Avalanche forecast

Swan Range

Flathead Avalanche Center
View on map

Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
Open full map
Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Stick to wind-sheltered terrain with slope angles less than 30 degrees for today's best and safest riding. Large natural avalanches occurred as recently as Wednesday morning.   Shifting winds have left drifts of snow in unusual locations.  

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3

    Although wind speeds have tapered, they are sufficient to transport the light, fluffy snow that fell earlier this week. Today, you might find wind-affected snow on all aspects as winds transition from Northeasterly to Southwesterly. Watch for scalloped surfaces, pillowed dunes, or a hollow, drum-like sensation under your feet or machine. Move to wind-sheltered terrain for safer riding. 

    (12/21/2022)

    Northerly winds have stripped snow off trees in areas open to the wind. Nearby locations received no wind and still have snow-covered branches.

    Photo: Mark Dundas

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Natural avalanches failed on buried weak layers Wednesday morning.   Whumpfing collapses, and shooting cracks are signs that the snowpack is primed for human triggering. You are most likely to trigger a slide where the snowpack is thinnest, like rocky, wind-scoured slopes or convex roll-overs. The best method for managing this problem is to plan your route to avoid traveling on or under steep slopes - those about 35 degrees or steeper or, for a greater margin of safety, slopes of 30 degrees or more.

    (12/22/2022)

    Crowns from one very large or multiple large to very large natural avalanches at the head of Sheep Creek, south of Mt. Cameahwait. These likely involved wind drifted snow. 

    Photo: Adam Clark/ BNSF

Avalanche Discussion

Maybe I'll go outside today. Things are certainly looking better. A quick glimpse at the weather station table indicates that current temperatures are much improved from Thursday's lows. Stations in the Flathead Range and Glacier National Park are showing increases of 18 degrees Fahrenheit in less than 24 hours, yet they're still well below zero. 

Observations have been understandably sparse during the last two days and consist essentially of two drives up the Highway 2 corridor and Mark snow blowing his driveway. Blase took advantage of Thursday's excellent visibility to survey the aftermath of this week's active weather. He found over a dozen large natural avalanches that likely ran Tuesday night into Wednesday morning when snowfall and winds peaked. While many of these slid on new or drifted snow, several appear to have failed on weak snow near the ground, possibly the November facets. Recent natural avalanches are a reminder that this buried weak layer can produce deadly avalanches given the right trigger. 

Be alert if you're returning to the mountains today. Things might not be the same as you left them before the cold snap. Shifting winds have redistributed the low-density snow that blanketed the region since last weekend, and you can encounter drifted snow in unusual places. Although storm-related instabilities like storm slab, wind slab and dry loose are typically quick to heal, the frigid temperatures we've endured this week have likely slowed this process. Don't count them out yet. Dig down and reacquaint yourself with the November facet layer. It's been a while. Uncertainty is high right now due to limited mountain traffic. Balance this uncertainty by building more significant margins into your trip plan. 

Training: Now's a great time to hone your companion rescue skills. Transceiver parks are open at Whitefish Mountain Resort, one at the summit and one adjacent to Grey Wolf. Both are accessible to snowmachines. You can get more details about training and education opportunities events on our events calendar.

Observations - Thanks to everyone who's been utilizing our new observation submission page. Try it out and help your community by sharing what you see in the backcountry. The form requires you to fill out the location fields and put a dot on a map. Be as specific or vague as you want. Our new Observation View page highlights signs of instability and allows you to filter by date or zone to pull out reports relevant to your objectives.

Regions covered