Avalanche forecast

Logan

Utah Avalanche Center
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Avalanche danger

  • Alpine
  • Treeline
  • Below treeline
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Dangerous avalanche conditions exist on drifted upper and mid elevation slopes across the Logan Zone and people are likely to trigger avalanches failing on a sugary persitent weak layer near the ground. With more new snow, the danger is higher in the northern part of the zone, and the avalanche danger is HIGH. Avalanches are most likely on drifted upper and mid elevation slopes facing northwest through southeast, and possible in sheltered and lower elevation terrain. Avalanches could be triggered remotely or from a distance.

Continue to avoid travel in avalanche terrain today. Stay off, away from, and well out from under all drifted slopes steeper than about 30 degrees.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    The buried persistent weak layer problem involving sugary faceted snow is a very dangerous and notoriously tricky avalanche problem, and it is responsible for most fatalities, injuries, and close calls in the Logan Zone.

    Sunday, I triggered subtle collapses and extensive cracking, and several 1'-deep frowns, 20 to 30' wide and 10 to 20' above me on a 25 degree slope on the backside of Beaver Mt., on an east facing mid-elevation slope. A developing and now more cohesive soft slab was failing on loose sugary faceted snow above a stout crust that was on the snow surface in November.

    Cracking like this is a red flag indicating unstable snow.

    I found these nice large faceted grains or depth hoar buried near the ground in Steep Hollow yesterday.

    • Avalanches failing on a persistent weak layer can be very sensitive, and they might be triggered remotely, from a distance, or worse from below!

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    Fresh drifts formed on weak layers that have developed on the snow surface or preserved under about an inch of new snow. Soft drifts of new snow, up to about a 2 feet deep, could be quite sensitive, and a smaller avalanche overrunning a slope with poor snow structure could create a much larger avalanche. Old, harder wind slabs are fairly widespread at upper elevations near ridge tops and in and around terrain features like gullies, cliff bands, and sub ridges. People could trigger 1 to 3-foot-thick slab avalanches of wind drifted snow on steep slopes, especially where drifts formed on weak, sugary, or faceted snow.

    • Avalanches of wind drifted snow could be triggered remotely or from a distance.
    • Harder wind slabs may allow people to get out on them before releasing.

Special Announcement

We are offering a Backcountry 101 Avalanche education class in Logan on Jan 21 and 22. . Details and registration here.

Check out our new and relevant Blog featuring Paige and Greg discussing Danger Ratings and Persistent Weak Layers....HERE

Thanks to the generous support of our local resorts, Ski Utah, and Backcountry, discount lift tickets are now available. Support the UAC while you ski at the resorts this season. Tickets are available here.

Recent Activity

-Riders reported initiating lots of shooting cracks in lower angled terrain and triggering a small avalanche failing on a sugary persistent weak layer near the ground in Egan Basin, just north of the Idaho State Line.

-We also intentionally triggered a small avalanche yesterday on a test slope just above the Tony Grove Road. The soft slab avalanche on a 38° east facing slope at 7500' was about 20" deep and 30 feet wide.

Snow and Weather

Several inches of medium density new snow fell Monday night in the Bear River Range and strong westerly winds drifted snow onto slopes with widespread preexisting weak layers. About a foot of new snow accumulated at upper elevations, with one inch of Snow Water Equivalent or SWE at the 8400' TGLU1 Snotel in the Central Bear River Range. The heavy new snow and drifting from strong westerly winds overloaded widespread preexisting sugary weak snow and created dangerous avalanche conditions in the backcountry.

We went for a ride to look at the new snow in the Tony Grove Area, and here are the results of some of out tests:

It will be sunny in the mountains today, with 8500' temperatures expected to rise to just under freezing, around 31°F. A west-southwest breeze will keep temperatures cool and create wind chill values as low as -7°F. Clouds will move overhead tonight and there is a good chance for some snow showers in the mountains tomorrow, but less than an inch of accumulation is expected.

Additional Info

Everybody should make time to examine and practice with your avalanche rescue equipment, and convince your backcountry partners to practice with you. Watch our companion rescue video HERE My tip for avoiding avalanches in the backcountry is to keep your slope angles low. Avoid and stay out from under slopes steeper than about 30 degrees. Get a tool to measure slope angle and practice with it in the backcountry. Watch the video HERE.

Paige shows what we are talking about when we mention faceted snow in our forecasts. Watch the video HERE

General Announcements

Visit this website with information about Responsible Winter Recreation by the Utah Office of Outdoor Recreation.

We've kicked off Season 4 of the UAC podcast with a Conversation with American Avalanche Institute owner Sarah Carpenter. You can stream it HERE or wherever you get your favorite podcasts.

The Tony Grove Road is not maintained for wheeled vehicles in the winter.

EMAIL ADVISORY. If you would like to get the daily advisory by email you subscribe HERE.

Remember your information can save lives. If you see anything we should know about, please help us out by submitting snow and avalanche observations....HERE. You can also call us at 801-524-5304, email by clickingHERE, or include #utavy in your tweet or Instagram.

I will update this forecast by around 7:30 tomorrow morning.

This forecast is from the USDA Forest Service, which is solely responsible for its content. The forecast describes general avalanche conditions and local variations always occur.

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