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10/20/17, 12:31 PM

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Author Topic: March 19, 2017, cross post from NWAC obs  (Read 9960 times)
rlsg
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Re: March 19, 2017, cross post from NWAC obs
« Reply #25 on: 03/23/17, 06:03 PM »

This time of year, for low elevation skiing in particular, I would be more reluctant to ski south facing slopes that are wind slabbed up than N ones..  Wouldn't they be more susceptible to instability due to more heating?
ditto persistent deep pack issues that could be stepped down to...
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rlsg
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Re: March 19, 2017, cross post from NWAC obs
« Reply #26 on: 03/23/17, 06:39 PM »

I've seen ski tracks that started from a traverse onto a slope and below a short distance of cornice and have observed from the dropping of the cornice, pillow/slab immediately under the cornice, propagate resulting in the whole slope going.  So glad   nobody was below in harms way.  That is a very common place from my experience, to find instability when everything else is "blower"..  Not sure what  a pit or compression test/ext column  test would tell me about this very localized sleeper of a phenomenon -- that more times than I care to ever know, that are lurking above people, who are primed for their freshies just below.  {wind transport/eddying affect or effect-- seems to form immediately under cornices}
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slacker
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Re: March 19, 2017, cross post from NWAC obs
« Reply #27 on: 03/25/17, 10:39 AM »

TAY !  Thanks for a great discussion. It's been a pretty fantastic  snow year. The last week of February and the first two weeks of March especially so with stable cold weather conditions and fresh snow almost every night. 

In the North Columbia and Cariboo the Avy situation became much more of a concern around the fifth or sixth of March as all of the new snow stressed a buried rain crust.  Avalanche.ca reported at that time that the snowpack had reached a "threshold" .   This was not welcome news as I was just leaving for a week long hut trip in the interior. 

That trip, as it turns out it was completely epic. The snow was thigh deep and well consolidated.  The snowpack sloughed is places as we skied but we did not trigger anything that ran large or long, or stepped down,  or made us question our decision to be out. 

On Sunday the 12th ( the last day of our tour) it warmed up above zero essentially ending a season that was all about the steep and deep.

Since then the mountains have become a disaster zone. On a recent trip back from Alberta a friend of mine told me that the mountains in glacier and the Monashees have all slid. Carnage was the word he used. There has been a lot of slide  activity in the Whistler Corridor is well. NWAC is reporting similar conditions n the cascades.  Nobody I know is doing any riding right now.

I'm not sure but maybe the season is over for me. The words that avalanche.ca are using to describe the current snowpack situation are "historic and unprecedented"

All of this beta from avy.ca, nwac, tay and observations from the field have given me reason to pause and while I was tempted to go poke  around at Mount Baker this morning  I made the decision to stay home, drink coffee, and read trip reports. To me the reward  just isn't worth the risk at this time of year under these conditions.   





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rlsg
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Re: March 19, 2017, cross post from NWAC obs
« Reply #28 on: 03/25/17, 05:40 PM »

copy that!
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freeski
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Re: March 19, 2017, cross post from NWAC obs
« Reply #29 on: 04/02/17, 12:12 PM »

For those that know the skiing history of ruby mt i ask-

Would it have been a common occurance to have had 3 seperate groups stacked up in the avalanche terrain there before tay trip reports sent people out hunting for skin tracks in areas previously off the radar?

I seem to remember a thread where lowell and another chap argued the point of what i'd call  the 'tay trip report effect' concerning that very area.

I'm more interested in the human factors that influence a person's or group's risk tolerance then trying to speculate on how much energy is required to trigger an early artic air influenced  snow pack.

Because as Gary states, that is unknowable.

That unknowable energy equation is the reason why i got concerned when a guide and his friend followed TN,Nick and myself up the hwy 20 Big Kangaroo Gulley last winter.(High consequence area, a place where you do not want to have another group of avy triggers above you).   

[ It is also the reason why we don't park our machines in the avalanche path run out zones along hwy 20 and why we minimize time spent in avy terrain. And why we practice individual seperation within a group to avoid multiple burials and to place less stress on the snowpack].

Many poacher Groups don't seem to think twice these days about transferring  their risk onto the group ahead of them.

yea, i know, we're not comfortable talking about human factors.   

Large avalaches are nothing new.Most of our open ski lines that form below tree  line exist because of them. 

