Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
View on map

Avalanche danger

Wed
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Out of date — this forecast expired 4 years ago.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

Good and safe riding conditions are found on slopes sheltered from the wind and less than 35 degrees. Recent avalanches and whumpfing collapses tell us we are not out of the woods yet, and it remains possible to trigger a large avalanche failing 1 to 3 feet deep. Recent moderate winds formed slabs of drifted snow on aspects that face south and west. 

Avalanche problems

  • Persistent Slabs

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

    Loud audible collapses and unstable pit results plague the observation page and are clear signs to not trust sleep slopes. The only way to manage this problem is through careful route selection. I will continue to keep slope angles low, give steep rollovers a wide berth, and avoid dawdling in the runout of large avalanche paths. Persistent slabs are notorious for remote triggering and breaking surprisingly wide.

    (12/10/2022)

    Low angle terrain like this provided great turns with little exposure to the Persistent Slab avalanche problem.

  • Wind Slabs

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

    North and east winds drifted snow into slabs most commonly found on south and west aspects. Although I suspect slabs are relatively thin and stubborn to trigger, larger fetches may produce slabs large enough to injure a person. Dune-shaped drifts and rippled surfaces are clues to where this problem hides. Steer your machine and point your boards towards wind-sheltered slopes.

    (12/9/2022)

    Early season cornice formation cross-loading slopes.

    Photo: Mark Dundas

Avalanche Discussion

Today should be another beautiful day to spend in the mountains. The sun will be out (hopefully), winds will be light, and many slopes remain untracked. Avoid adding mental stress to this beautiful day by taking time this morning to make a plan. Here are a few suggestions:

-Select an area with low slope angles. Utilizing a slope angle shading map (like this one) can help you plan that part of your day.

-Select a route that keeps you out from underneath large avalanche paths. 

-Identify aspects that may have gotten loaded by recent east and north winds. Ridgelines and gullies that face south and west will be suspects for slabs of drifted snow.

Once you get into the mountains, identify steep breakovers and give them a wide berth. Another terrain feature that I’m wary of is steep road cuts. Both terrain features may be impossible to identify on a map, thus requires constant attention while out in the mountains. 

Why am I suggesting so many steps to planning out a day? When dealing with a nagging persistent slab problem, terrain management is our only option. We can do most of the “work” at home, which allows us to focus more on the finer points of terrain management while we are out.  Here are a few good examples (observation, observation) of recent observations where people stuck to their plan and it resulted in a great day in the mountains.  

The common theme to observations is the rumbling collapses observers continue to report. These collapses, or whumpfs, are when the weak layer collapses beneath a slab of snow. The missing ingredient when the weak layer collapses and doesnt trigger an avalance is commonly a slope steep enough to slide. Slope angle and terrain management is the key to safely managing a persistent slab problem.

Education - Our next Avalanche Awareness presentation is tonight, Tuesday, December 13, at Whistling Andy Distillery, Bigfork. The next presentation is on Wednesday, December 14, at Penco Power Products, Kalispell. You can get more details about these free 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