Avalanche forecast

Swan Range

Flathead Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

Clearing skies and warm temperatures will cause increasing danger today. Move to less steep or more shaded terrain during the heat of the day or if you see rollerballs tumbling downhill. Limit your risk by choosing slopes where a slide will not carry you over a cliff, through trees, or into a gully. 

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Recent observations have noted moist surface snow on most aspects and elevations. Riders have also reported triggering rollerballs and small sluffs. Today will be sunnier and warmer than the past few days. The strong spring sun can destabilize the surface snow surprisingly fast. Look for signs of an impending wet loose problem, like snow shedding from the trees or roller balls scuttling down steep slopes. These are signals to move to less steep and/or more shaded slopes.

    This problem will develop most quickly when dry snow transitions to wet for the first time, like areas favored by recent convective snowfall. Slopes previously warmed by the sun likely have a series of melt-freeze crusts near the surface, which can delay the onset of wet loose activity.  However, today's forecasted sunshine may be enough to nuke its way through. Plan your route so you are off of and out from under steep, sun-baked slopes during the heat of the day. 

    (3/27/2024)

    Terrain like this steep rocky slope will be the first to produce natural wet loose avalanches.

Avalanche Discussion

Observations from this week indicated a coy wet loose problem that arose during passing windows of sunshine. Clearer skies and warmer temperatures today will make wet loose more menacing today, but not necessarily impressive. The real action should kick off during the ridge of high pressure early next week.

With waning southwesterly winds, we’ve removed the wind slab problem from all three zones. However, I suspect a rider can still find and trigger a wind-stiffened slab in extreme terrain, particularly in areas favored by recent convective snowfall and/or wind. Some areas that come to mind are:

  1. Aeneas Ridge, which routinely sees the highest sustained winds in our forecast area;
  2. The upper McDonald Valley, where Flattop Mountain picked up 7” of snow and 0.7” SWE yesterday
  3. Near the continental divide, where one rider reported widespread wind effect, and another reported a small natural slab avalanche

We’ve dropped the Persistent Slab problem in the Swan Range. Repeated observations, like FAC's from Sixmile, documented that this area’s buried weak layer is non-reactive, and with no reported avalanches, we feel comfortable removing this problem. 

Help avalanche researchers! The Colorado Avalanche Information Center, the Avalanche Research Program at Simon Fraser University, and the U.S. National Science Foundation National Center for Atmospheric Research are researching how skiers, snowmobilers, snowshoers, ice climbers, and anyone else who travels in the backcountry interpret avalanche forecast information. Part of this research includes a specific survey to better understand how useful avalanche forecast information is for trip planning. 

Completing this survey will take approximately 20 minutes. Thank you for sharing your feedback to help us improve avalanche risk communication. 

Regions covered