Yosemite Avalanche Information / Backpacking to Tuolumne Meadows in Late March

Discussion about winter adventure sports in the Sierra Nevada mountains including but not limited to; winter backpacking and camping, mountaineering, downhill and cross-country skiing, snowboarding, snowshoeing, etc.
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bobby49
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Re: Yosemite Avalanche Information / Backpacking to Tuolumne Meadows in Late March

Post by bobby49 » Wed Mar 13, 2019 11:36 pm

Incidentally, the logistics for crossing Yosemite one-way are lousy. I've gone in from Lee Vining to Tuolumne Meadows, and I've gone from Yosemite Valley to Tuolumne Meadows. Trying to go from Lee Vining to Yosemite Valley is awkward unless you have some one-way air available.

Been there, done that.








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Re: Yosemite Avalanche Information / Backpacking to Tuolumne Meadows in Late March

Post by wbolden » Thu Mar 14, 2019 12:31 am

Just to be clear, I'm not suggesting I can pick out a safe route myself at the moment. I definitely think I need assistance in that area, among others.

My winter backpacking experience in Yosemite is limited to the Pohono trail/Glacier point area, where there is minimal avalanche risk. There is currently one other person in my party, and neither of us have taken an actual in-person avalanche training course. Obviously this is less experience than anyone on this forum would recommend.

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Re: Yosemite Avalanche Information / Backpacking to Tuolumne Meadows in Late March

Post by longri » Fri Mar 15, 2019 7:47 am

I did your route in March of 2011 except that I went counterclockwise and also didn't have time for Clouds Rest. It had dumped a week and half earlier and had snowed again the day before I started. So the notion of taking skis up out of Happy Isles seemed halfway reasonable. Despite the recent snows the spring like weather made conditions pretty easy for the most part. In fact I was disappointed how quickly areas at low elevation (e.g. Little Yosemite Valley) were already melting out. The snow depth then was roughly what you'll have, assuming we don't get a big dump in the next week or so.

I didn't sense any real avalanche danger on that trip. I don't recall Cathedral Pass as being any sort of a danger spot. It's pretty wide open there.

The two spots that come to mind with respect to avalanche risk are Olmstead Point and Pywiack Dome. If conditions are concerning you can avoid Olmstead, either going well below it or traversing above it via Snow Flat. I'm not sure how you'd skip Pywiak. One time during a snowstorm, just as I cleared the Pywiack/Polly gauntlet and skied out onto the relative safety of Tenaya Lake, I heard what sounded like a big release of snow just behind me. I suppose it could have been thunder. I'll never know which it was as I couldn't really see anything.

You'll probably be fine. But don't take my word for it. Who am I anyway? Just some guy on the internet.

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Re: Yosemite Avalanche Information / Backpacking to Tuolumne Meadows in Late March

Post by wbolden » Fri Mar 15, 2019 12:54 pm

I'd been thinking something like this for bypassing Pywiak/Polly, though it still looks like there are some slopes to be concerned about: https://i.imgur.com/JEAl8fY.jpg

The map is from caltopo, shaded by angle. Green is 20, yellow 28, red 40.

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Re: Yosemite Avalanche Information / Backpacking to Tuolumne Meadows in Late March

Post by Beantown » Tue Mar 19, 2019 1:06 pm

wbolden wrote:
Wed Mar 13, 2019 9:56 pm


How would I know whether or not I can safely pick the route myself?
Sounds like you need to take an avalanche class.

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Re: Yosemite Avalanche Information / Backpacking to Tuolumne Meadows in Late March

Post by paul » Wed Mar 20, 2019 1:25 pm

To elaborate on my earlier post and clarify: Yes, you do need someone to help you select a route if you are inexperienced; but you need more than that, you need to be able to adjust due to terrain features that are not clear from a topo map, and due to prevailing conditions. And there's no way I can convey all of the details that you should be taking into account. If it was matter of choosing a route that has no avalanche risk whatsoever, that's possible in certain situations - but I don't think the area you want to travel through qualifies. You'd need an area where none of the slopes you are going to be anywhere near are over 30 degrees. In that kind of terrain there is virtually no avalanche risk regardless of conditions. But when there are slopes steeper than that, either above where you want to be, or below where you want to be, or right where you want to be, then there is risk to one degree or another. If I were to say, this route is safe, and then you had to deviate from that route for some reason, you could be in trouble. That's why I wouldn't suggest a route and say it should be safe regardless of conditions. Avoiding avalanche terrain is not that hard, but it's rather like route finding when you are off trail in the summer- It's a question of being aware of a lot of little clues as well as the big ones.
The easy way to do it is to go later in the spring, after the snowpack is consolidated. Then all you have to deal with is the possibility of afternoon wet slides, and those are much easier to avoid. Late April/early May is the prime time. ESAC basically stops forecasting at some point when they consider the snowpack to be fully consolidated, usually around the end of April.

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Re: Yosemite Avalanche Information / Backpacking to Tuolumne Meadows in Late March

Post by Harlen » Thu Mar 21, 2019 11:05 pm

First, welcome to HST wbolden, and kudos to you for having the cojones to get out there in the snowy Sierra. Secondly, you are wise in your desire to gain knowledge, and sensible to ask questions.... but what the folks above are pointing out is the fact that safety on snow slopes during the snow season can present wicked problems. There are some unseen dangers that are very subtle- for instance check this out from my favorite text Staying Alive in Avalanche Terrain, by Bruce Tremper:

What is the Slope Connected To? "You don't have to be on a steep slope to trigger it-- very important. ... it's common to trigger steep slopes from and adjacent slope connected to it. We call these remote triggers."" The book then shows a drawing of a skier on flat ground beneath a slope, triggering the collapse of the above slope by by cutting the lower anchor point.

"... I have collapsed flat slopes that triggered avalanches on steep slopes up to a quarter mile away. I have lost a couple of friends who died doing this very thing. ... In extreme conditions, especially with thick hard slabs, victims have been pulled off flat ridges this way."

Paul and others just cannot with a clear conscience attempt to describe a safe route for you guys, knowing that conditions can change radically- for instance, by a new snowfall accompanied by a significant wind-loading event; or if unseasonable rainfall and heat occur. Please don't take offense, they are in large part covering their own compassionate arses. My own pet fear is breaking through frozen? lakes. I have skied across Tenaya Lake to avoid the avalanching slopes to the west, and on another trip to avoid deep snow drifts- but I was extremely cautious, and still fearful enough to hug the shoreline. So I know never to blithely advise someone to "avoid the avalanche slopes above the road west of the lake by skiing across the lake." What if you broke through?! Okay? I do think you are on the right track with some of your observations bolden, e.g., below when you are assessing Paul's point.

Part of Paul's comment was:
... Easy enough to avoid going there.
wbolden writes:
What do you mean by avoid exactly? Like stick closer to the hills on the other side of snow creek trail?
Correct if you mean avoiding the treacherous avie area just east of Olmstead Pt. by skiing well out into the heavily forested zone around the outlet of Tenaya Lake. I have continued all the way around to safe ground under the big paved parking area before returning to the roadway, and in scarier times, you might want to stay down there, well away from the road for a longer distance.

You're on the right track bolden; I can't recommend enough reading and rereading the chapters on "Terrain Management" in the texts noted in this post. All the best.

DSC01545.JPG
When it gets dicey, we send the youngest child out ahead.

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Always go last yourself. :nod:
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