Snow in the PNW 20-21: We may have Corona but Corona doesn't have us!

[Gunder]

I guess no matter what (whether or not we want to call it a PWL or just a possible sliding surface), when we get such large amounts of snow stacking up so fast, it's best to take a conservative approach as the snowpack adjusts to the added load. And luckily, burying such a crust layer deep enough (many meters down) should lead to a favorable situation for rounding over time due to reduced temp gradients.

Dont get caught up in the terminology. PWL do not have to just be facets, depth / buried hoar, etc. An ice layer is in fact persistent and it can in fact be a weak layer, so thus it can be a PWL.

Anytime you have a crust / ice layer in a snowpack near crust facets will form regardless of how that crust was buried. Water vapor is always moving up in the snowpack, crusts interfere with that and thus facets will start to form. Facets are also extremely strong in compression and can hold up a ton of weight before they fail. When that actually happens is anyones guess. Ideally we get enough rain to either force that failure along prematurely, or enough water to percolate down and saturate those facets and and then refreeze. Of note some of the biggest sides I've seen at baker involved a crust, where the snow came in correctly on top of it and started off being well bonded. Then it eventually failed months latter after a ton of snow fall. It is also worth noting, that typically in January we have a very stout crust form followed by a cold dry spell (January is usually high and dry here) then lots of snow usually buries it in Feb. So every major slide that has occurred (15+ feet deep) around the ski area has been with in the week before / after March 15th.

The current situation was made worse, sooner by the crust being buried by a layer that didn't stick to it from the beginning, creating a sliding surface that would reload and slide multiple times.

At the end of the day, one of the most dangerous things you can do is to "over think" snow science as anytime you think you can "out smart" a problem you will get spanked. The most important thing for me, when evaluating hazard is constantly asking what's going on thats out of the ordinary? Did we get a big loading event? Was there unusually strong winds? An unusual wind DIRECTION? A unusual dry period? unusual temps? unusual natural slide activity? The list goes on, but anytime anything unusual is on my radar, then I use a lot of extra caution as thats when "unusual" things such a slides, etc will tend to happen.

An unusual wind direction is a big one for me. Anytime a North East system comes in, which usually results in high-pressure we get very cold and very strong winds out. of the NW. That always scrapes snow off of the best ski terrain at Baker and then loads a lot of the terrain that is usually safe even on high avalanche danger days.

[jackattack]

10" of new under light to pissing rain at the windy hill this morning. Steep natural snow was velvety but in classic Mission fashion they sent the cats out in the evening on the only open chair worth riding, so it was 500 vert to 3" of garbage velcro mush on the "groomed" slopes. One and done for me and the missus, not worth a knee injury.

Hoping for percolation and consolidation of the pack.

[volklpowdermaniac]

Dont get caught up in the terminology. PWL do not have to just be facets, depth / buried hoar, etc. An ice layer is in fact persistent and it can in fact be a weak layer, so thus it can be a PWL.

Anytime you have a crust / ice layer in a snowpack near crust facets will form regardless of how that crust was buried. Water vapor is always moving up in the snowpack, crusts interfere with that and thus facets will start to form. Facets are also extremely strong in compression and can hold up a ton of weight before they fail. When that actually happens is anyones guess. Ideally we get enough rain to either force that failure along prematurely, or enough water to percolate down and saturate those facets and and then refreeze. Of note some of the biggest sides I've seen at baker involved a crust, where the snow came in correctly on top of it and started off being well bonded. Then it eventually failed months latter after a ton of snow fall. It is also worth noting, that typically in January we have a very stout crust form followed by a cold dry spell (January is usually high and dry here) then lots of snow usually buries it in Feb. So every major slide that has occurred (15+ feet deep) around the ski area has been with in the week before / after March 15th.

The current situation was made worse, sooner by the crust being buried by a layer that didn't stick to it from the beginning, creating a sliding surface that would reload and slide multiple times.

At the end of the day, one of the most dangerous things you can do is to "over think" snow science as anytime you think you can "out smart" a problem you will get spanked. The most important thing for me, when evaluating hazard is constantly asking what's going on thats out of the ordinary? Did we get a big loading event? Was there unusually strong winds? An unusual wind DIRECTION? A unusual dry period? unusual temps? unusual natural slide activity? The list goes on, but anytime anything unusual is on my radar, then I use a lot of extra caution as thats when "unusual" things such a slides, etc will tend to happen.

An unusual wind direction is a big one for me. Anytime a North East system comes in, which usually results in high-pressure we get very cold and very strong winds out. of the NW. That always scrapes snow off of the best ski terrain at Baker and then loads a lot of the terrain that is usually safe even on high avalanche danger days.

