Bollettino valanghe

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

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Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
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In sintesi

We've observed numerous large and destructive natural avalanches since Tuesday. You are likely to trigger similar slides today—especially in steep, recently wind-drifted terrain. Avalanches may be triggered remotely—from below, above, and to the sides of steep slopes.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    This zone picked up around 1" of SWE since Tuesday afternoon. This load was enough to release large slab avalanches in the Boulder Mountains and cause a widespread avalanche cycle in the Smoky Mountains (observation, observation). Avalanches occurred on many different aspects, in both obviously wind-loaded and generally sheltered terrain. 

    A weak layer of sugary facets buried in mid-December is responsible for the vast majority of natural and human-triggered avalanches so far this season. If we've learned anything from previous storms, it's that this weak layer doesn't like to be poked and it can remain irritable for days following a storm. A spate of human-triggered avalanches followed each of our last two storms and we should expect human-triggered avalanches to be likely again today. 

    Remotely triggering slides from below, above, and to the sides of steep slopes is likely. Travel conservatively, particularly if you find stiff, freshly formed wind slabs near the surface.

    (1/13/2021) Numerous natural persistent slab avalanches in Anderson Creek in the Smoky Mountains.

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2

    Recent strong to extreme SW-W-NW wind rapidly built fresh wind slabs. Expect to find both hard and soft slabs in many locations. These slabs will be thicker and more widespread at upper elevation, but touchy wind slabs may exist in exposed terrain at any elevation.

    Hard slabs can be tricky to deal with. You may be able to travel some distance out onto a slope before finding the "sweet spot" where the slope fractures leaving you little chance to escape. Wind slab avalanches that release near ridgelines could "step down", failing on layers deeper in the snowpack and becoming much wider than the initial avalanche. 

    (1/14/2021) This small wind slab was intentionally triggered above the Baker Creek drainage on Thursday.

Avalanche Discussion

Tuesday and Wednesday's storm dropped anywhere from 0.5-1.5" of SWE. For storm totals across the forecast area, check here. Although precipitation diminished early in the day Wednesday, strong to extreme W and NW wind continued to load slopes at all elevations. Skiers reported continued strong wind yesterday, rapidly filling in skin tracks at middle and upper elevations.  To give you an idea, you can look at these photos from Wednesday and yesterday and watch a short clip of the active wind-loading here. 

The uncharacteristically weak nature of the facets in the lower third of the snowpack has produced widespread natural avalanche cycles with relatively light loads. This last storm, while not huge, again tipped the scales. Continued wind-loading following the storm has only added to the problem. Yesterday, I observed numerous avalanches in the Baker Creek drainage. Some appear to have run in the same location as avalanches that failed during the previous cycle on January 4th and 5th. Several dozen more were observed along the Smoky Crest and north into the Sawtooths. While by no means a complete list, you can check out the ever-growing tally of observed avalanches on our interactive Avalanche Occurrence map here. 

The lure of fresh snow and mild weather over the next few days will be strong. Trust me, I get that, but I urge you to build an extra safety margin into your travel plans. The weak layer we're dealing with is special, but I hesitate to call it "unpredictable". We've seen what it can do, and we know it can be touchy for days after a loading event. Don't lose sight of those facts as you choose where to ride this weekend.  

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