Avalanche forecast

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Sawtooth Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Relatively small avalanches are possible in wind-affected terrain—look for evidence of wind such as drifts, stiffened surfaces, or cornices. Triggering a very large avalanche on deeper weak layers is unlikely, but doing so would almost certainly be catastrophic. The safest conditions can be found on wind-sheltered slopes.

Avalanche problems

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2.5–3.5

    Weak, faceted snow from October exists near the base of the snowpack on most mid to upper elevation slopes facing NW-N-NE-E. Significant storms in December built a dense 3-5' thick slab on top of this weak layer, and it has become increasingly difficult for our weight to affect the weak layer. On wind-sheltered slopes where the snowpack is more uniform, triggering an avalanche is unlikely. 

    But—there's always a but—in wind-exposed, upper elevation, and alpine areas, the picture is less rosy. These places have two strikes against them. First: the wind over the past several days has continued to add more load to the buried weak layers. And second:  in this sort of terrain, shallow spots where you could impact the weak layer are more common. Triggering a deep persistent slab would almost certainly be catastrophic

    So why risk it? Safer conditions—and the best powder—can be found on wind-sheltered slopes. In these areas, the weak October snow has had more time to adjust, and you can also avoid wind slabs (Problem #2). Best to let sleeping dogs lie and take our powder hounding elsewhere!

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    W to NW winds have been moving significant quantities of our light, dry snow since last Thursday. Cold, NW winds (like the past few days) are often inconsistent/erratic and tend to be directed by the terrain, and loading patterns may change from drainage to drainage.

    Observers across the forecast area reported sensitive wind drifts yesterday, and a handful of small to medium-sized natural wind slab avalanches occurred. The wind eased overnight, but many of these wind slabs will remain reactive to your weight today. Wind-affected areas can be identified by pillowed drifts or dunes, cornices along ridge crests or running down subridges, and/or stiffened snow surfaces.

    These wind slab avalanches are likely to be on the smaller side, but if you find yourself in wind-loaded terrain, you're also in an area where you're more likely to trigger a deep persistent slab avalanche (Problem #1 above). Steep slopes where these problems overlap are where you're most likely to get into trouble.

    (1/1/2022) Wind transport observed on New Year's morning.

Avalanche Discussion

All MODERATE Danger Is Not Created Equal

When the danger drops from CONSIDERABLE to MODERATE, it's almost cliche for forecasters to offer an admonition about how conditions are still dangerous. Years ago, forecasters even coined a term for this situation—"scary MODERATE". Not surprisingly, that phrase didn't make it into the official Avalanche Danger Scale. There are two main reasons we get nervous about decreasing the danger rating. First, dropping the danger after an extended period of elevated hazard feels like opening the floodgates. Second, while the likelihood of triggering an avalanche decreases along a curve, the danger scale is stepped. Even though the danger rating has dropped a whole level from yesterday, conditions have changed only slightly.

So now that I have your sympathy for what a tough job we have, let me offer the words of caution. All MODERATE danger (or any danger rating for that matter) is not equal. That's why we have Avalanche Problems—to offer more nuance to conditions that may be oversimplified by the danger rating. A MODERATE rating with a Persistent (or Deep Persistent) Slab problem is almost always more dangerous than with other problems. Buried persistent weak layers add an element of complexity and unpredictability to snowpack assessment, and the avalanches they produce tend to be larger and more destructive. I would choose a MODERATE danger with some other (i.e. non-persistent) problem 95 times out of 100. 

So why are we dropping the danger? Even with persistent weak layers, the stability does improve slowly over time.  With our current conditions, the places where you could trigger an avalanche have become more isolated. But it's definitely not a free-for-all; if you go looking for trouble, you're likely to find it. If you avoid very steep, wind-affected slopes—especially those at upper elevations—you can dramatically reduce your chances of triggering an avalanche. 

Be sure to catch up on the week's conditions in Scott's latest Weekend Update.

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