It slid last week so it's good…right?

Hoping to start a knowledgeable discussion about decision making regarding the safety of a slope that has knowingly avalanched during a recent storm cycle on top of a resilient crust. Here's our recent representative scenario: New snow on an old crust. Cold temps throughout. Known poor bond; as storm total is building, the new snow is gaining cohesion. Avalanche rating risk is high, all kinds of signs of the layer being highly reactive. Shooting cracks in the trees, tons of whoomphing, even large remote triggers. The whole tree of red lights. We skied (on the very knowledgeable advice of the owner guide of the area we return to every year) a zone where he had ski cut and slid each vulnerable shot earlier in the storm cycle. But now 40 to 80 or more cm on top of that in less than a week. Skied every shot with no signs of instability whatsoever.
For our decision making, I wonder about slide activity on a mature crust: how well and for how long/much new snow at what speed/wind/temps can we trust that we won't just have a shallower cohesive new slab on the same poor bond? Really an issue for when there is rapid reloading like we just had. I realize that buried surface hoar crystals will be wiped out by avalanching the slope, but the crust remains. Not looking for mathematical answers, just to generate thought and comment.

Anecdotally, I have had experiences in the Crystal BC where it was areas that had recently slid that were more prone to releasing their most-recent slabs than were areas very nearby that had not slid. Could see slightly buried debris piles beneath such slides as clues. Hypothesis is the smooth scour of the previous slide had made the underside of that slab even less likely to bond to the base, and more able to obey gravity's call when it was separated or tweaked by a ski cut. On the plus side chances are lesser that it would step down to next layer beneath scour. Maybe, subjective on how much "new" slab there is, as to whether a slid slope is safer, or not?

A slide can create a slick bed surface for subsequent snow falls. This is likely why some tracks are frequent performers.

I think that you have to be wary with this... avalanching can (and often does) hit the reset switch, but if a slide occurs on a crust and the next snow event does not bond well to the crust, you are back where you started.

Here is a short discussion from The Avalanche Review. It references a continental snowpack, but the points are valid here as well - there is no silver bullet.

www.avalanche.org/moonstone/Forecasting/...Snowpack.TAR28.4.pdf

Ten four that frsg...

That's why I feel we got lucky. But I posted this because I have found this to be a fairly pervasive opinion point of slope safety - much like "it gets skied a lot".

It's clear from inbounds ski area operations that sufficient avalanche control work is capable of rendering normally avalanche prone slopes safe-enough to sustain ski area operations even in deep storm conditions, so it's possible that your guide was correct. Making expert calls is the realm of experts; some will argue that there are no experts.

Caveat skier.

Below is a video of "Employee housing" going big yesterday at Crystal.    I saw large crowns and slides down to the old/bad layer in Niagras/O-Meadows nearby when this terrain opened a few weeks ago.  I didn't notice big crowns in EH.   Did EH slide down to that pre-storm layer, can't say.   Just wanted to point out that this is a slope regularly controlled by experts and people have been skiing it for weeks.  But conditions changed (ie. rain, warm), so yesterday control work produced different results.

Yea but they re-bomb those slopes or ski cut them after a new storm loading event prior to opening the area. Sometimes it slides, sometimes it doesn't. If they, the experts truely knew whether or not a slope was safe, why waste the cash and place even more toxic chemical explosive residue into the enviornment? I think that i have offered factual proof here on tay that some commerical guides, your experts coming out of ski area patrols, hide their client related avy incidents. This creates a false sense that the experts know what they are doing and does not further the goals of education or client safety.

Because no "Expert" is going to point at slope in the winter and say it's 100% safe

I've had "experts" tell me a slope was 100 % safe.  I skied it but that was because I thought it was "probably" "pretty" safe.  A few years later up there way north of the boarder at the same place, "experts" were guiding a bunch of folks and a bunch bit it...I assume they were marching fairly close just like on my trip.  No Way any  body knows when a slope is "absolutely" stable;  at best the calculation of somewhere near "low" risk is possible....everybody should be "calculating their own risk" and not leaving this to somebody else, IMHO...

The use of the word expert in this sport is over used

So much for the skier compaction theory ie...Hamburger Hill Chair 6 Crystal.
A few years back there was an eye opening picture of the Moguls under the Glacier chair at Blackcomb where the slope had given out to a similar type avalanche. That is an eye opener when hard pack moguls pull out like a slab avalanche!

So much for the skier compaction theory ie...Hamburger Hill Chair 6 Crystal.
A few years back there was an eye opening picture of the Moguls under the Glacier chair at Blackcomb where the slope had given out to a similar type avalanche. That is an eye opener when hard pack moguls pull out like a slab avalanche!

