Central/Northern Sierra Nevada, January 2017 Avalanche Cycles

[NakedShorts]

Just going to say Adrenelated and Schralph are on to the biggest area of concern when considering terrain selection. All three of the CAIC reports as well as the current incidents have shown when the problem has such high consequences and the magnitude can be larger than expectations the reality of ones choices can be devestating.

This AM when we drove past the skiers heading up WH/ PH it was raining at 830. Every skier had a hurried sense about them. Again it was raining. (I knew it would be also raining on me at the resort before my day began)

Is the point to go in the BC with this mental breakdown or to be relaxed?

You will find me in the resort most often and my church is the mountains. I enjoy the peacefulness of the BC. It is odd to me though to go into the wilderness and put myself in harms way with the largest rain event in a decade scheduled for the entire day and next day followed by snow and cold for the next week. If something bad happened it would be worse than normal. We all make choices, I skied and got some fun turns and real wet. I saw my entire front yard collapse while snow blowing this week. I have had my life saved from burial. I just wanted to share the emotions I noticed this AM was more Race than Pace. The mood at the resort was surprisingly light considering we were all dripping wet.

[rod9301]

A few comments:

1a) Adrenalated makes some hugely important points...The Mammoth Mountain results from the past few days clearly indicate that hitting the sweet spot on a slope with less force (order(s) of magnitude less?) can generate catastrophic results that military weapons (40 lb warhead) could not produce. I believe that the skier versus bombing argument will only lead to incorrect assessments, particularly in scenarios where deep failure propagation across a large area is at the peak of concern.

1b) In AIARE III, we spent a good bit of time probing the alpine to look for shallow regions across larger hazard areas that could serve as examples of these sensitive failure locations that would act to allow failure (collapse) and propagation of the failure across the slope. There are many, and these are what you don't want to find yourself!

2) The current avalanche cycle (and the Mt Rose avalanche incident/cycle) have many characteristics highlighted during large widespread avalanche cycles in the western US discussed in a paper that is currently in revision for the Journal of Hydrometeorology. I presented preliminary results at the International Atmospheric Rivers conference this August. The presentation can be found here. Summary: Early storms followed by dry, cold weather and low solar insolation and subsequent significant precipitation/loading (often due to ARs) are a grand recipe for massive avalanche cycles.

3) The Upside Down V (aka Fireplug) is one of the most non-textbook classic paths in the Rose region and such results are completely unsurprising. Good on the people for reporting their story, but the amount of mistakes they made are quite shocking. Very lucky outcome for a variety of obvious reasons.

What mistakes did they make?

[SchralphMacchio]

Updated original post to include Fireplug party's account, Jakes natural slide + SAC images from various events (just figured out how to get links to SAC images).

[wyeaster]

yikes

[SchralphMacchio]

you see that SAC observation of the natural that ran on Wednesday during the storm on Jake's?

I did and that gives me concerns ... If an area that is not wind protected slides ... It should be noted though that there were several red flags about the terrain that slid at Jakes. It was at the top exposed to wind, it was 38 degrees and facing North East. This is pretty much ideal avalanche terrain.

Hercule, I think you were looking at a different Ob. Look at this one:
http://www.sierraavalanchecenter.org...hes-jakes-peak


I've skied this line several times. The crown from the slide is well below treeline by about 700'. It's reasonably wind protected (except under huge prevailing winds or East winds), 35 degrees - looks like some "go to" terrain for a lot of people. It's right above some rocky gullies. I'd say that a 5' crown in this terrain, in most cases, would be unsurvivable if you were below it - airbag or not.

Let's talk about signs of instability on a tour before coming up to an area just like the one in the video. Here's a pic looking at the bed of the Jakes slide. This terrain looks relatively innocent, right? (other than the younger, smaller trees, hmmm)

The track is even scarier, as it looks JUST like a lot of Powderhouse.