What is new is that an ever increasing number of people are exposing themselves to that risk. 
« Last Edit: 04/02/17, 12:23 PM by freeski » Logged

"I'm not making love to anyones wishes, only for that light I see." Cat Stevens
freeski
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Re: March 19, 2017, cross post from NWAC obs
« Reply #30 on: 04/02/17, 03:06 PM »

Ron, with deep instabilities be they surface hoar, facets, or bond to ice crusts (or even a wet layer or graupel for awhile), if buried deeply, even recognizing the weak layer and testing it doesn't help all that much unless and until the results become nearly uniform across terrain. For one, even if you get such and such marginal test result, if it is deep, there is no way to evaluate whether or not it could be triggered in any particular location. Just how does your body influence the layer through the overlying snowpack? Could a cornice trigger it? Could a small snow slide trigger it? Exactly how much strength does the overlying snowpack impart to the ability of the snowpack to resist failure? What are the rather nebulous abilities of some particular structure to transmit energy?

And then, too, how does the structure of the snowpack change with location? And what location? What elevation? What aspect? How do the kinds of dynamics in meteorology that Klassen pointed out affect the snowpack here, or there, now or then?

A good place to see the results of a whole bunch of snow profiles is to go to Avalanche.ca, select Glacier National Park, and go to the bottom of the page and choose Snow Profiles. There is a large catalog of profiles. Pick two different ones on or about the same date and see how they vary. Note the 3/17 profile which looks suspect for stability, and then look at the one preceding it in which only a short profile was done because the structure was obviously so good. Choose profiles for the same location on succeeding dates to see how the snowpack at that location changed with time.

Simply, in graphical form the blue represents the hardness of different layers, the little symbols the type of grains, the test results are on the right.


Btw.Excellent Post Gary. One or a few questions if i may.

Would it be safe to say that those folks standing on that Ruby cornice combined with other recent loads (energy input), even further if down the ridge, may have provided the tipping point for the energy requiried to trigger that cornice?

That based upon snow slabs (fracture propagation) being sensitive to rapid new energy loading as a trigger. 

On march 31st, it was reported to me that at least one skier was travelling along a cornice ridge near Hinkhouse peak (above wa. Pass) and a nearby cornice collapsed which triggered a 30m wide  avy that ran 300m.

I wish i had more information as to aspect, i assume those gullies above near the overlook parking area. And running in recent surface snow, which only supported by recent observation that area and reported as a d2.

 
 
« Last Edit: 04/02/17, 06:53 PM by freeski » Logged

"I'm not making love to anyones wishes, only for that light I see." Cat Stevens
Lowell_Skoog
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Re: March 19, 2017, cross post from NWAC obs
« Reply #31 on: 04/03/17, 05:33 PM »

Would it be safe to say that those folks standing on that Ruby cornice combined with other recent loads (energy input), even further if down the ridge, may have provided the tipping point for the energy requiried to trigger that cornice?  

I don't think it would be safe to say that.

No one was standing on the cornice when it fell. The skiers on the ridge were at some distance from the cornice at the time it toppled. It's not clear to me whether anyone had skied near the cornice during the day. (I wasn't there, but I know party members who were.)

If there was any skier contribution to the cornice failure, it was separated from the actual event by both time and space.  My conclusion is that it was just the wrong day to be up there, but I don't think anyone could have predicted what happened.
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freeski
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Re: March 19, 2017, cross post from NWAC obs
« Reply #32 on: 04/05/17, 09:11 AM »

I don't think it would be safe to say that.

No one was standing on the cornice when it fell. The skiers on the ridge were at some distance from the cornice at the time it toppled. It's not clear to me whether anyone had skied near the cornice during the day. (I wasn't there, but I know party members who were.)

If there was any skier contribution to the cornice failure, it was separated from the actual event by both time and space.  My conclusion is that it was just the wrong day to be up there, but I don't think anyone could have predicted what happened.


Thanks for the reponse lowell. Having never been to the top of Ruby, i wasn't sure how the terrain lays out and  if the cornice extends down to where those skiers topped out and therefore connected.

You are correct, by definition deep persistent slab avalanches are had to predict for any particular slope.

Skiers skinning, skiing and re-skining on such a slab would certainly add strain energy to such a slab, although without a direct trigger at that time it would be hard to know if it was a contributing factor for the slabs later release.

So can we rule out skier snowpack stress as a contributing strain factor?

I only make that point to state how we add energy stress to a snow pack. 

So DSP avys are hard to predict, however, large cornice drops had become more likely due to our recent warm temps, rain, and snow loading.

