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Avalanche terrain travel

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Re: Avalanche terrain travel

Postby taylorzs » Sat Apr 27, 2013 5:45 pm

apasquel wrote:I have very limited experience on slopes...but what I see on TRs and what I have learned seem to contradict. Everything I "know" says that while traveling on slopes with potential avy danger, you want to travel one person at at a time until reach safety zone...however, every mt. Shasta report I see climbers climbing side by side or on this site you the same thing on different 14ers...which got me thinking, many of the reports I've read in the last few years have many experienced, very competent backcountry travelers on this site traveling next to a partner in their TR. my assumption is...there are times when you can travel slopes together? I don't know...but I do know this, I am climbing sneffels next week and I would love your input on how to approach the lower slop and lav col with a partner. Can anyone give me a number on how steep the slopes are? With the next week weather forecast (really nice but warm trend), what should I be most concern with? I would imagine time and getting off the slopes before it gets too warm...


Yeah, all that is a bit contradictory huh? A couple thoughts here. ANYTIME it is remotely possible to travel on avalanche terrain one at a time I do. Even in a strong spring melt freeze cycle (which we are not in yet, atleast not in the northern/central Colorado mountains).
That is standard avalanche protocol, taught in any avalanche class on the planet. However, it is not generally reasonable to travel one at a time up a 3000 foot long snow couloir either. Standard backcountry practices of exposing one person at a time to avalanche hazard simply do not work in this type of situation. So yeah, pretty much anytime I am climbing up a snow couloir, unless I am by myself, I am generally climbing right next to several friends, and we are all exposed to the same avalanche hazard. In a very real sense, we take on a greater risk in this situation. This increased risk can be tempered by only doing this when the snow pack on the route has seen a strong consolidation cycle driven by daily melt freeze cycles for an extended period. We monitor the snow the whole way up and turn around if it starts to get water saturated. To the experienced eye, typical spring snow conditions (not this year!) are much more predictable and a lot can be told just by climbing on the surface of the snow(which is not true in a winter type snow pack, you have to dig).
I personally am comfortable with climbing straight up a snow couloir with friends next to me, under very specific, certain condtions. I feel that I have the skills, experience, and knowledge to evaluate the snow and take responsibility for my decision to go up a couloir with friends or not. In light of recent accidents, many of the deceased had similar experience levels and competancies to my own and probably felt the same way. You have to learn a lot about snow and recognize that a bad judgement call can mean your life, and your friends. This is a very serious responsibility to take on.
On the plus side with experience, avalanche classes, and mentorship under more experienced avalanche travelors, it is my opinion that these types of travel practices CAN be done safely, as safe as driving your car down the interstate anyway. Accidents happen though! If you chose to travel on avalanche terrain, avalanches can happen, no matter how careful you are, but if you are well trained, experienced, and cautious, you can bring that hazard down to what I would consider an acceptable level, for myself anyway.
I do not know your skill level and am not competanet at evaluating your own abilities and knowledge. These are just my thoughts about my travel experiences/decision making practices in avalanche terrain, coming from a dude on an internet forum so take them with a grain of salt.
I have climbed and snowboarded the Lavender Col. It is an avalanche path that is plenty steep to slide (probably 35-42 degrees). Getting off the snow early before it gets soft will be important. The couloir is south facing is I remember correctly so it gets early sunhit too. There are a lot of factors that go into understanding whether that slope is safe or not and I cannot tell you all about that on an internet forum. It is too complex and something learned over years of travel. A little advice though, if you do go; I would absolutely want to be back down at the base of the couloir, done with the climb, by 10am at the latest. I would not go if overnight lows are close to freezing or warmer. You need a solid overnight freeze. I believe the San Juans are a bit more stable over all (relatively speaking) to the rest of the state right now but there could still be lurking deep slab instablities too that could go at any time too. This is common in the northern/ central mountains right now. If you hear whumping or see cracking or recent avalanche actrivity in the area turn around.
Those maps that show pitch angle are good for initial planning but they are no substitute for evaluating terrain when you are actually there. They give you a very broad, macro view of terrain pitches. Small slopes that slide (and are plenty big to kill you) do not always show up on a map like that. It is a tool, but only one of many to be used in combination to travel safely in the mountains on snow.
Good luck if you do go and be safe! Zach
"May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view. May your mountains rise into and above the clouds." Edward Abbey
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Re: Avalanche terrain travel

Postby WSN » Sat Apr 27, 2013 7:36 pm

taylorzs wrote:
apasquel wrote:I have very limited experience on slopes...but what I see on TRs and what I have learned seem to contradict. Everything I "know" says that while traveling on slopes with potential avy danger, you want to travel one person at at a time until reach safety zone...however, every mt. Shasta report I see climbers climbing side by side or on this site you the same thing on different 14ers...which got me thinking, many of the reports I've read in the last few years have many experienced, very competent backcountry travelers on this site traveling next to a partner in their TR. my assumption is...there are times when you can travel slopes together? I don't know...but I do know this, I am climbing sneffels next week and I would love your input on how to approach the lower slop and lav col with a partner. Can anyone give me a number on how steep the slopes are? With the next week weather forecast (really nice but warm trend), what should I be most concern with? I would imagine time and getting off the slopes before it gets too warm...