If I were looking for a surface problem like slough, storm slab or windslab, on a tour up to this place, I might have signs of instability or contributing red flags like cracking snow, blowing snow, rippled texture, fast moving snow coming off turns ... I might have undercut the skintrack and dug a hasty pit to give quick results, maybe even an ECT ... so before I got to this wider steeper area I'd know enough to cause me to tiptoe a bit, and choose whether to enter it based on how reactive everything was feeling/looking and depth of the problem.

If we had whoomphing on the up or down, I'd hope that most of us would just really watch our asses and flat out avoid anywhere it's wide or steep enough to make fast turns, like in this pic.

What if I don't have whoomphing? As strength improves and the weak layer adjusts to the snow load, whoomphing becomes less common. It may very well be that the first "sign of instability" for a PS or DPS problem might be a slab popping out, just like the one in the video above. This is not an understatement! 3 years ago I dropped a freaking cornice on a PS slab, and then watched my buddy get killed as he skied 50 feet to the left of where we dropped it and ripped out the entire face on his 2nd turn. In March 2013 at Vail a slope with a DPS problem was skied 40 times before it ripped and killed someone. Sheep Creek April 2013 is an extreme example, but the first whoomph the party heard was the one that triggered the avalanche that killed half of their group.

That's the issue we have the longer in time after new loading has stopped and naturals + whoomphs start to go away. Also, successful skiing without incident is not the same as the problem not existing on those slopes. These persistent slab and deep persistent slab problems are not very obvious, but guess what, they are in the avy bulletin and Obs. The information about where the problem likely exists and how big it is, is right there, it's in the avy bulletin, it's in the pit data, and it has been known for weeks.

Brian Lazar (a rock star) has a great article about Sheep Creek and DPS cycles here:
http://www.americanavalancheassociat...14.pdf#page=15

With the complex snowpack we have ...

Let's go back to KISS.

Do we have a complex snowpack? Maybe complex, unusual for this area for sure.
Is integrating a lot of data about what's going on in the snow complicated? Sure, there's a lot to look at, a lot of possible tests and data, things are changing by the day, hour and minute.
Are there a lot of factors that might weigh into decisions and group dynamics? Of course.

But the strategy should be really simple:
If you have uncertainty about whether or not you can manage the avalanche problem(s), you need to make sure you are standing and skiing in a place where you are willing to handle the consequences of being wrong!

That's what terrain choice is all about.

I will also tell you, that if you're going to pick a fight with a guy at the bar, maybe it's not so wise to depend on good will or disposition to "bridge things over" before you poke a guy in the eye with a pool cue, a guy who is big enough to kill you with just one punch. Maybe you want to wrestle with a skinny yoke like me instead. That's how I try to look at avalanche problems - size and consequences first (but no I'm not always perfect, and that's a part of managing terrain and uncertainty as well).

I was wondering what your thoughts are the dangers of riding Powderhouse in avalanche conditions like these. I know that wind slabs can form in the open areas there but do you think that a deep slab could run through trees? What about in the more open areas?

Everyone is free to make their own choices about acceptable consequences, risk, terrain, etc. There's also a lot of microterrain management that goes into managing exposure on any part of any given mountain. Everything is very situational, and the "I wasn't there" factor definitely applies when weighing in on what other people are doing. Sometimes I'm not quite as neutral with my comments, especially when I think there's even a slim chance someone could get themselves killed.

I think the pics and examples I just posted above will answer the questions I've quoted above, and give you enough info to think about your own choices.

[TahoeJ]

What mistakes did they make?

Here's my amateur take: they allowed one positive pit and some snow punching to override the known slab / persistent problems on faces that steep, on a day rated as considerable. My personal outlook is for a pit to re-inforce what I'm already looking for based on the advisory and not change my opinion (unless it's for the worse). Snowpacks are not uniform so a single pit has a decent probability of being an outlier. This is why there's an entire thread on this forum questioning the usefulness of pits as an assessment tool. I don't necessarily agree with that but I understand the sentiment.

[NakedShorts]

The fun fact is DPS avalanches only account for 5% of incidents yet account for 42% of fatalities.

