Yosemite Avalanche Information / Backpacking to Tuolumne Meadows in Late March

[wbolden]

What are the best places to get information on avalanche danger within the park?

I know about ESAC, but it seems like the area they forecast for is largely outside/east of the park. How much will forecasts given here apply to avalanche terrain closer to Yosemite Valley?

I also know about the Tuolumne Winter Ranger posts, and they seem to refer to ESAC often, so I assume ESAC forecasts are applicable at least some distance in to the park.

Specifically, I'm interested in backpacking to Tuolumne meadows, then through Cathedral Pass to Clouds Rest and back down to the valley. I have an outline of such a route here, though the actual route will of course be different than the trail-based one Google generates. This trip would happen near the end of March.

My concern is that near some places like Olmsted Point, Tenaya Lake, and Catheral Pass (among others), it seems like avalanche danger could be substantial. Does anyone have experience backpacking to TM in winter? Are there any generally-recommended routes to take to mitigate avalanche risk?

[paul]

ESAC is the best you can do. To my knowledge there is no avy forecast for the west slope of the Sierra, only the east.
I can't say I'm an expert, but I do pay attention to this as I take week-long backcountry ski tours sometimes. One thing I know from hearing about nearly every spring is that Olmsted Point is notorious for spring slides in which the entire snowpack slides off the dome and down over the road. The risk of this seems to play a part every year in the plowing schedule for the Tioga road. Due mostly to the smooth granite slabs at the appropriate angle. Easy enough to avoid going there. I'd be staying away from the road around Tenaya Lake as well, it runs right at the foot of some stuff that might slide - although most of that is to steep to accumulate any snow that could slide. But that brings up a general issue for the area, which is the steep slabs that exist in many areas, such that you have to be very aware in selecting a route that you avoid being at the foot of stuff that might slide. Of course that pplies anywhere, but it's worse wehen there are smotth underlying slabs. Your general attitude should be all about terrain avoidance, sticking to terrain that is inherently safe. If you already have the knowledge to do that, great. If you don't, there are some good books out there that can teach you a lot. They won't teach you to assess snow conditions and snowpack stability, but if you stick to the proper terrain then snowpack stability is not an issue.
I personally would be extra careful this year, because of the huge February we've had.

[bobby49]

I've never backpacked along there. In March 1980 a bunch of us did some of this on cross country skis. We started from Yosemite Valley and went to the Snow Creek Cabin the first day. On the second day, we got up to the Tioga Road and then headed east. There is a well-known slide area just east of Olmsted Point, so we went through there one at a time with 150-yard intervals. Then there are some other slide areas as you get closer to Tuolumne Meadows. I don't remember Cathedral Pass as being risky.

[wbolden]

Thank you for your replies.

Easy enough to avoid going there.

What do you mean by avoid exactly? Like stick closer to the hills on the other side of snow creek trail? I don't see an obvious way to avoid being beneath a slope (just looking at google maps images here, I'm not sure what it looks like there in winter).

I'd be staying away from the road around Tenaya Lake as well

How did you avoid the road there? Via the trail on the other side? Or is the lake frozen enough to walk on?

If you don't, there are some good books out there that can teach you a lot.

What do you recommend?

[bobby49]

How did you avoid the road there? Via the trail on the other side? Or is the lake frozen enough to walk on?

If you are good, you can navigate by the old original Tioga Road (the Great Sierra Wagon Road), or by the new Tioga Road (Hwy 120). When I was there in March 1980, Tenaya Lake was pretty thoroughly frozen over when we went east. Then when we were coming west a few days later it was starting to thaw around the edges. When you see liquid water on your ski tails, you know it is time to get out of there. Note that walking on a snow-covered lake is more risky that skiing across it.

[wbolden]

Is old Tioga this road here? Do you think a route up that road to May lake trailhead, then down to Tenaya lake to camp would be a good route to avoid Olmsted? Would you recommend a route along Murphy Creek to bypass the other slopes near Tenaya Lake?

[bobby49]

OK, on that old 1980 trip, we came up from Yosemite Valley on the Snow Creek Switchback Trail to the cabin, then we continued up to the highway. We followed the unplowed highway east, crossed Tenaya Lake, and then eventually reached Tuolumne Meadows. On the return back to the start, we took some detours. We found a restroom building at Tenaya Lake that was unlocked and heard sounds. We investigated and found a teenager collapsed on the floor. We fed him some hot drinks, and he started to recover. He was trying to walk from Lee Vining to Yosemite Valley, and the only food he had consisted of two big boxes of breakfast cereal. He refused all other aid, and he got up and left, postholing westward. Just west of Tenaya Lake, the remnants of the Great Sierra Wagon Road start from the highway and go uphill to May Lake HSC. Following that, we came down past the May Lake trailhead to the Snow Flat Snow Surveyors Cabin. Then we continued downhill to the highway. We crossed the highway going southwest and made it down to the Snow Creek cabin again. Then back down the switchbacks to Yosemite Valley. I don't know for sure why our leaders took us that way, but it would not surprise me if it was to avoid the Olmsted Point avalanche path on the return.

[paul]

I will be brutally frank, as I consider this a critical safety issue. I would be very uncomfortable suggesting anything close to a particular route for travel in the SIerra in Late March. If you have the necessary skills and knowledge and experience to make this trip, you can safely pick the route yourself. If you can't safely pick the route yourself, you should not be out there. I would be doing you a disservice to act otherwise. The dangers are real.

As to books: I can give you the names of four that I own:
"Snow Sense: A Guide to Evaluating Snow Avalanche Hazard" by Jill Fredston and Doug Fesler
"Secrets of the Snow: Visual Clues to Avalanche and Ski Conditions" by Edward R. LaChapelle
"Backcountry Avalanche Awareness" by Bruce Jamieson
"The Avalanche Handbook" by David McClung and Peter Schaefer

Also, see this post here on HST:
viewtopic.php?f=5&t=3640

[wbolden]

Thank you for the references.

I appreciate the sentiment, and I absolutely acknowledge the danger (else I would not have made this post), but I disagree with the conclusion that it is a disservice to offer route advice. It's like trying to teach an abstinence only sex-ed course. People are going to do it anyways, and their problems are going to be worse than if they'd been given more pragmatic advice.

I have some more general questions if you (or others) are willing to answer them:

How would I know whether or not I can safely pick the route myself? And why wouldn't I ask others to offer feedback on my route even if I was experienced?

What sources would a more experienced individual use to plan a route, and alternatives? As far as I can tell my main options are looking at slope angles online (which isn't going to tell the whole story given the limited resolution of most sources), and asking others about their experiences on similar routes. You can refine this route based on forecasts and observations once your trip begins of course, but I'm not sure there is anything else you can do in the planning phase.

[bobby49]

"How would I know whether or not I can safely pick the route myself?"

Based on your previous winter experience in Yosemite, you might know what previous leaders were thinking when they avoided certain areas. If you saw what they avoided and it made sense, then that is good. If you saw what they avoided and it did not make good sense, then more experience is needed. If you have general avalanche training, then that is helpful. If you have no previous winter experience in Yosemite, then that pretty much answers the question. How many others in your party are avalanche trained?