Avalanche forecast

Logan

Utah Avalanche Center
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Avalanche danger

  • Alpine
  • Treeline
  • Below treeline
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Highlights

The avalanche danger is CONSIDERABLE where strong winds and recent snowfall have created dangerous avalanche conditions. Human-triggered avalanches are likely. Any natural or human-triggered avalanche can be 1-3' deep, and over a hundred feet wide.

Elevated conditions also exist in sheltered terrain and on steep lower and mid-elevation slopes, where people could trigger small soft slab avalanches.

Evaluate snow and terrain carefully, make conservative decisions, and avoid slopes with recent deposits of wind-drifted snow steeper than about 30° Pay attention to changing weather patterns. As this next storm system develops, it will bring new snowfall, warm temperatures, and elevated winds. This will cause the already weak snowpack to only become increasingly sensitive.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    3

    The situation is very simple - there is a persistent weak layer (PWL) of faceted snow from roughly 16 days of clear and cold weather in November that now has 1-3' feet of snow on top of it. Over the last few days, this layer has begun producing both small and large avalanches. As we continue to add more snow, and more wind to this weak layer we will only continue to see larger and more destructive avalanches occurring.

    • We've found buried soft sugary snow at all elevations and on slopes facing every direction. The persistent weak layer (PWL) problem has the potential to get worse as widespread slopes with poor snow structure are overloaded, and the problem is likely to be an issue for a while.

    • Areas plagued by a very sensitive PWL consisting of buried feathers of surface hoar are also widespread, but we've found them mostly in sheltered low and mid-elevationon terrain. Persistent weak layers consisting of surface hoar are notoriously tricky, often surprising and sometimes catching experienced avy pros off guard. Avalanches failing on buried surface hoar may occur on lower angled slopes than you might expect.
    • Red Flags indicating PWL instability will include audible collapses or wumpfs and shooting cracks. Slab avalanches failing on a buried persistent weak layer are likely to be remotely triggered from a distance, hopefully from above or from an adjacent slope, and not from below.

    Monday's snow fell on bare ground or very shallow snow on low and many mid elevation sunny slopes, (W, SW, S, SE) so the danger of avalanches is lower (Moderate), but potential might be higher for hitting rocks.

    Video from our field day yesterday near White Pine Knob where we were able to find the weak faceted snow beneath the recent snowfall.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3

    People are likely to trigger dangerous slab avalanches of stiffer wind drifted snow failing on a sugary buried persistent weak layer if they venture onto exposed upper elevation slopes. Drifts and wind slabs may be hidden under fresh powder. Natural avalanches are possible today as more fresh snow is drifted onto steep overloaded slopes.

    • Wind slabs often form on the lee side of exposed ridges and in and around terrain features. Watch for and avoid drifts on gully walls, under cliff bands, along sub-ridges, in scoops, saddles, and sinks.

    • Drifted snow is stiffer and more compacted than non-drifted snow. Last night's strong winds created harder drifts (called hard slabs if they avalanche). Hard slabs are often stubborn, notorious for allowing people to get out on them before releasing, kind of like a mouse trap!
    • Slab avalanches of wind drifted snow failing on a persistent weak layer might be triggered remotely, from a distance, or even below!
    • Today you should avoid travel on or under steep slopes with deposits of wind drifted snow.
    • Freshly formed wind slabs can be quite sensitive and are often remotely triggered.
    • Shooting cracks in drifted snow are a sure sign of instability.

Special Announcement

Our annual party and fundraiser is coming up on December 6 in Logan at the Cache. 19th Annual Utah Avalanche Center Pray for Snow Party and Fundraiser information and tickets HERE.

Join the Utah Avalanche Center and the Division of Outdoor Recreation to celebrate the Fourth Annual Avalanche Awareness week, from December 4 - December 11. Click HERE to view the full list of events for the week.

Recent Activity

Yesterday multiple parties submitted reports of recent avalanche activity in the Logan area mountains.

  • Tony Grove Road - E Aspect - 6500' - Soft slab avalanche failing on SH buried 12" deep - 12/2
  • Logan Peak/Fair Grounds Bowl - E Aspect - 9500' - Hard slab avalanche failing on a buried weak layer of facets 2.5' deep - 12/2 (See image below list)
  • Beaver Creek Canyon - W Aspect - 7400' - Soft slab avalanche failing on a buried weak layer of facets - 12/2
  • Red Pine Ridge - E Aspect - 9000' - Cornice triggered hard slab avalanche failing on a buried weak layer of facets - 12/2
  • Three Terraces - E Aspect - 9000' - Cornice triggered hard slab avalanche failing on a buried weak layer of facets - 12/2
  • North Face of Providence Peak - NE Aspect - 9300' - Hard slab avalanche failing on a buried weak layer of facets 2' deep - 12/2 (See the second image below list)
  • Logan Dry Canyon - N Aspect - 7600' - Soft slab avalanche failing on surface hoar - 12/3
  • Mezzanine - NW Aspect - 7500' - Soft slab avalanche failing on a buried weak layer of facets 14" deep - 12/3
  • Mount Naomi Wilderness - W Aspect - 9200' - Hard slab avalanche failing on a buried weak layer of facets - 12/3
  • West side of Egan Basin - E Aspect - Soft slab avalanche failing on a buried weak layer of facets - 12/3
  • Grandfather Cornice - E Aspect - 9400' - Cornice triggered hard slab avalanche failing on a buried weak layer of facets 3' deep - 12/3 (See the third image below)

See our updated list of observed avalanches from across Utah HERE

Snow and Weather

Dangerous avalanche conditions exist in the backcountry. Last week's heavy snow and drifting overloaded widespread slopes with buried persistent weak layers and poor snow structure. Dangerous human-triggered avalanches are likely on drifted upper and mid-elevation slopes. Nearly all parties reported triggering heart-stopping audible collapses or "wumpfs" and shooting cracks Friday and yesterday as they traveled through the new snow at mid and upper elevations. These are "bulls-eye" red flags indicating unstable snow and real potential for dangerous slab avalanches failing on a persistent weak layer.

This morning, skies are overcast with a trace amount of water being picked up by remote weather stations. No measurable accumulation yet. Temperatures are in the mid to upper 20s F, the wind is now blowing from the southeast between 20-30 mph with gusts near 40 mph.

Today will remain overcast with snowfall beginning late morning and into the early afternoon. Temperatures will climb into the upper 20s F, and winds will transition more south-southwesterly averaging speeds of 10-20 mph, with gusts up to 30 mph at upper elevations. 2-4" of accumulation is expected before this evening.

Tonight, snowfall should continue with the intensity increasing a bit. Between 4-8" of additional overnight accumulation is possible on upper elevation slopes by Monday morning.

Additional Info

  • Take the all-new online avalanche courses the UAC built for Know Before You Go or take other online courses listed on the KBYG website (Develop skills -> Online Learning).
  • Get your avalanche rescue gear ready for winter. Put fresh batteries in your transceiver and update the firmware. Inspect your shovel and probe. Get your airbag backpack ready by possibly doing a test deployment and update the firmware if it is an electric version.

General Announcements

Please submit your observations from the backcountry HERE.

For a list of avalanche classes from the Utah Avalanche Center go HERE

For information on where you can ride your sled or snowbike, check out this map of the winter travel plan for the Tony Grove and Franklin Basin Areas HERE.

The Tony Grove Road and other forest roads in the Logan Ranger District are not maintained for wheeled vehicles in the winter.

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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