What ever happened to being satisfied with risk appropriate terrain choices? Living to ski another day, not starting an avalanche, and not getting caught. I doubt anybodies group yesterday followed a procedure that would have enabled self rescue. DPS avalanches are a different problem than the more common ones. The ENTIRE slope drops. Risk is mitigated not eliminated. Remote trigger is possible so a most cautious approach is advised and avoiding steep open / exposed faces is a no brainier...From the guy with no real formal training on the subject.

[MagnificentUnicorn]

What ever happened to being satisfied with risk appropriate terrain choices?

That's not core bro, gotta "get the goods", needs to be "steep and deep" or it's not worth it.

[SchralphMacchio]

Jay forget about the Considerable rating for a second. If you take it one level higher, to my simple strategy discussion above:

-The decision to ski a steep face with a known DPS avalanche problem that big is the equivalent of deciding to poke a Cave Troll (the big kind with the mace from LOTR movie) in the eye with a stick while he's taking a nap.

All the rest of the stuff - pit tests, travel techniques, etc. is akin to measuring his pulse, only keeping one person in the room at a time during the fight, etc. All that other stuff might give you a better sense of the odds or minimize the consequences but it doesn't change the beast you're messing with.

[LightRanger]

Just got around to reading the Fireplug account from the victim's fiance.

1. Glad they wrote it up.
2. Damn lucky.
3. Alex, I totally agree with your separate comments re radios.

[TahoeJ]

Jay forget about the Considerable rating for a second. If you take it one level higher, to my simple strategy discussion above:

-The decision to ski a steep face with a known DPS avalanche problem that big is the equivalent of deciding to poke a Cave Troll (the big kind with the mace from LOTR movie) in the eye with a stick while he's taking a nap.

All the rest of the stuff - pit tests, travel techniques, etc. is akin to measuring his pulse, only keeping one person in the room at a time during the fight, etc. All that other stuff might give you a better sense of the odds or minimize the consequences but it doesn't change the beast you're messing with.

Yes... the "considerable" rating was merely the cherry on top of everything else IMO. I'm curious though if you agree with my general take on pits - will you ever ski something more aggressive than you set out to that morning based on pit results?

[MagnificentUnicorn]

will you ever ski something more aggressive than you set out to that morning based on pit results?

I've always thought and learned that this would be bad form. Shouldn't a pit be used for informational purposes only and if something surprising is found lead you to back off your planned objective?

[TahoeJ]

I've always thought and learned that this would be bad form. Shouldn't a pit be used for informational purposes only and if something surprising is found lead you to back off your planned objective?

That's what I was saying further up. That was the mistake on fireplug - let the pit make the decision.

[hercule33]

Yes... the "considerable" rating was merely the cherry on top of everything else IMO. I'm curious though if you agree with my general take on pits - will you ever ski something more aggressive than you set out to that morning based on pit results?

I don't. I have gone to backcountry lodges in inner B.C. where guides have to manage tough avalanche conditions. If there is any change in the snowpack it is amazing how many pits they dig plus they share their results with other guides.

Also, keep in mind that this is terrain that they are usually skiing all year and have been skiing for years. This does mean they have to watch out for familiarity but they also have the advantage of knowing what terrain will have hidden trigger points and have set up safe skin tracks.

I will not claim to know their secret sauce but I will say I was guided by them in high avalanche conditions with PSLs to terrain I would never ski on my own.

Since I am not out on the snowpack daily and I sure as hell don't know the terrain (including micro terrain) like they do I wouldn't use a snowpit to give me a go in sketchy terrain. In fact, if I was in sketchy terrain, like Schralph said I would already consider that as a failure of decision making. The challenge of course is identifying what sketchy terrain is depending on the forecast which ironically doesn't involve digging pits.

[Unfrozen Caveman Lawyer]

But the strategy should be really simple:
If you have uncertainty about whether or not you can manage the avalanche problem(s), you need to make sure you are standing and skiing in a place where you are willing to handle the consequences of being wrong!