Such slides occur on a fairly frequent basis, nothing new here...

... read up and don't assume that snow gets better through the season.

Such slides occur on a fairly frequent basis, nothing new here...

... read up and don't assume that snow gets better through the season.

I don't see it very often on packed runs maybe you can provide more reading fodder.
Frequently maybe deeper into spring but we got much rain that it accelerated that progression of saturation. Kinda the perfect set up with the crap layer. Often times DOT comes across this in late April or May on their highway opening work.

Ha found it after some searching...
Great example of skier compacted area that pulled out at Blackcomb Heavenly Valley run lookers left of Glacier Basin Chair in May 2008.
It is more dramatic with the cat track and moguls in the picture...strikes home that it can happen even in the most compacted zone.

Many years ago I had seen some spring pull outs at Chinook Pass that were natural which had 3ft crowns and it really gave me an anything can happen feeling.

Lots of miss information floating around. Recent observations for our area,east NC were that no step down had occured during last cycle. I guess the climax avy that left a pile on hwy 20, cutthoat path doesn't count? Or how about the whole wall on Pica peak that lost it's entire snow load,except the hanging cornice. That mass of snow did not step down pica bowl,however.  Watch out for generalized statements based upon generalized observations for a generalized area.

I hate to continue the thread drift but I wanted to address something said by freeskiguy.  I agree that there has been a lot of misinformation floating around but I think we probably disagree on where it is coming from.  When you quote past avalanche forecasts you should be careful to look at when the forecast was put out.  You paraphrase a forecast that stated "no step down had occured [sic] during the last cycle".  That particular forecast was put out on Thursday March 6th, which was well before the last avalanche cycle that caused all of the avalanches you refer to.  I can understand an honest mistake but with your track record I felt obligated to correct your observation.   

For those of you that are wondering what happened with the most current avalanche cycle, I have been out the last three days (Sunday - Tuesday) traveling through a lot of the terrain around Washington Pass to observe these avalanches, including a day with one of the NWAC forecasters.  There was a large natural cycle on Saturday but we observed only three avalanches that were deeper than the recent storm snow.  One large avalanche that has run down to bare glacial ice multiple times this year (north aspect 8,400').  One relatively small pocket on a steep hanging slab on an east aspect near 7,800', and the third avalanche was on a solar aspect that was difficult to assess whether or not it was more than just storm snow.  Not to downplay these large avalanches but considering the weather event that caused them I would have expected more. 

The other avalanches freeskiguy refers to did not step down to the deeper (late Jan/early Feb) layers from what we observed.  They were large but that would be expected considering the amount of storm snow, warm temperatures and the type of terrain these avalanches came out of (very steep, rocky terrain).  Personally, I think NWAC did a good job of forecasting this avalanche cycle.  If you go back and look at the forecast for last weekend it was about as accurate as you could hope considering they have such a large area to forecast for and only one forecaster a day to accomplish that huge task.  I know I'm biased because I work as an observer for NWAC but to have someone imply that professional observers and NWAC forecasters are intentionally giving the public misinformation is very offensive.   

where did i say or imply that nwac was intentionally miss informing the public? Maybe that observation exists within your own bias. Lets deal with the facts like, i did not read that nwac report you say that i paraphased. It is also a matter of public record that the FS took permit action to enforce permitted terrain boundaries for two outfitters in our area. I was a part of that action as well as other safety related conflicts resolution. I stand by my ''track record''.  

I'm sorry about making assumptions about what you were referring to. What you wrote made it sound like the "miss information" was coming from professional observations made in the Washington Pass area. What information were you referring to?

where did i say or imply that nwac was intentionally miss informing the public? Maybe that observation exists within your own bias. Lets deal with the facts like, i did not read that nwac report you say that i paraphased. It is also a matter of public record that the FS took permit action to enforce permitted terrain boundaries for two outfitters in our area. I was a part of that action as well as other safety related conflicts resolution. I stand by my ''track record''.  

It is just that your track record is so often antagonistic. I am going to agree with you that organizations have made mistakes and even possibly overstepped boundaries intententionally. Members of the public have in the past and will continue in the future to make poor decisions.

If your true goal is education you might consider that at least one person stops hearing your message when it takes the tone of zealous evangelism.

if you  want to have a valid discussion on all relevant topics of bc safety and how some of the old time,local BC skiers communicate, i would welcome that. However, last time we tried that, it did not go well. My only option has been to seek regulatory intervention and control, which is the right of all citizens concerning public land use. 

