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Forecast for the Logan Area Mountains

Toby Weed
Issued by Toby Weed on
Monday morning, December 13, 2021
Strong winds created CONSIDERABLE avalanche danger in some areas. People are likely to trigger slab avalanches of wind drifted snow at upper elevations where strong south winds have created stiff drifts. Avalanches in north facing terrain may fail on a persistent weak layer and could be triggered remotely, from a distance, or below.
  • People should avoid travel on or under steep drifted slopes at upper elevations.
  • Southerly facing and lower elevation terrain was bare or very shallow before last week's storm, so avalanches are unlikely and the danger is LOW.
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Weather and Snow
This week's storm deposited around 16 inches of new snow on upper elevation slopes in the Logan Zone. South winds increased yesterday and are cranking along the ridges again this morning, with gusts of nearly 60 mph. It will be mostly cloudy and windy again today, with high temperatures at 8500' around 31°F. A south wind will blow along the ridges at 17 to 24 mph, with gusts as high as 40 mph. The winds will continue to drift the fresh snow at upper elevations creating stiffer and hard wind slabs, dangerous avalanche conditions exist in some areas, and people are likely trigger avalanches on steep slopes.
At the highest elevations in the Logan Zone, the fresh snow stacked up on few inches of loose sugary faceted snow capping a very hard rain-crust from mid November. Sunny slopes up high and most terrain at mid and lower elevations were still bare of snow before the storm.
Belle making her way up to the wind-swept saddle. The strong south winds were funneled through the notch and scoured all the snow down to rocks.
Recent Avalanches
A skier reported triggering loud audible collapses and extensive cracking near Steam Mill Peak yesterday.
Skiers triggered a small slab avalanche of drifted storm snow on Cornice Ridge Saturday. It was on a north facing slope at around 9300', about 20' wide and 15" deep.

Another party reported triggering a few audible collapses and remotely triggered from below a small slab avalanche that cracked and moved a bit but did not run.
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Avalanche Problem #1
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
The CSI Logan Peak wind sensor at 9700' shows increasing and strong south winds overnight and this morning..
  • People are likely to trigger slab avalanches of wind drifted snow at upper elevations where the strong south winds are creating stiff drifts. Avalanches could be 1 to 2 feet-deep.
  • Watch for and avoid stiff recently drifted snow in and around terrain features like gullies, sub-ridges, and cliff bands.
  • ​​​​​ Even small avalanches could be quite dangerous due to very shallow snow conditions.
Strong south winds drifted the fresh snow into stiff drifts in exposed terrain.
Avalanche Problem #2
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
In some north facing upper elevation terrain, avalanches of wind drifted snow from the recent storm are likely to fail on a persistent weak layer consisting of sugary faceted grains.
  • Audible collapsing or "whumpfs" are a sign of unstable snow and of an active persistent weak layer problem.
  • Cracking in the snow surface is a sure sign of unstable snow.
  • Avalanches failing on this persistent weak layer could be triggered remotely, from a distance, or below.
Greg sent in this picture of his snowpit from near the top of Beaver Mountain on Friday (12-10-2021). Note the larger sugary faceted grains just below the nice fresh powder.
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. Yesterday, some people drove 4-wheel-drive vehicles up to the lake, but conditions were apparently getting rather sketchy up high.
General Announcements
  • Check out all the upcoming education classes and clinics HERE.
  • Please submit your observations from the backcountry HERE.