Bollettino valanghe

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

To reduce the chance of triggering avalanches, avoid slopes where the wind recently formed drifts or slabs. In areas more protected from the wind, triggering a 2-3 foot thick avalanche is possible. An incoming stream of new snow will continue loading buried weak layers. Pay attention to the consequences of being caught on even smaller steep slopes or terrain with rocks, cliffs, and trees.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2.5

    This zone has persistent weak layers buried 2-3 feet deep on most middle and upper-elevation slopes. There's no magical formula, but the most important factor we have on our side is time. It's been two days since the snowpack has been significantly stressed by new snow, wind, or major temperature fluxes. Imagine how you'd feel after two days on the beach with no email, no texts, and no news: probably pretty good, but you'd want more time there. Having more time is good for both you and the snowpack—but this problem is still very much present. Avalanches are being reported daily on this interface and most of these show wide propagation across slopes and terrain features. More snowfall overnight tonight and into Thursday will test these layers. Persistent slab avalanches are unpredictable on the best of days. If you find one of the land mines out there—and believe me, they exist—the MODERATE danger rating will mean little to you. Given the uncertainty surrounding these weak layers, skiing or riding in "prime-time", consequential avalanche terrain mean accepting this unknown and the risk associated with it. 

    ADDITIONAL DISCUSSION

    The Wyoming Range continues to have a thin and tricky snowpack with layers of weak snow near the ground and mid-pack. Triggering an avalanche on the above layer could step down and trigger a very large avalanche deeper in the snowpack.

    With skies remaining overcast and little incoming precipitation today, avalanches on steep slopes at low elevations are less likely. If this storm produces enough moisture over the next 72 hours, rain and warm midday temperatures may start to peel snow off of these areas in the form of wet avalanches.

     

    (3/26/2023)

    Mosquito Creek Area remote triggered avalanche that failed on March 20th weak layer. 2-3' crown depth. D2 R3

    Photo: Will Mook

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    The wind has plenty of ammunition in the form of new snow available for transport to craft slabs. Expect to find some stiff or hard wind slabs in exposed terrain, and some of these may remain reactive and be buried beneath further snowfall over the next several days. Monday night's new snow and wind produced some natural avalanche activity, and stronger winds today could continue building slabs. Though not huge, these wind slabs could be sensitive to your weight and are stressing the buried weak layers described in Problem 1 above. The easiest way to avoid this hazard is to recognize this problem and avoid slopes steeper than 35 degrees. If you see cracks shooting out from your skis or sled or feel hollow, drum-like, or chalky snow, you've found a wind slab. 

    It is worth noting that continued snowfall into the spring will build cornices that may behave in unpredictable ways. Steer clear of being beneath or directly above these features; skin or sled on rocks, trees, and whatever clues you into the fact that you are anchored to the ground, and not floating on the back of one of these monsters. 

    (3/27/2023)

    Avalanche triggered from a low-angle ridgeline in adjoining steep terrain on a NE aspect around 10,000'.

Avalanche Discussion

In my earlier years, the question I often asked before committing to avalanche terrain was, "Do I think this is going to slide?" If I thought the answer was no, I went for it. This process felt pretty simple, especially in areas I skied frequently and felt I "knew." I knew the conditions under which X  or Y slope would avalanche. If those conditions weren't present, it made answering that question all the easier. But asking this question left such a small margin for error because whether or not a slope is going to slide is a tough one to accurately answer. I also answered this question wrong a few times.

Over many years, you see snow behave in a lot of strange ways that surprise you. I've realized that question isn't possible with an acceptable level of certainty. The other day, standing next to a steep slope at Togwotee with my partner, we asked a subtly different question, but that difference is important. "Would we be totally surprised if this thing avalanched?" This question is more conservative and takes into account the uncertainty faced when dealing with a tricky snowpack—which is what we have now.

So do I think someone will trigger a slide today? No. But would I be totally surprised if someone does? The answer is also No. As time has passed and my avalanche knowledge has increased, I've ridden less steep terrain—not more. When I do ride steep terrain, I enjoy it more knowing that I am more confident in my decision and that I'm exposing myself to less risk.

Regioni coperte