Lawinenlagebericht

Salt Lake

Utah Avalanche Center
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Lawinengefahr

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze
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Veraltet — dieser Lagebericht ist 9 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Today, upper-elevation, steep slopes facing west through north and east have a CONSIDERABLE avalanche danger for triggering a slab avalanche on the Oct/Nov facets now buried 1–2 feet deep. Mid-elevation slopes with the same aspects, which received slightly less wind and snow, have a MODERATE avalanche danger.

Across all upper elevations, there is also MODERATE danger for wind-drifted snow, which has the potential to step down and trigger deeper avalanches.

Careful snowpack evaluation, cautious route-finding, and conservative decisions are essential today. Sunny skies and fresh powder are tempting, but most accidents happen after peak instability. Avalanche terrain can be avoided, and fun riding is still possible on lower-angled slopes.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2

    To get an avalanche, you need three things working together: a weak layer, a slab on top of it, and a slope steep enough to slide. Right now, we have all of that, with old October/November facets buried under recent storm snow on slopes steeper than 30 degrees across the northern half of the compass.

    We saw plenty of proof over the weekend, with widespread avalanche activity and obvious red flags. As we move farther from the loading event, those signs might not be as obvious, but the dangerous setup is still very much in play.

    This extends through both upper- and mid-elevation terrain, and both should be approached with caution, though upper-elevation slopes are the most suspect today. These areas received the most snow and have the most connected weak layer. Avalanches in this setup can even be triggered remotely, meaning you could collapse the weak layer and start a slide from a distance.

    Yesterday, I went to check the slide Trent and Brooke remotely triggered on 12/6. It broke roughly 1-2 feet deep, spanned nearly 200 feet, and was powerful enough to bury or injure someone. Check out my video BELOW.

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2

    The northwest winds have been cranking for several days now. In some areas, these winds have scoured the snow surface, but in others, they are actively drifting snow and forming fresh soft and hard slabs. Be on the lookout for slopes that are loading or have that rounded, pillow-like appearance. Cracking under your feet, a hollow feel, or stiff, chalky snow are all signs of fresh wind drifts you should avoid.

    These drifts can appear a few hundred feet below ridgelines, in protected terrain features or catches, or right around treelines. Even if the ridgeline looks scoured, the slopes just a few turns below can still be loaded with fresh, unstable pockets of wind-drifted snow. Keep an eye out for these spots, as they could be easy to trigger today.

    On slopes where a weak layer of faceted snow lies underneath, even a small wind drift can overload the structure. The added weight from the wind can make an avalanche break deeper and wider, increasing the likelihood of a human or remote trigger and making the consequences much more severe.

Recent Activity

The avalanche reports from the weekend slowed down a bit yesterday, but a few more trickled in from both mid-storm on 12/6 and post-storm on 12/7. Most of these slides failed on northerly aspects where the heavy new snow overloaded the buried Oct and Nov faceted weak layer. At some point during the storm, many slopes went through a natural avalanche cycle. Be sure to check all avalanche observations HERE.

Yesterday, one party remotely triggered a persistent slab avalanche in the Lake Desolation/Beartrap region about 50 yards away from their location and experienced multiple collapses throughout the day. The avalanche broke around 12 inches deep on facets on a northeast aspect near 9,400 feet. Exact dimensions are unclear.

Other parties continued to report cracking and collapsing.

Example of the natural cycle many slopes went through mid or post-storm. Natural persistent slab in the Birthday Chutes, NW aspect at 10,600 feet. Failed 2 feet deep and 100 feet wide on buried facets.

Snow and Weather

This morning, skies are mostly broken and temperatures range from the mid-20s to low 30s °F. Northwest winds continue at 10 to 20 mph, with gusts into the 30s across most upper elevation wind sites. The free air at 11,000 feet is a different story, with averages near 45 to 55 mph, with gusts pushing close to 60 mph.

Today, skies will be cloudy in the morning with the possibility of a few lingering flurries, then gradually clearing to sunshine in the afternoon. Winds will ease a bit, blowing from the west-northwest and averaging 10 to 20 mph, with gusts up to 25 mph across most upper elevation sites. The free air at 11,000 feet could continue to gust up to 55 mph. Mountain temperatures will climb into the low to mid-30s °F around 8,500 feet.

For the outlook, there is potential for generally light precipitation Tuesday into Wednesday, with less than 0.1 inches of water even at the 75th percentile. Snow levels will be high, rising above 8,500 feet by Wednesday.

General Announcements

This information does not apply to developed ski areas or highways where avalanche control is normally done. This forecast is from the U.S.D.A. Forest Service, which is solely responsible for its content. This forecast describes general avalanche conditions and local variations always occur.

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