April 21, 2019, Birthday Tour + Copper Pass (+Avalanche)

4/21/19
WA Cascades NE
2533
4
Posted by Onward. on 4/21/19 2:16pm
Partner and I just did some skiing around the route of the Birthday Tour over the last 2 days in Copper Valley. We basically did the birthday tour but spent the night in the valley and picked nice lines off a variety of aspects with the extra time. The riding in Copper Valley was outstanding (mostly, see next paragraph). The Early Winters Creek exit was a horrible mix of avy debris and crust at 3:30pm.

As we were ascending a slope in the early afternoon on day 2 we triggered what I consider an odd avalanche for the PNW - a remote triggered wet slab. It carried my partner about 50' downhill and his pole is still up there somewhere. Turns out there were at least 2 other similar slides this weekend submitted to NWAC. Be careful out there. I'll be reflecting on this one, but we observed almost no red flags including no slab avalanche activity at all and no wet slide activity, except for wet slide debris that looked 2-3 days old from this week's midweek precip (including no active rollers or pinwheels in 2 days of skiing). I say almost no flags because we did observe one small localized collapse of about 2" on low angle terrain - no audible whumpf, but enough that we stopped for a moment on the track and mentioned it. We dismissed it too easily probably because the other observations on our tour had been so affirming. There was already a downtrack right through our slab - we hadn't noticed it until after the slide, but it's more reinforcement that tracks don't make a slope safe.

Overall, it ended up just being scary, but def took us by surprise. Stay safe and mind your spidey sense! You'll see the crown if you do this tour soon - it's looker's left and above the easier pass that returns to Early Winters creek, the one that is N/NW of "Copper Col".

Link to full NWAC observation with more detail and photo: https://www.nwac.us/observations/pk/4235/
Wow, that is spooky.  From your description and picture, I know the exact spot.  Even with its gentle convexity and shallow spots there, I'm sure I wouldn't have seen that one coming in the conditions.  Did you dig a profile to look at the new/old interface there?  Glad you two are ok - thanks a ton for the info!
2019-04-23 09:31:39
peteyboy
Thanks for the report, link, and photo!

Looks to be sun softened wind slab. Usually remains cohesive in the early hours retaining structure from overnight freeze (hence previous skier tracks), but then looses that structure and becomes volatile with softening by the sun and/or air temps.
Like you said most likely formed from the mid week snowfall (and wind) we had recently.

In your photo there are several visual cues of wind drifted snow formations... but I get it, I've been in similar situations, it's easy to equate Spring/Summer with stability. From experience I have learned there is no safe time of year... always good to keep an eye on weather a week prior to skiing wherever you ski.

Glad it was just a lost pole!
2019-04-23 11:07:02
cumulus
author=cumulus link=topic=41851.msg164831#msg164831 date=1555948670]
Thanks for the report, link, and photo!

Looks to be sun softened wind slab. Usually remains cohesive in the early hours retaining structure from overnight freeze (hence previous skier tracks), but then looses that structure and becomes volatile with softening by the sun and/or air temps.
Like you said most likely formed from the mid week snowfall (and wind) we had recently.

In your photo there are several visual cues of wind drifted snow formations... but I get it, I've been in similar situations, it's easy to equate Spring/Summer with stability. From experience I have learned there is no safe time of year... always good to keep an eye on weather a week prior to skiing wherever you ski.

Glad it was just a lost pole!


We thought this as well in retrospect. Thanks.
2019-04-24 11:49:39
Onward.
Had an extremely similar experience on Red Mountain, also yesterday. No red flags of wet and/or slab activity other than old debris and we remote triggered a wet slab up top. Totally caught us by surprise.

In retrospect we were ascending slopes that had already slid wall to wall earlier this week, which made for easy skinning and great stability. We didn't really consider the possibility of hitting slopes that had not slid, and definitely didn't consider the type of slab activity we triggered. Definitely a good lesson about being patient and waiting for robust freeze-thaw to stabilize the snowpack.
2019-04-24 15:37:47
Ross Bretherton

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Onward.
2019-04-21 21:16:40