Yeah, all that is a bit contradictory huh? A couple thoughts here. ANYTIME it is remotely possible to travel on avalanche terrain one at a time I do. Even in a strong spring melt freeze cycle (which we are not in yet, atleast not in the northern/central Colorado mountains).
That is standard avalanche protocol, taught in any avalanche class on the planet. However, it is not generally reasonable to travel one at a time up a 3000 foot long snow couloir either. Standard backcountry practices of exposing one person at a time to avalanche hazard simply do not work in this type of situation. So yeah, pretty much anytime I am climbing up a snow couloir, unless I am by myself, I am generally climbing right next to several friends, and we are all exposed to the same avalanche hazard. In a very real sense, we take on a greater risk in this situation. This increased risk can be tempered by only doing this when the snow pack on the route has seen a strong consolidation cycle driven by daily melt freeze cycles for an extended period. We monitor the snow the whole way up and turn around if it starts to get water saturated. To the experienced eye, typical spring snow conditions (not this year!) are much more predictable and a lot can be told just by climbing on the surface of the snow(which is not true in a winter type snow pack, you have to dig).
I personally am comfortable with climbing straight up a snow couloir with friends next to me, under very specific, certain condtions. I feel that I have the skills, experience, and knowledge to evaluate the snow and take responsibility for my decision to go up a couloir with friends or not. In light of recent accidents, many of the deceased had similar experience levels and competancies to my own and probably felt the same way. You have to learn a lot about snow and recognize that a bad judgement call can mean your life, and your friends. This is a very serious responsibility to take on.
On the plus side with experience, avalanche classes, and mentorship under more experienced avalanche travelors, it is my opinion that these types of travel practices CAN be done safely, as safe as driving your car down the interstate anyway. Accidents happen though! If you chose to travel on avalanche terrain, avalanches can happen, no matter how careful you are, but if you are well trained, experienced, and cautious, you can bring that hazard down to what I would consider an acceptable level, for myself anyway.
I do not know your skill level and am not competanet at evaluating your own abilities and knowledge. These are just my thoughts about my travel experiences/decision making practices in avalanche terrain, coming from a dude on an internet forum so take them with a grain of salt.
I have climbed and snowboarded the Lavender Col. It is an avalanche path that is plenty steep to slide (probably 35-42 degrees). Getting off the snow early before it gets soft will be important. The couloir is south facing is I remember correctly so it gets early sunhit too. There are a lot of factors that go into understanding whether that slope is safe or not and I cannot tell you all about that on an internet forum. It is too complex and something learned over years of travel. A little advice though, if you do go; I would absolutely want to be back down at the base of the couloir, done with the climb, by 10am at the latest. I would not go if overnight lows are close to freezing or warmer. You need a solid overnight freeze. I believe the San Juans are a bit more stable over all (relatively speaking) to the rest of the state right now but there could still be lurking deep slab instablities too that could go at any time too. This is common in the northern/ central mountains right now. If you hear whumping or see cracking or recent avalanche actrivity in the area turn around.
Those maps that show pitch angle are good for initial planning but they are no substitute for evaluating terrain when you are actually there. They give you a very broad, macro view of terrain pitches. Small slopes that slide (and are plenty big to kill you) do not always show up on a map like that. It is a tool, but only one of many to be used in combination to travel safely in the mountains on snow.
Good luck if you do go and be safe! Zach


Lots of good information.
I am curious, how do you think about "if overnight lows are close to freezing or warmer". I think in May, at around 12000 ft, the low temperature forecast (noaa.gov) for a day will likely to be higher 20's (say, 29). Do you consider this "close to freezing"? If so, then the couloirs in May are generally unsafe? Or this kind of forecast is generally inaccurate?

Re: Avalanche terrain travel

Postby taylorzs » Sat Apr 27, 2013 7:54 pm

WSN wrote:
Lots of good information.
I am curious, how do you think about "if overnight lows are close to freezing or warmer". I think in May, at around 12000 ft, the low temperature forecast (noaa.gov) for a day will likely to be higher 20's (say, 29). Do you consider this "close to freezing"? If so, then the couloirs in May are generally unsafe? Or this kind of forecast is generally inaccurate?