If you cannot answer my question I'm going to have to assume that you were referring to the avalanche forecast.  If you have valid critiques of the forecast, or can offer more information about avalanche and snowpack observations that would be great.  The more eyes in the field the better.  I suggest you post your observations here. www.wwu.edu/huxley/spatial/maps/nwac/.  If you would like to improve the accuracy of your observations and your ability to communicate these observations I'd suggest taking an AIARE Level 2 avalanche course.  With your interest in the ski guiding profession this might be a good place to start to learn more about the professionalism required for entry level guides. 

Sometimes FSG and I agree, sometimes we don't.

No such thing as perfect accuracy when it comes to prediction and snows desire to slide down the hill. I appreciate NWAC and Jeff Wards efforts. Much better that anything we've had in the past.

Matt

Hopefully productive conversations, though that's officially one jacked thread.
Seriously, thanks for the insight from those who responded to the topic.
Looking forward to everyone's input about that now crazy deep crust when spring melting percolates down to it on our favorite late season routes.

Hopefully productive conversations, though that's officially one jacked thread.

What were you expecting my friend? A learned discussion focused on the topic? HaHa.

Avy forum+east side locals= thread jack and some seriously entertaining exchanges.

I enjoyed it all. Jeff Ward, fabulous work this winter. My hat is tipped to you and others at the new observer program at NWAC.

exactly. And to add. Jeff, thanks for your suggestion about the avy class. A old time guide friend once suggested that i take an avy three course. I remember him asking my advice on where to ski because he had not been out yet. I think he trusts my obsevations because i told about a wl i had seen and later the pwl that resulted in a slide that his clients dug him out of using ski tips because he had the only shovel. Any way, on the tour i advised him on, I informed him about those snow flake thing types that are very bad to have,especially near the ground. He had a problem free tour. Meanwhile, my friends on a different tour triggered a climax avy after skiing and skining back up the slope. They, however did not try to hide that mistake and we all learned from it, both in a practicle sense and an ethical sense. 

At times it can be difficult to understand what you are trying to say. In this particular post are you implying that guides are hiding avalanche incidents from the public? If so, I'd love for you to just come out at say it. NCMG reports all avalanches, natural or skier triggered, to NWAC every day we are out. This is not something that is required from the Forest Service. This is something we do as a public service so NWAC can provide a quality avalanche forecast for the area.

I am glad to hear that I wasn't the first person to encourage you to take an avalanche course. I thought it might be taken the wrong way coming from me. It doesn't appear that you have a good understanding of the effort and professionalism that is needed to accomplish a standard day of guiding. I think the more effort you put into this part of your education the more effective your comments/critiques of the guiding profession will be. If you truly want to make a change in what is going on you will probably need to put in a little more effort in this category.

One observation i had this year was seeing large guided groups skiing on the slopes below delancy ridge on 2-15 and 2-16 during all that loading. Those large D3s came down to the hwy with a little more loading what, less than 48 hours later? There is a reason you don't see the locals on those slopes during major loading events. Can we expect not to see the guides out under simular conditions in the future? Or maybe you don't consider this  to be a close call because your observations told you  exactly how much loading was reguired to bring this mass down?

Let me fill out some of the missing information here:

"A little more loading" is quite an understatement. Those avalanches came down in the early morning of the 19th after a ton of new snow, falling at a very high rate. Our groups on Delancy on the 15th and 16th had snowfall rates averaging S1 (1 cm per hour) during their time out there and the avalanches that eventually came down (approximately 72 hours later) did not come down the terrain they were using.

If you pick your terrain wisely, Delancy can be a reasonable place to ski during a storm cycle. Quite a few locals use Delancy as a storm skiing zone. I agree that there are times when it might be inappropriate but I disagree with you when you imply that having skiers there on the 15th and 16th was inappropriate.

As far as group size goes, we had two groups out on the 15th. Each group had 4 guests with 1 guide. On the 16th we also had two groups out. Each group had 3 guests with 1 guide. This information is an attempt to help define what you meant by large.

besides the nwac report there are three commercial outlets containing commercial bc reporting available in the methow valley. Don't assume what you don't know as fact.

Could you be a little more specific? I'm not sure what you mean by "three commercial outlets containing commercial bc reporting".

I could ask you again what misinformation you were referring to but I doubt we would get a straight answer. It doesn't really matter. What concerns me is that you implied that these large avalanches were running on the deep persistent layer. From what we observed, that wasn't the case. If you have more information regarding this it would be very helpful. I doubt many people are making decisions based on your comments but I'd hate to see someone think that those slopes are good to go because the deep persistent layer has been wiped out (trying to bring the thread back to the original subject - sorry once again about the major thread jack).

Jeff

This back and forth reminds me of a quote from Mark Twain - "Never argue with a fool, onlookers may not be able to tell the difference". I should have heeded Twain's advice before responding to your post, but I think it has been worth it.