April 2, 2006, Heather Ridge - Buried Weak Layer
4/2/06
WA Stevens Pass
2714
4
We had some really fun turns today, but found some sketchy conditions as well. A pit we dug on the NW face above Tye Lake failed before we could even do a test. There was about 6" of heavy settled powder on top of a 2" very firm crust (rain crust? looked like it). As soon as we separated the rear portion of the column the whole thing sheared off below the rain crust. Underneath the crust was a thin layer of very sugary faceted snow. The whole thing slid right off as soon as the column was isolated. This was on a 46 deg slope, NW facing. We turned back and found some safer skiing on the NE aspects.
Could we have broken through that firm crust? Seems all too likely. How far would that crust propagate a failure? The 6-8" of heavy snow on top would have made a big mess. We were expecting sluffing down to the crust, but not that weak layer underneath it. Any thoughts on what could have caused this layer?
I'd love to hear from some more experienced WA skiers on this one. I'm new to the northwest this season, coming from Colorado. The general rule of thumb I've heard is that new snow is the danger, while lurking weak layers are a rarity. Any general thoughts on spring skiing up here? Does the snowpack generally freeze up solid at night? Can S aspects be skied or is the danger of wet slides too high?
Could we have broken through that firm crust? Seems all too likely. How far would that crust propagate a failure? The 6-8" of heavy snow on top would have made a big mess. We were expecting sluffing down to the crust, but not that weak layer underneath it. Any thoughts on what could have caused this layer?
I'd love to hear from some more experienced WA skiers on this one. I'm new to the northwest this season, coming from Colorado. The general rule of thumb I've heard is that new snow is the danger, while lurking weak layers are a rarity. Any general thoughts on spring skiing up here? Does the snowpack generally freeze up solid at night? Can S aspects be skied or is the danger of wet slides too high?
Thanks for info Pat. I was thinking of visiting this slope tomorrow but will revise plans. We have had a lot of east winds in last few months. Tye Peak gets heavily loaded on SE aspect and is bare for a reason. That steep NW is often stable but the east winds can funnel through the Nason drainage. I have seen large amounts of debris on the NW slope over the years. All aspects of that hill require lots of respect. NWAC and this site have mentioned bad layers in isolated areas where close by it might be bombproof. You just found one. April can be quite deceptive before real consolidation occurs. If you see posts from Gary Brill or some of the really sharp folks here pay close attention.
Glad to help, Nick. I should clarify the location a bit. This is not the face that leads down into the Tye lake basin. It is the NW face off peak 5476 that leads down to the Nason creek drainage. The face above Tye lake had some tracks on it yesterday, but I can't say how old they were.
Well then, I think you mean the top of Skyline (sometimes called Heather) Ridge. That big bald hill to the west is generally called Tye Peak. My previous comments refer to that one. No real name to drainage separating the two. I call it south fork of Nason Creek.
There has definitly been a lot of active wind activity this winter, especially during February and March, resulting in crusts and loading.
We skiied the southern aspects of Skyline Ridge Saturday, finding some rotten and very unstable, but shallow, layers clearly as a result of the recent warm weather and probably rain. Much of it hadn't refrozen in the more recent cold weather.
We set off some slow wet slides in one area in particular, that has slid almost every time I've skiied there. A lot of debris too in the gullies coming down the south aspect of Skyline.
We skiied the southern aspects of Skyline Ridge Saturday, finding some rotten and very unstable, but shallow, layers clearly as a result of the recent warm weather and probably rain. Much of it hadn't refrozen in the more recent cold weather.
We set off some slow wet slides in one area in particular, that has slid almost every time I've skiied there. A lot of debris too in the gullies coming down the south aspect of Skyline.
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