says:

      seen so* (_)

      I need to step away from the models. It’s too much! Hahaha! 😛

      Long range models also indicate a mean looking polar vortex in the North East spinning off all this cold later in the week. Intense stuff. The dead of Winter type.

    • Mark says:

      Can Boss Plow be retro-fit onto a Mazda6, with really poor FRD traction?…

    • Jake-(Gresham near Nadaka Nature Park) says:

      I’ll grab the duct tape. Practiced on my car. Very qualified for this now. 😛

  17. W7ENK says:

    It’s still super icy in Downtown Portland. Thankfully the roads and sidewalks are just wet.

    Photos coming soon…

  18. Diana F. says:

    Yes I’d say it’s a bit of the unknown coming up on Monday—Rain or 10+ inches says Brian!

    “Sunday will be very interesting. Sunday likely starts off with light rain and at some point, it could transition to snow. Keep in mind, we could see just cold rain, or we could see 10+”.

    Oh I will DEFINITELY keep that in mind.

  19. JohnD says:

    Is it possible that we don’t get a southerly push on Saturday after all? And if not, does this further enhance the winter storm potential for later Sunday-Monday? This is such an incredibly active and complex “pattern” that we are in; I honestly don’t how Mark and others can keep up!

  20. W7ENK says:


  21. Josh "The Snowman" from Gladstone, OR says:

    Key to the next 72 hours is suppression of the southern jet. Models have already screwed up today’s low track. Let’s see if we can get the trough off the aleutians to dig properly. Where is rob? This is a great water vapor loop tracking evening.

    • Scooter says:

      What are you smokin’ there “Frosty”? Please tell us how a model can screw up the weather, and the last time I checked we can’t do anything to move troughs (properly or not).

    • muxpux (Longview) says:

      I enjoy nothing more than smoking a bowl of some fine weed and zoning out on the water vapor loop. So pretty and so much to look at. You can really get lost in it.

  22. W7ENK says:

    Got about 15-20 minutes of heavy sleet yesterday around 5p in Milwaukie, just enough to make the ground silver and crunchy. East winds slacked a bit and the sky cleared off just after sunset, the temperature dove about 10 degrees before the clouds moved back in. East winds picked back up really strong about the time I went to bed last night.

    Woke up to a solid 1/8″ glaze of ice on everything, including the road surface, still raining. This would be why I chose to email my boss, crawl back into bed and go back to sleep for another couple hours:

    Tried again at 8:30a, everything was still iced over — about 1/4″ thick. Decided to abandon my car in the driveway and carefully walked up to the bus. MAX was AFU (I should have known better), waited for almost an hour watching the icicles grow.

    Still icy in Downtown Portland at the Noon hour.

    And here it is, almost 3 in the afternoon and the icicles in the trees out my window here at the office are still hanging on, still growing! Whadd’ya wanna bet this all refreezes on the roads tonight?

  23. Diana F. says:

    Gotta love the NWS : )

    “……heavier rain band depicted by the models, indicates diabatic cooling resulting in snow levels potentially lowering to valley floors from late Sun into early Mon. Would still like to see how later model runs handle this situation before diving in head first, but for now will lower snow levels to allow for a low elevation rain snow mix through the lower Columbia and into the North Willamette Valley. If the models are correct however, there is the potential for a quick few inches of snow Sun night.
    So, enough about all that could go wrong with this forecast….”

  24. Scooter says:

    OMG!!!…..17 inches of snow on the valley floor…..this is going to be one heck of a mess……forget the road salt better issue snow shoes….then row boats…stay tuned…can you imagine all the drunk drivers after the Super Bowl trying to navigate….hope they get all this on tape!

  25. Mark says:

    I see nothing about Sunday/Monday… I know this is going to be a very tricky forecast, so I get the idea of “Let’s talk about the ice storm right now, because we don’t know what will happen in two days…”

    The incoming event could be a massive heavy wet snow event, or an extremely close call. From everything I am looking at, it’s looking like a decent wet snow system hitting us.

  26. Josh "The Snowman" from Gladstone, OR says:

    7 day already changed.

  27. Alohabb says:

    OH NO HE DIDNT! Did bmac just show the model for 7″ of snow this Sunday !!

