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Forecast for the Logan Area Mountains

Toby Weed
Issued by Toby Weed on
Friday morning, December 17, 2021
There are areas with CONSIDERABLE danger in the backcountry, where people are likely to trigger dangerous avalanches. Avalanches in north facing terrain may fail on a buried persistent weak layer and could be triggered remotely, from a distance, or below. People could trigger slab avalanches of wind drifted snow in exposed terrain, as well as soft slab and loose avalanches of storm snow on steep slopes. Natural avalanches are possible, particularly during periods of heavy snowfall this morning.
  • People should avoid travel on or under steep drifted slopes at upper and mid elevations, especially those facing the north half of the compass.
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Weather and Snow
Expect another cold and snowy day in the mountains today, with single digit temperatures, fairly strong westerly winds, and wind chill values as low as -11° F. A few more inches of accumulation is possible on upper elevation slopes this morning. About a foot of powder stacked up in the Central Bear River Range in the past 24 hours, and the Beaver Mountain webcams show heavy snow falling this morning.
Winds blowing out of the west drifted plenty of snow in exposed terrain overnight, and drifting will continue to build wind slabs on the downwind side of major ridges and in and around terrain features. Dangerous avalanche conditions exist in the backcountry, mainly in northerly facing upper elevation terrain where avalanches could fail on a buried persistent weak layer. Human triggered avalanches are likely and natural avalanches are possible especially during periods of heavy snowfall this morning.
***Sunny slopes up high and most slopes below about 8000' were bare of snow before last week's storm.
Recent Avalanches
Wednesday, I came across a couple natural avalanches near Tony Grove Lake, which occurred during the storm overnight Tuesday night. The avalanches that were around a foot deep failed on a buried persistent weak layer of sugary faceted snow under last week's storm snow.
This natural avalanche above the southwest corner of Tony Grove Lake is about a foot deep and 100' wide, NE, 8300'
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Avalanche Problem #1
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
In north facing terrain above about 8000', some avalanches are likely to fail on a persistent weak layer consisting of sugary faceted grains. Wednesday, I triggered several large and loud collapses in low angled terrain and around rock out-crops as I traveled in untracked snow west of Tony Grove Lake.
  • Audible collapsing or "whumpfs" are a sign of unstable snow and of a persistent weak layer problem.
  • Cracking in the snow surface or shooting cracks over distance are a sure sign of unstable snow.
  • Avalanches failing on this persistent weak layer could be triggered remotely, from a distance, or below.
I triggered a loud whumpf on the flats and this thin crack formed about 60' away from me.
Avalanche Problem #2
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
The CSI Logan Peak wind sensor at 9700' shows continuing strong winds blowing from the west this morning and certainly drifting tons of fresh powder into avalanche starting zones.
  • People are likely to trigger soft and harder slab avalanches of wind drifted snow at upper elevations where west winds continue to create and deepen drifts and wind slabs.
  • Avalanches of wind drifted snow could be 1 to 4 feet deep.
  • Wind slab avalanches could fail on a persistent weak layer, and might be triggered remotely. (Cracking and collapsing are red flags.)
  • Avoid recently drifted snow in and around terrain features like gullies, sub-ridges, and cliff bands.
Avalanche Problem #3
New Snow
Type
Location
Likelihood
Size
Description
People could trigger soft slab and loose avalanches of storm snow in steep terrain. Avalanches could fail on density changes or other weak layers within the storm snow itself.
  • Natural avalanches are possible during periods of heavy snowfall, like this morning.
  • Even small avalanches could be quite dangerous due to very shallow snow conditions.
Additional Information
  • Always follow safe backcountry travel protocols. Go one person at a time in avalanche terrain, while the rest of your party watches from a safe area.
  • Check your avalanche rescue equipment, change your batteries, and practice often with your backcountry partners.
  • Be very careful, keep your speed down, and stay in control. Encounters with shallowly buried rocks or down trees in the early season have led to many season-ending injuries.
  • The Tony Grove Road is not maintained for wheeled vehicles in the winter season.
General Announcements
Get free batteries for your transceiver and a chance to win 1 of 10 Black Diamond Rescue Kits, 1 of 3 Mammut Barryvox transceivers, or 1 of 3 BCA Tracker transceivers. Stop at a participating shop, fill out our survey and get a free set of batteries. Don't need batteries, but still want a chance to win? Simply fill out the survey to be registered. Promotion runs through December 19.
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  • Please submit your observations from the backcountry HERE.
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