So i wouldn't say it was the wrong day to be there, i would say that IT IS  the wrong time in general to be under a cornice given the recent weather that favors large cornice failure (although chunks can and do fall all the time).

I was in the Blue Peak area on march 19th, and as i reported on another tay thread,  (which i later removed because of thread drift) we observed that the center section of a very large blue peak cornice had failed, with two car sized chuncks.

The cornice failure resulted in triggering  an avalanche  on the steep slope below the cornice that extended to the rock wall-snow slope interface of blue peak with a 12'' or so crown line.

The cornice and avy sent debris over the bench area (heli lz and common skin peel area), and over the next steep  roll with another section going down  spire gulley. Lots of killer sized large chunks.

There was new snow on the debris and that cornice was observed to be intact on the 16th and was observed by another group on the 17th to have fallen.       

I don't know if that group on that 17th passed that information on to nwac. If so, it would have helped spead awarness (like the excellent ruby observation), if not, a lost oppertunity for awareness, imo.
« Last Edit: 04/05/17, 09:55 AM by freeski » Logged

"I'm not making love to anyones wishes, only for that light I see." Cat Stevens
alecapone
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Re: March 19, 2017, cross post from NWAC obs
« Reply #33 on: 04/06/17, 09:27 AM »

For those that know the skiing history of ruby mt i ask-

Would it have been a common occurance to have had 3 seperate groups stacked up in the avalanche terrain there before tay trip reports sent people out hunting for skin tracks in areas previously off the radar?



I think the Tay effect has respectfully been replaced by the Volken effect.

My experiments have revealed the Tay effect wears off once a trip date becomes stale. They have a shelf life of about 2 weeks to a month. Or far less if your trace gets erased.

Volkens book is the opposite. People sit on their toilets reading it daily, scheming...Waiting for that window.

Very casual observation is that you are more likely to find people on routes out of Martin volkens new guide book. Ruby would be one. I've noticed a few others. The recent parking situation at Arrowhead/Jim hill could probably be due to increased interest as well. People out doing the routes has increased, while reporting is half what it was.

Doesn't bother me, I think it's a good thing. If I want to see someone, I go to one of the tours I know are in his book. If not, I go somewhere else.  Also think people are more likely/better off following the description from a trusted/trained guide then some random kook on the internet. Less likely to deviate from the tour the have been pining over, and follow/poach a random skin track.





I don't own it, only flipped through, but you can preview it online.

I have a winter climbing in Scotland guide book on my toilet.



« Last Edit: 04/06/17, 09:36 AM by alecapone » Logged

scott
freeski
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Re: March 19, 2017, cross post from NWAC obs
« Reply #34 on: 04/07/17, 09:19 AM »

I think the Tay effect has respectfully been replaced by the Volken effect.

My experiments have revealed the Tay effect wears off once a trip date becomes stale. They have a shelf life of about 2 weeks to a month. Or far less if your trace gets erased.

Volkens book is the opposite. People sit on their toilets reading it daily, scheming...Waiting for that window.

Very casual observation is that you are more likely to find people on routes out of Martin volkens new guide book. Ruby would be one. I've noticed a few others. The recent parking situation at Arrowhead/Jim hill could probably be due to increased interest as well. People out doing the routes has increased, while reporting is half what it was.

Doesn't bother me, I think it's a good thing. If I want to see someone, I go to one of the tours I know are in his book. If not, I go somewhere else.  Also think people are more likely/better off following the description from a trusted/trained guide then some random kook on the internet. Less likely to deviate from the tour the have been pining over, and follow/poach a random skin track.





I don't own it, only flipped through, but you can preview it online.

I have a winter climbing in Scotland guide book on my toilet.






I knew ruby had that tay trip report conflict going on from the lowell-amar heated debate several year ago, but i didn't know ruby had been commercially 'guide booked' (i only read that books forward section).

Guide books certainly tell people where to go, but not when it's safe to do so.

And you're right about tay trip reporters. I don't read them because it's frustrating reading the unsafe mountain techniques that are on display there.

Like one that i read where the solo trip reporter followed another solo guy  up a steep narrow coulour.

Many will think that's ok.

However, imo, the first rule of any human mountain activity should be-

Don't put others at greater risk of harm because of your actions, without their prior consent.   

learn that lesson in the mountians and practice it in daily life.

« Last Edit: 04/08/17, 07:44 AM by freeski » Logged

"I'm not making love to anyones wishes, only for that light I see." Cat Stevens
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