  28. Diana F says:

    Links to the Sunday Snowmageddon please! Not seeing it anywhere!

  29. Josh "The Snowman" from Gladstone, OR says:

    The potential for Sunday night into Monday is looking better than anything so far this winter IMO. Precipitation rates are going to play a huge part. March 2012 is a great analog plus it’s a month early 🙂

    • Joshua Downtown PDX says:

      The 12z NAM gives PDX 17″ of the white goodness. Ho Lee Sheet!

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

      May as well snow 17″ as it is 2017! Speaking of, or not speaking of….What is going on that we are on the edge of snowmaggeddan, and don’t know it yet from our top peeps? Sorry, not picking on you Mark, just wondering why I keep hearing storm of the Universe from everyone else, including Steve Pierce, and not from you? Please dispel/confirm these myths when you get a chance, your minions are waiting….

    • Sapo says:

      Details still need to be ironed out, but it’s likely we see snow. Curious to hear Mark’s thoughts…I’m thinking he will post after 00z runs tonight, but who knows

  30. chiefWright, Marquam (350') says:

    Picky science detail, but an important one:

    The dry-bulb temperature was ABOVE freezing in most locations (specifically KPDX, KUAO & KHIO) when the precip rolled in this morning.

    But the wet-bulb was well below freezing. Before the precip hit the ground, the dewpoint started to climb because the rainfall was evaporating into the dry surface airmass instead of making it to the ground.

    And as the dewpoint climbed, the air temperature dropped. And the rainfall probably got super-cooled to below freezing, but still in liquid form when it hit the ground. All due to evaporative cooling.

    Some places only had glaze on cars & decks & the like. But it all depended the starting air temp and amount of evaporative cooling. Air temp up at Capital was hovering right at freezing this morning, so the ground temp tipped below freezing when super-cooled rainfall hit. Result? Pileup on I5!

    I was thinking it would be a complete non-event this morning based on the much warmer surface temps than forecast, but I should have given more consideration to the wet-bulb.

    LOVE science!

  31. Marc (Brush Prairie, WA) says:

    You had to have left out Sunday as a tease or to buy time….

    • Sapo says:

      I don’t think anyone wants to jump the gun on this one. Could be plain rain, could be a huge snowstorm (looking more like the snowstorm).

      Lots of details to be ironed out

    • JJ78259 says:

      This winter must be Weather Dan’s worst nightmare no warmth just cold and more snow! It would be cool to see Portland get another 12 inches of the white stuff Sunday! This could be the best winter ever if that happened!

    • WEATHERDAN says:

      All Winter long I have been posting about how much I have been enjoying the snow. One last time for those who don’t pay attention. I love hot Summers in Summer and cold Winters in Winter. Of the two I prefer Summer but I am enjoying this Winter very much thank you. Peace.

  32. Roland Derksen says:

    Snow here has changed to light snow grains with the temperature around 32F. I measured 2 inches from this morning’s action, which started around 6:30am. More snow is forecasted later today here in Vancouver(BC).

  33. Lawlessness Brings Destruction says:

    Is anyone there?

  34. Sapo says:

    Sunday is going to be interesting. Soundings indicate we may switch over to snow anywhere from the morning hours to late evening.

    NAM switches us over early and thus gives us 8-12″ of snow, WRF during the evening hours for 3-5″. Euro is more like 10 PM, but still a solid 2-4″ snowstorm.

    I think that with the heavy precip rates being modeled for Sunday and chilly upper air temps could bring snow all the way down to the valley floor earlier than modeled. It will be a tough forecast..

  35. marinersfan85 says:

    Still no mention of sunday!

  36. Paul D says:

    No more wind!

  37. Mama Druid says:

    I’m amazed at how many people seem to think driving on ice is no big deal.

  38. Andrew says:

    dp’s still in the mid 20’s, temp are falling as precip enters, could get bad. PDX at 32/25, Sylvan back down to 29.

    • Lawlessness Brings Destruction says:

      I work in the Parkrose area and commute from NE 162nd & Burnside. Will I be able to get to my 3pm-11pm shift in one piece?

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