Alex - I entirely agree with your post above, but I particularly like this portion. With a DPS, the only way to mitigate/manage the avalanche problem is through careful terrain selection. Anything else is just window dressing, ultimately. With a DPS being such an atypical problem for the forecast region, many of the assumptions regarding terrain one makes (both on the macro and micro level) need a complete re-calibration. I though that SAC observations from Jake's was eye opening for the reasons you noted.

You are entirely correct to note that DPS also presents a significant risk of "false positives" as you travel through the terrain -> significantly much more than our typical avalanche problems (i.e., active wind slabs and storm slabs), which present themselves in a much more clear way.

I think the 2010 Saddle Peak Slide perfectly illustrates the "false positive" risks of DPSs. ISSW Paper: (https://www.mtavalanche.com/sites/de.../ISSW_2010.pdf)

[rod9301]

Here's my amateur take: they allowed one positive pit and some snow punching to override the known slab / persistent problems on faces that steep, on a day rated as considerable. My personal outlook is for a pit to re-inforce what I'm already looking for based on the advisory and not change my opinion (unless it's for the worse). Snowpacks are not uniform so a single pit has a decent probability of being an outlier. This is why there's an entire thread on this forum questioning the usefulness of pits as an assessment tool. I don't necessarily agree with that but I understand the sentiment.

Ok, I didn't know it was considerable on that day.

[teledad]

First black rose I've seen from SAC in many years:


Hopefully the conditions and advisory will keep people safe (i.e. out of avy terrain), and the rain will flush out the PWL/DPS one way or another.

[bodywhomper]

In tahoe, the sac forecasters have often observed deep weaknesses in the snow pack and have included them in their forecasts, but those weaknesses have not become active in the BC. That is tricky for the forecasters and those reading and using the forecast. My memory is that last season is the only long deep slab cycle that we've experienced in a long time.

There have also been some random spring incidents where those deep weaknesses have become active again in random but large spots; completely missed by any forecast.

[TahoeJ]

It may be 1-5 on the scale, but with this snowpack CRANK IT UP TO 6! #spinaltap

[LightRanger]

In tahoe, the sac forecasters have often observed deep weaknesses in the snow pack and have included them in their forecasts, but those weaknesses have not become active in the BC. That is tricky for the forecasters and those reading and using the forecast. My memory is that last season is the only long deep slab cycle that we've experienced in a long time.

There have also been some random spring incidents where those deep weaknesses have become active again in random but large spots; completely missed by any forecast.

Bell ringing in the back of my head...

Y'all remember that death on Tallac a few years back? I think he was gimpy and Joe's buddy? I seem to recap that being a deep-ish weak layer? Or maybe I'm remembering the forecasters moved the rating down to low and he got slid on a relatively mellow, familiar slope?

Your post jogged my memory about something being atypical about that incident.

[SchralphMacchio]

I think you're talking about Chris Trethaway, Treth's chute on Maggie's. March 2009 I think. Near crust facets but not as deep as what we have now, last year or Feb 2012. Forecast worsened with no new snow due to NCF formation I think.

[LightRanger]

That's it. Thanks.

[SchralphMacchio]

Feb 2009, for the record. SAC archives don't go back that far.
http://www.avalanche.org/data.php?date=&sort=&id=453

[LightRanger]

I recall that they had put it back to low danger on the advisory by that morning and some people were grousing about it...

[bodywhomper]

It sounds like some things may have hit the fan yesterday and last night.

If I remember right from feb 21, 2009 (I know you can look up the archived advisories), it was "moderate" that day because that persistent layer became active again the previous day. The reports back then came out later in the morning than they do now. The prior day was "low" and that layer was described as requiring a very large weight to be activated, more than the weight of a person or snowmachine. My own personal experience that day was a morning tour, no SAC forecast for up when I left home, digging a hand pit and finding the crust a few feet down, getting repeated q1 failures when I cut the back of my columns, carefully backing off my slope, and going home. Bcrider and j Jones were riding that same day off ralston area (I remember the Picts) and did not find concern with the crust in their area.