December 27, 2021

Why Does Western Washington Have Some of the Worst Roadway Icing in the Country? And the Next Snowstorm in Sight

 Western Washington can brag about world-class coffee and leading corporations, but did you know we also have some of the worst road icing conditions in the nation when we get some snow?

Icing so bad that mayors can lose their jobs when they forget this meteorological fact?

Icing that can cripple parts of Seattle, killing and injuring both drivers and pedestrians?

Roosevelt and NE 75th Around 1 PM. ICE!

It happened again last night and today.  Let me tell you why.

Western Washington has a mild winter climate and our soils and roads cool down in autumn, of course, but remain well above freezing during the winter.

Then we get a snow event, with several inches falling on the roadways.  This snow starts to melt into a slush layer.

Next, much colder air comes in, as the low center and upper trough that produced the snow moves out.  The air temperatures become cold enough that the slush layer begins to freeze...and if cold enough (like yesterday today), it freezes solid to the roadway surface (and almost impossible to remove at this point).

The only way to stop this is to pretreat all roadways with a deicer (such as salt or potassium chloride) BEFORE the show falls and to remove snow after it falls, but before it freezes.   Judging from driving around Seattle today, not enough of both were done.  Many of the city's major roadways are not in good shape.

Another interesting aspect of this event has been the terrific steam fog produced over the Sound and other local water bodies.   When very cold air passes over relatively warm water, you can get tendrils of steam fog.

To illustrate, take a look at a video shot from the north side of the Kitsap Peninsula by Greg Johnson of Skunk Bay Weather.


The warm water supplies moisture that condenses in the cold air moving above.   Generally, you need at least 20F differences between air and water temperatures to get good steam fog.  With the Sound at around 50F and 20F air moving in, we had the necessary conditions.  Strong winds help the mixing and fog formation.  We had that as well.

The temperatures last night were exceptionally cold, with some areas around NW Washington dropping to UNDER 5F (see the minimum temps below).  

Seattle dropped to 17F. Some Puget Sound suburbs plummeted to nearly 10F.  Many daily minimum records were broken and this event as a whole is the coldest period in our region since 2010.


Thursday Snow?

Finally, there is the upcoming snow event on Thursday.  Both the UW and European Center models are going for several inches.

Here is the European Center 24-h snowfall ending 4 PM Thursday.  4-5 inches over Seattle.


The UW model for the same period is similar with some interesting differences (see below), with more snow on the coast and Seattle's snow reduced by rainshadowing.  As we get closer to the event, the forecast will sharpen up.




40 comments:

  1. How do euro and UW models differ? Different super computers or algorithms for prediction?

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  2. So glad you bring up the icy roads. I have a 2 wheel drive car and won't be able to drive anywhere until the snow melts in about a week. I had to walk 2 miles to a grocery store yesterday and load a backpack full of food because I was visiting my family in California and got back to an empty refrigerator on Christmas day. The snowstorm wasn't forecast a week ago when I left for California so I didn't think to stock up. Tomorrow I will walk 1.5 miles to a light rail station at 5 am because I cannot afford a week without work, productivity will be drastically reduced this week because many people don't live within walking distance of a light rail station. I grew up in a town in the foothills of the Sierra Nevada mountains. It didn't snow much but when it did snow the roads were plowed within 24 hours, waiting for the snow to melt is redicoulous. I understand Seattle doesn't want to invest alot in plows because it doesn't snow very much but the city needs to do better than this. The lost productivity would more than pay for a few additional plows as you have mentioned before. Normally I vote democrat but between excessive COVID restrictions and zero effort to clear my street are unacceptable and I will be voting republican for the next election or two.

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    1. It's not like snow is even that rare here. There are multiple weeks negatively impacted every year by our lack of a snow response. Why do we accept such a lackluster response?

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    2. First off...M, this is a general response that you sort of provided a good segue for.

      Do you mind paying more in taxes for a better response? SPOILER: Most won't.

      There has also been plenty of "Inslee fired all the plow drivers due to them not getting their vaccines" going around.

      First off, its still "The Holidays" and even blue collar people get to take a break once in a while to spend with family and friends. Christmas already seems like a Holiday that those who work for a living get the brown end of, so lets not further pour salt in the wound?

      Second, Inslee didn't "fire" anyone. Those who decided to put their convictions before the requirements of their work made that decision for themselves. Are we adults or not?

      Plus, it does not help that people can't drive safely around here on a sunny 75 degree day. Add in some bravado that comes with having a lifted F350 coal roller with mud tires and some give themselves a license to drive 10 over the limit on compact snow and ice. Removing the idiot factor or perhaps introducing a bit of common sense/restraint and it might turn out that the city's snow response is more than adequate. Even cities like Boston have to take the time and prioritize their removal efforts, but everyone is so entitled that a few days of inconvenience have them wanting the Mayor's head on a pike.

      Enjoy the snow. It really is beautiful. Its very rare that we get the snow and have it remain unspoiled for so long. If you don't have to go out, then don't. If you do, be careful and go slow. Everyone can drive in snow but how many can do so safely?