Glad you appreciated the information WSN. That is a good question, I was purposefully vague because it was one of many points I wanted to make in a fairly long post and explaining that specifically takes a little writing. Happy to answer though since you asked. It is good infomormation to understand. Basically, this is how it works;
Cold air is denser than warm air, so when there is no wind, cold air tends to pool in the valleys, displacing warmer air to higher elevations. When this happens (called a temperature inversion) the high summits and mountain faces are often warmer than an overnight low forecast for 29 at 11,000' (typical NOAA forecast). So while the forecast may say 29, it may actually have never gotten below 33 or 34 at a higher elevation. Other nights, with a breeze where air is moving around, circulating more, and does not settle you could have an overnight low temperature of 29 at 11,000' and it will be even colder as you go higher in elevation. So then the snow pack is bomber, if we are in a typical spring freeze-thaw pattern (not currently true yet this year). This is fairly complex to evaluate because an overnight low temperature according to a weather forecast is not an absolute to rely on (it is a useful tool to incorporate with many others though) and experienced climbers often get caught off guard by this because things do not always get cooler as you ascend in elevation. It is also important to understand that forecasts from NOAA and other weather agencies are a nice tool but are often innaccurate in presenting this type of information. A lot of computer generated weather models do not incorporate topographical influences to weather, precipitation, and temperature variation at different elevations. That is why I often like to sleep at the TH before a climb to get a sense of winds and all the factors that come into play in this type of understanding before I commit to an avalanche slope. This is also why mountain weather forecasts are often inaacurate.
Hope that makes sense.
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Re: Avalanche terrain travel

Postby mattyj » Sat Apr 27, 2013 11:17 pm

Thanks shaunster, the pictures help a lot. And sorry apasquel for the ongoing thread drift. As far as snow v. ground, in general the elevation measurements should be based on summer conditions, but I really have no idea how much effort is put into catching near-permanent snow features when they're snow free.

When you said the shading was "off by several hundred feet", I thought you meant that it was actually offset that far from where it should be, which really concerned me. It looks like you just meant that there were 30+ degree measurements at least several hundred feet from any shaded areas, which is a different issue and one I feel much better about. There's no minimum size / percentage needed before I shade an area, but it's certainly possible for smaller features in the low 30s to slip under the radar due to topo/DEM inaccuracies - that's why I shade down to 27, although it's clearly not always enough.

My contour lines match the topo almost exactly, so I think the shading issues are due to survey errors from the original map. For the area you flagged 30-32, I measure 200' between the contour above and the contour below, which gives a slope angle of 21 degrees. This is exactly what my shading scripts computed from the DEM (right-click, measure, point info). The left 29-31 marker is effectively the same angle, but the spacing between contour lines is drastically different than at your 30-32 measurement - producing a whopping 11 degrees. That's an obvious sign the topo has issues.

In this case I feel like the shading is as accurate as the topo, and no more misleading that what you would get from making measurements off the map. It's clearly not good enough, but I also don't think it's indicative of a rendering flaw or some other issue with what happens after I get the data. I may ask borrow your images at some point though - they're a good example of the tool's limitations.

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Re: Avalanche terrain travel

Postby apasquel » Sun Apr 28, 2013 5:53 am

Zach...thanks for all that,and thanks for taking time to share that. That's good stuff...this weather stuff is a whole lot of science!!!! Who what thunk!!! :-k

Re: Avalanche terrain travel

Postby Bean » Sun Apr 28, 2013 5:59 am

taylorzs wrote:So while the forecast may say 29, it may actually have never gotten below 33 or 34 at a higher elevation.

And if the skies are clear and winds are calm, this may still result in a rock-solid freeze of the snowpack thanks to radiant cooling.

This stuff all comes with time and experience in the hills...get some education, and make conservative choices while you learn. It'll come.
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Re: Avalanche terrain travel

Postby taylorzs » Sun Apr 28, 2013 7:48 am

Bean wrote:And if the skies are clear and winds are calm, this may still result in a rock-solid freeze of the snowpack thanks to radiant cooling

That is sometimes true as well, as you know there are a lot of factors to take into account in the snowy mountains.

Bean wrote:This stuff all comes with time and experience in the hills...get some education, and make conservative choices while you learn. It'll come

Very good advice Bean!

apasquel wrote:Zach...thanks for all that,and thanks for taking time to share that. That's good stuff...this weather stuff is a whole lot of science!!!! Who what thunk!!!

You are welcome. Have fun on your snow climbs and be safe!
"May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view. May your mountains rise into and above the clouds." Edward Abbey
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