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Apr 03 2013

Technique: Meanderthal avy assessment

Ooops. Mount Judah’s east bowl wasn’t
as stable as last visit.

On a recent local lazyboy tour I hopped Sugar Bowl’s Judah chair for a fast slingshot into the backcountry. The summit chair wasn’t open, but that was fine, it’s only a 20 minute skin to the top and if you set the line right you can experience snow conditions from the northwest all the way around to the south without ever making a single switchback.

My preference is to throw a few in. Makes for a quicker climb to the microwave towers while confirming the best, and/or avy prone conditions by throwing in a few jackknife turns in select zones. Plus I like to include a little technique test for those who are switchback challenged and can’t do the free-pivot switchback dance (yet). It requires a little ballroom footwork, but less energy once you figure it out.

Slacker tour #1
Last time I did a slackcountry tour of Mt. Judah it was 24 hours after the storm, one week earlier. The riders in the storm had the best pow, or so I thought. A quick set of herringbone steps along the ridge brought me to the edge of a cornice. There was the usual debris at the top of the bowl, blasted down with dynamite by Sugar Bowl’s ski patrol to keep the cornice from building. It fell a quarter of the way down, no more. That indicated to me that heavy chunks had not, and probably still would not trigger a bigger slab. I’m betting most folks saw the debris as evidence of an avalanche. Indeed it was, but that was a has been condition. At the time I interpreted it as a sign of stability to have withstood a few explosions and the dynamic load of blocks tumbling down it weighing much more than this lone skier.

So I dropped in and enjoyed an untracked bowl to myself at 11:30am on a powder day, 100 feet from the boundary. Was that dumb luck or shrewd calculation? It didn’t matter, the evidence was on my side so I skinned up and did it again only in the hidden bowl to skiers right. Naturally, the track up was a meander fest.

Another unexpected result while meandering around the contours of a mountain – shooting cracks in a wind loaded zone. Shooting cracks in a wind loaded zone isn’t a surprise, but recognizing that this particular aspect (NNE) had wind loading was, thus influencing options for the rest of the tour.

Slacker tour #2
Today the summit chair was not running so I meanderskinned through the hemlocks wearing moss coats on the north side of Mt. Judah. The surface was a thick crust that was breakable, but not consistently. Underneath was a solid six inches of cold smoke.

Breakable crust didn’t sound all that promising for a ski down. On the northeast the crust was thicker and the cold layer beneath was denser, theoretically allowing me to stay on the surface. In hindsight, probably the best skiing. Certainly the most consistent.

Near the top of the ridge I zagged left under a small buttress of conglomerate and contoured around onto the southeast face being bombarded with energy. The crust was warmer and easier to break, but the layer beneath was still cold. It didn’t feel bad, in fact, it was tempting me to drop down, beckoning with a consistent pitch and squeezable softness through the trunks standing firm below.

Further out on the ridge I could see the effect of ski patrol’s bombing exercises. Unlike my last time in these parts, the cornice chunks did not stop part way down, but clearly triggered a flow of snow that ran to the bottom. The danger was clear: a denser, heavier layer on a weak, sugary layer below. Get a big enough chunk of the top layer moving and it won’t stop – transforming from crustacean to avy lizard once it gains momentum.

“Perhaps another day,” I mused, then continued on, hoping the north facing edge of this bowl would have soft, less crusted, less slabby snow.

Unrelated photo except as an illustration of a meanderthal trail along the west shore of Lake Tahoe that includes sampling multiple aspects – sensory and visual.

Along the way to my usual spot I decided to take a peak from the edge. In a spot I was vaguely confident wasn’t hung over I skirted near the line between snow and space to see where I might scout out a more secure spot that was only sheer, not overhanging. I spotted a wind gully 40 meters ahead that led to the precipice, with a steep flat ramp leading down to the bowl. As I pushed off, away from the edge, I heard a low crack, and in my peripheral, not more than a meter away, saw a 30 foot wide chunk of the cornice calve off and disappear.

I froze a moment, stepped hard on that same foot to see if it might go again, then tip-toed to the edge when it didn’t. Car sized chunks quickly broke down to basketball and refrigerator sized blocks and triggered the snow below to move en masse down the slope, rolling and tumbling over buried rocks and through the trees, never rushing until its momentum was overcome at the bottom.

Breakable crust was suddenly sounding a whole lot better.

The Lesson
On the way back to the north side of Judah I ran into a group with ASI doing their Avy Level 1 course. Since the guide was Tim Dobbins, a friend, I swung by to point out the activity just triggered. In the conversation I asked what the Sierra Avalanche Center had forecast for avy danger.

“Considerable on east and southeast faces,” Tim said, exactly as experienced. On the few times I’ve checked it this year SAC’s forecasts have been pretty spot on, including a moderate forecast immediately after the previous storm, again, spot on. Bravo for them in not falling prey to bureaucratic safety paranoia.

The meander path is a longer path —
definitely less traveled. ;)

Then one of the students asked why I didn’t check it myself. I must admit, I don’t check it much. Never have. I do more so when I’m in visitor mode, but not as a local. I prefer to rely more on field observations, and making a low angle skin track is an intrinsic part of that strategy. It isn’t fool proof, but it lets me see and ski through many more aspects than I ever would, or used to, on a steep neanderthal skin track.

Many’s the time I have changed my intended destination while meandering up a mountain because the snow conditions revealed themselves to be different than expected. Sometimes the change is obvious, like today. Sometimes I just feel a spookiness in the pack, like the day I went solo and there were two avy fatalities in-bounds in Tahoe. It isn’t completely physical, but there is always some sort of tangible evidence, but not always something I can articulate or completely understand, it just feels wrong. I like to think I’ve learned to notice those things, but in the end may be proven to just have been lucky for a long time without knowing it.

© 2013
 

  • Dostie

    As I said in my very last words on this post, maybe I’ve “been lucky for a long time without knowing it.” The Wasatch backcountry community lost one of their forecasters yesterday. The report (http://utahavalanchecenter.org/avalanches/accident-kessler-slabs) is sobering to say the least and reveals the Achilles heel of the benefit of covering a lot of aspects to suss out avalanche conditions. In the course of meandering on many different aspects it is possible to wander on to a slope, in a position that is merely intended to help you determine the danger but simultaneously puts you in the center of it. So be careful. And a heavy dose of condolences to friends and family, especially the wife and daughter of Craig Patterson