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    3. .... You're voting Republican because Democrats are trying to keep people from dying from a pandemic, and because you're inconvenienced by snow? Given the current Republican attitude and track record (perhaps educate yourself on their current in/actions and policies, or complete lack thereof- you know, the ones that go beyond that inconvenient snow) that's.... quite a decision. Wow.

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    4. Vote republican: then you won't have plows OR light rail haha.

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    5. Seattle can buy more plows but that won’t fix the problem. You have to train workers to operate the equipment which also takes skill and experience. But because it doesn’t snow that often and each storm is different, by the time you have the workers all trained up, the storm they train for doesn’t ever come and they are gone/off to a different career. So its really not the cities fault. I see plenty of plows out there. But you also have to plan on really good coordination with the drivers and office staff tracking the problem spots/communicating that to the plow drivers. A lot of coordination goes into this. More then just putting plows on the road.

      For us to sit behind our computers and blame this on republicans or Democrats is kinda crazy.

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    6. We don't need insanely high taxes to pay for snow removal. In California I paid about the same amount of taxes and snow was removed much quicker. You might think you pay less taxes than a Californian because there is no state income tax but Washington makes up for the lack of state income tax with a higher sales tax, other hidden taxes and various fees. For example I had to pay $300 to register my 2010 Toyota Corrolla a couple years ago when I never paid more than $150 to register it in California, I also never had to pay to park in the national forest or mountain trailhead in California. I don't expect all the roads to be plowed christmas weekend of course everyone takes it easy on the holiday. I'm upset because my road will never be plowed. I understand the republicans are worse argument but I also believe that if a party thinks they automatically have you're vote then they have no incentive to do anything for you. When a party makes a bad mistake one needs to vote for the other party in order to show them this is not acceptable/there are consequences to bad behavior. The republicans winning one or two elections won't destroy the state. California has a lower property tax than most states because when democrats increased the property tax too much the state voted republican and republicans put a cap on property tax.

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    7. Maybe buy a 4wd vehicle or a set of chains

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    8. I don't care which party figures this out: If you allow Americans to prosper they will generate tax revenues. You can use that to keep streets cleared, or you can let people buy the monster truck with the snowplow on the front and clear their own streets. Remember the Idaho teenager who made $35,000 in a week plowing parking lots and driveways during the 2019 Seattle snopocalypse? I used to live on a dead-end road in Whatcom County. We couldn't wait for government to rescue us. And it was Samaritan's Purse that came and did a lot of mudding out of homes here after the recent November floods.

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    9. Here's a very Republican solution for you so that you aren't dependent on government to do for you what you can do for yourself:
      BUY YOURSELF A SET OF CHAINS!
      With a relatively modest investment you would be able to get off that soapbox.

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    10. Actually, this response is "better" than what happened before. At least now the major arterials are largely passable. Anyone who remembers the big freeze of December 2008 knows even those were icy ruts for days.

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    11. So if California is so much better...

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  3. My observation about icing is that it also takes compression, either via car traffic or heavy pedestrian traffic on sidewalks. This morning I swept my front walk with a shop broom, and the very dry snow was gone cleanly, with no ice.

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    1. I am curious about this aspect as well as the statement that snow "melts" into a slush layer that later freezes to the road. Does that hold true when air temps remain well below freezing the entire time? Or is something (the roadway?) melting the snow? Is the compression the key factor? C'mon Cliff, let us know!

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    2. The friction of cars driving on the snow is enough to melt the top layers into a slush. More traffic = more slush, and then when the low-traffic evening comes through with colder temperatures, you can ice that has a much lower coefficient of friction and is much harder for a tire to melt back into slush.

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    3. This is why treating the road before the storm and plowing it during the storm are hugely effective and why most US cities do not have this roadway icing problem.

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    4. Most U.S. ciities don't have the creeks/streams and the Puget SOund to be concerned with.

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  4. Replies
    1. Easy for you to say if you have a 4 wheel drive, can work from home or you are on a salary. For those of us with 2 wheel drives the road might not be passable for a week. Like most people I'm paid by the hour if I take the entire week off I'd lose $1,200 and I don't get sick pay in my line of work. There is also alot of people that need to drive home from their holiday trip. People have been too isolated due to COVID I don't think we can ask them to keep canceling their holiday plans.

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    2. My 2003 toyota corolla fwd vehicle drives just fine in the snow. Sure its a tad light and doesn't have as good of traction as my 1996 4Runner, but blaming the vehicle is not always the answer. Just because someone has all the fancy gear doens't mean its impossible without it. Knowing how to drive in these conditions greatly improves your ability to use a vehicle of lesser status. Mine gets me to and from work without problems.

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    3. Couple of thoughts, reading along here:

      People get around just fine with 2WD all over the country where there are endemic snow and ice conditions on winter roads. The root of your problem isn't the snow and ice on the roads, but that you don't know how to safely drive under those conditions.

