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Forecast for the Logan Area Mountains

Toby Weed
Issued by Toby Weed on
Friday morning, December 31, 2021
The avalanche danger is HIGH on upper and mid elevation slopes facing northwest through east, with large natural and human triggered avalanches likely. People are likely to trigger dangerous deep slab avalanches failing 3 to 5 feet deep on a buried persistent weak layer near the ground. Recent drifting and plenty of new snow created dangerous avalanche conditions on steep slopes at all elevations. People could trigger slab avalanches of wind drifted snow in exposed terrain, and loose avalanches and shallow soft slabs of storm snow are likely on any steep slope with significant deposits of new snow.
  • Avoid travel on or under slopes in the backcountry steeper than about 30°.
  • Conditions are much safer and quality powder riding can be found in sunny low angled terrain.
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Learn how to read the forecast here
Avalanche Warning
AN AVALANCHE WARNING HAS BEEN ISSUED FOR THE MOUNTAINS OF MUCH OF THE STATE OF UTAH, INCLUDING THE WASATCH RANGE...BEAR RIVER RANGE...UINTA MOUNTAINS...AND THE MANTI-SKYLINE.
THE AVALANCHE DANGER IS HIGH FOR THE WARNING AREA AND TRAVEL IN AVALANCHE TERRAIN IS NOT RECOMMENDED.
HEAVY SNOWFALL AND STRONG WINDS HAVE CREATED VERY DANGEROUS AVALANCHE CONDITIONS. BEING CAUGHT IN ANY AVALANCHE IS LIKELY TO BE UNSURVIVABLE. STAY OFF OF AND OUT FROM UNDER SLOPES STEEPER THAN 30 DEGREES.
Weather and Snow
Looks like about 10 more inches of snow overnight and it's still snowing this morning in the Bear River Range. The two-day storm total at the 8400' Tony Grove Snotel site is now over 2 feet, with 2.8" SWE. The Holiday storms brought several feet of snow to upper elevation slopes, and the station recorded 7.6" of SWE in the last week (since 12-23). Strong southwest winds from yesterday and overnight moderated a bit and veered from the west-northwest this morning, with a 20 mph average wind speed at the 9700' CSI Logan Peak weather station. I'm reading 14°F at Tony Grove and 7°F at Logan Peak.
Expect more snowfall and cold wintry weather today in the mountains, with another 3 to 7 of accumulation possible, and continued drifting from moderate west winds. Temperatures are expected to drop to around 7°F at 8500', with wind chill values around -13°F.
Recent Avalanches
Amy found some recent natural activity on the Logan Temple grounds yesterday. We should start paying attention to the snow at lower elevations after the recent very cold temperatures....
No one reported any new avalanches in the mountains in the past couple days, but there were a few large naturals that occurred early in the Christmas storm cycle. We think these failed on a buried persistent weak layer and occurred on upper elevation north facing slopes late on or around 12/24, (Christmas Eve), but the crowns and debris from these avalanches was all blown in and covered up by a couple feet of new snow when we looked at them on Tuesday.
  • Check HERE for all the latest observations and avalanche activity.
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Avalanche Problem #1
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
Dangerous deep slab avalanches breaking on a persistent weak layer near the ground are likely for people to trigger. This layer of weak, sugary facets can be found in north facing terrain 6-12 inches above the ground just above a hard ice crust that caps old snow from October and early November. Avalanches failing on this layer will likely be 3 to 5 feet deep and may break hundreds of feet across. Avalanches could still be triggered remotely from a distance, or worse, from below.
  • Audible collapses or "whumpfs" and shooting cracks are red flags indicating unstable snow and a lurking persistent weak layer.
Richie sent in this short video of a compression test with eye opening results in the Beaver Mountain Backcountry.
Avalanche Problem #2
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
During the recent storm, strong southwest and west winds were blowing as heavy snow fell, drifting tons of weight onto vast lee side slopes, some plagued by a buried persistent weak layer near the ground. Winds blowing from the south, southwest, and west have been transporting tremendous amounts of snow during the last several days. Monday the winds dropped down into the terrain, and this week we observed significant drifting at all elevations. The wind slabs appear to be well bonded the the fresh snow in most areas, but in some areas, especially around terrain features where drifts form, people are likely to trigger avalanches.
  • Winds during the storm drifted snow directly onto slopes that have a persistent weak layer of sugary facets near the ground. Wind slabs will make avalanches breaking on the facets larger, deeper, and more deadly.
  • Avoid travel on and under steep drifted slopes.
  • Drifts and wind slabs form on the downwind side of major ridges and in and around terrain features like sub-ridges, gullies, and cliff bands.
  • These appeared to be bonding pretty well yesterday, but avalanches of wind drifted snow are possible where there is no apparent faceted persistent weak layer. Avalanches at any elevation could fail on a density change within drifted new snow or on a thin, or a not-so-obvious weak layer.
Avalanche Problem #3
New Snow
Type
Location
Likelihood
Size
Description
About two feet of nice powder snow fell on many slopes in the Logan Zone in the past couple days and more is quite possible today. Soft slab and loose avalanches of fresh storm snow are likely in steep terrain and possible at all elevations. Natural avalanches are most likely during periods of intense or heavy snowfall and drifting. Stay out from under steep slopes and be aware of potential terrain traps and trees below you if you venture onto steep slopes even in sheltered areas.
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
General Announcements
Who's up for some free avalanche training? Get a refresher, become better prepared for an upcoming avalanche class, or just boost your skills. Go to https://learn.kbyg.org/ and scroll down to Step 2 for a series of interactive online avalanche courses produced by the UAC.
  • Check out all the upcoming education classes and clinics HERE.
  • Please submit your observations from the backcountry HERE.
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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