I love your takes, and if I’m reading correctly your general gestalt, I totally agree. I worked in the snow for many years prior to moving in a different direction and had many excellent teachers, but one who stood out was the one who always taught to not get bogged down in the minutia of snow science. Look at the big picture, simple stuff and you can stay alive a very long time. When I was back in my formal AIARE days I always thought that there was too much diving into the snow science, which while great! I feel like is often hard for layman to use effectively and simply. Maybe there is a new approach being used.

[MagnificentUnicorn]

10" of new under light to pissing rain at the windy hill this morning. Steep natural snow was velvety but in classic Mission fashion they sent the cats out in the evening on the only open chair worth riding, so it was 500 vert to 3" of garbage velcro mush on the "groomed" slopes. One and done for me and the missus, not worth a knee injury.

Hoping for percolation and consolidation of the pack.

I can’t believe you put your boots on


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[jackattack]

I can’t believe you put your boots on

gambled and cut our losses.

[wickstad]

gambled and cut our losses.

I stood there for awhile. Went home injury free.

[cascadianwarrior]

I did 3 laps in the trees off 3 (which were pretty decent) but yeah, as soon as you hit the groomers it became glue. Easy call to pull the plug on the day

[Dromond]

Good post about this from a southern neighbor (post 842 in the Oregon thread):

This video I just saw posted on near crust faceting seems relevant to the discussion:

[kamtron]

Thanks for the video! About 10 min in he talks about possible outcomes in a maritime snowpack.

Here's some stoke for you all. First picture from Dec 23, one day after a solid rain event, a good day for facet atop crust surfing.

[Dromond]

...crickets..... well it's at least sunny?

[ridinshockgun]

Surprised there isn't more from Saturday coming in.

[greenmachine]

no shit! keep em coming.

[Skis]

Any idea how the crowds have been with COVID rules at each place? Mostly thinking midweek, but probably end up doing a couple weekend days too. Other thoughts?

[NW_SKIER]

Weekend days? You must like lines.

[AK47bp]

Any idea how the crowds have been with COVID rules at each place? Mostly thinking midweek, but probably end up doing a couple weekend days too. Other thoughts?

Totally!


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[The AD]

Any idea how the crowds have been with COVID rules at each place? Mostly thinking midweek, but probably end up doing a couple weekend days too. Other thoughts?

If you don't like lines head up for night skiing. Obviously that limits the terrain options, but you can lap to your heart's content.

[timeo]

My Crystal experience so far: lines are longer on weekends but not by much. In a normal year, midweek would have zero lines but now they are about 75% of what the weekend lines are so it isn't a huge benefit going midweek. Lines are significantly smaller after around 2PM or so. Also, depends a lot if all lifts are running or not, windhold = huge lines.

Every midweek day I have skied this year the parking lots were filled into F lot.

[Dromond]

My Crystal experience so far: lines are longer on weekends but not by much. In a normal year, midweek would have zero lines but now they are about 75% of what the weekend lines are so it isn't a huge benefit going midweek. Lines are significantly smaller after around 2PM or so. Also, depends a lot if all lifts are running or not, windhold = huge lines.

Every midweek day I have skied this year the parking lots were filled into F lot.

I concur, although maybe on one day I skied the G lot didn’t fill. It’s been busy for sure.

[jacob_dbu]

I would say COVID-19 restrictions are much tighter at Crystal than Stevens. Crystal has lifties running the lines but at Stevens it was a lot easier to casually pair up. Also, mask enforcement was much stricter at Crystal where they yell at you constantly whereas my experience at Stevens (only one time) is that when you get to the ropes for the lines you should pull your mask up but its more casual and less yelling.

Don't mind either way, but lines seemed to move faster at Stevens.

[timeo]

I will also add that the singles line moves twice as fast as the other lines on Rex based on how they have been loading, they have just been taking a group from each line on Rex which means they take two singles each pass. This is the only chair that works this way because it has one single line vs. two single lines at the other chairs.

[nickwm21]

I will also add that the singles line moves twice as fast as the other lines on Rex based on how they have been loading, they have just been taking a group from each line on Rex which means they take two singles each pass. This is the only chair that works this way because it has one single line vs. two single lines at the other chairs.

As a single you get fucked during the morning rush on Chex. They don’t load a singles chair like they do on Rex.... it will take 2-3 times longer to load than a group of two...


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[phatty]

Posted this in the Alpental thread, but Snoqualmie reposted Thing #2 getting huge at Alpental.

https://www.instagram.com/p/CKEek2sh...d=gssic473fsa6

[snoqpass]

Mission Ridge has it going on after the lifts close

[AK47bp]

Mission Ridge has it going on after the lifts close

And powdered snow.


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[wickstad]

It got real busy there for a while.