      Which isn't your fault, but it's also not anyone else's fault, either. If your life is really that dependent on your car, why haven't you taken steps to prepare for these entirely predictable conditions? You live in the Northwest; inclement weather should not come as a shock. It's like complaining about the power companies having to deal with storm damage--Did you not look at all the lovely trees surrounding your house, do the math, and realize that those trees are almost inevitably going to fall at some point, and take out your power? Would a mindful person not take steps to prepare for such occasions? Or, perhaps... Go live somewhere that daily life isn't subject to such vicissitudes?

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  5. I drove from the U District to Kenmore and back this morning and it was interesting to compare different responses. 25th Ave NE and Lake City Way in Seattle were mostly bare. Bothell Way in Lake Forest Park didn't seem to have been plowed or treated. Bothell Way in Kenmore seemed to have gotten more chemical treatment than plowing.

    Compared to 10 years ago, Seattle actually seems to do a reasonably good job of clearing major roads. Whether or not you can get to them from side streets is another story, of course. It also helps that Metro actually seems proactive about activating snow routes rather than the old strategy of "wait for at least half the fleet to have been abandoned on a 4% grade before considering switching to snow routing".

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  6. On June 28 when it was 108 degrees, I heard talk about how since that was five degrees hotter than it had ever been in Seattle this supported that global warming is increasing rapidly. However having a high temperature of 22 degrees which is 86 degrees colder almost exactly 6 months to the day clearly indicates that a 108 degree temperature does not in itself support that global warming is increasing rapidly.

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    1. You’re conflating weather and climate.

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    2. Don't think about climate change meaning across the board warming. It leads to climate instability, hence the extremes in temps. Some will claim extreme weather events such as the recent twister in Kentucky, but for that you must look at trends going back through the decades. There is no doubt the planet is warming (fart enough in an air tight room and it's going to effect the gaseous composition of the chemicals, even with natural mitigating elements). I think the push back against this accepted and scientifically uncontroversial fact is that some feel attacked for their lifestyle, or put on their political lenses, which happens way to often. The reality is we are undeniably effecting the climate, and the results will be variable and hard to predict.

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    3. Do you understand how carbon dioxide behaves in the thermosphere/mesosphere? Do you understand how a weakening magnetosphere impacts the amount of energy integrating into the global electric circuit? Do you know the difference Between CMIP 5 vs. CMIP 6? The sun impacts our weather much more than humans should be taking credit for, so please stop using old science to regurgitate corporate talking points.

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  7. As a N. Bend local did a quick hike up Mt Si today. Easily the most snow i've ever seen in over a decade from the valley to the summit and the finest gain snow granules, something one would usually experience in Montana, Colorado, Wyoming. Hoping that in Feb we dont see warmer temps/atmospheric rivers that would cause massive flooding with the amount of snowpack even at the lowest elevations.

    Most of the roads had the ice as you described. From what I understand they won't pre-treat the roads in N. Bend, Redmond etc. due to pollution concerns since those chemicals end up in waterways etc. Why can't they use rock salt like they do in the UK that turns the ice to slush within minutes?

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    1. Also a North Bend native and I concur. The most Snow I have seen in a decade and yes. This is powdery snow like in Colorado, not the usual heavy stuff.

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  8. Pretty surprised by the politically-charged nonsense comments that got approved here. I thought the 100% comment moderation was in place to avoid running afoul of 'no name calling or personal attacks'.

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    1. What did I miss? I do think that the attacks on Republicans were nasty, but I let it through to allow some political dialog. Republicans in our State certainly have a long history of caring about the environment...so claims otherwise are baseless.

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    2. The "I'm voting Republican next time" quip by Storm1...from that point forward the discussion turned nonsensical. "The state voted Republican." Blanket statement. No, a few percentage points swing to R isn't the whole state.

      Basically, neither side is really doing anything about the environment nor climate change because the costs will be paid by those who have yet to be born and there are still huge profits to be made now by exploitation. Plus, who's to say that those future generations won't just continue to kick the can down the road like many are doing today?

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  9. I'd much rather there be no road treatment. I can get around just fine with chains, but with the major roads cleared it's not possible to leave them on.

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  10. Bellingham has picked up a quick 1/2" this evening and it's still coming down.

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  11. Thanks for your offerings, Cliff.

    I wonder if it's possible to get a time-stamp on your Posts, so as to have a sense of what time of day your forecast is shared.

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  12. I observed a low of 14 degrees Monday morning here on the Bothell-Mill Creek line.

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  13. Here on Sinclair Inlet we seem to have gotten just a little more dusting of snow Monday night, or at least that is what the hummingbird feeder shows. Wind blown stuff? I have some non-critical medical things to do in Silverdale, but advice seems to be wait it out. If the roads are not clear tomorrow with Thursday snow, it may mean wait until next week. It is purty!

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  14. They just had a major freezing rain event in and around Fairbanks, AK. Likely the ice from that won't melt until March!

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  15. Well at least our carbon footprint will lower w less cars on the road and those gas-guzzling plows

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  16. Same people that claim we want salt and potassium chloride on the roads will be the same ones that whine when there in little to no salmon and bitch about the price of; and also claim that we should save the Orcas.

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Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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