Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Ongoing warm and sunny conditions continue to develop wet snow problems and dangerous avalanche conditions. The chance of a natural or triggered slide in the surface snow or on a buried weak layer increases throughout the day. Glide cracks and cornices may fail without warning. Keep it simple by sticking to lower-angle terrain without any overhead hazards.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Above-average temperatures, poor overnight refreeze, and intense late-winter sunshine have initiated a natural wet loose avalanche cycle on sunny slopes on Thursday, Friday, and Saturday. This activity continues to creep up in elevation and should be concentrated at the higher elevations and in very steep rocky locations today. This is the fourth day of warming, and snow on shaded slopes may begin to warm and sluff. Triggering a slide in wet surface snow remains likely on any steep slope where the surface does not support your weight or the machine's. 

    This morning’s snow surface may have a thin, unsupportable crust or none at all. Expect natural and triggered wet loose activity to begin earlier than the previous days. Plan your day to stay off and out from underneath steep slopes receiving direct sunshine, including your afternoon exit. Rollerballs indicate the surface is warming and becoming unstable. If you are sinking into a mushy snow surface, move to a different aspect or call it a day. 

    Surface slides could trigger a larger slide on buried weak layers, as described in our Persistent Slab problem.

     

    (2/28/2025) Steep, sun-baked slopes produced multiple wet loose slides on the Swan Front Friday.

    Photo: Chris Gotschalk

  • Persistent Slabs

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

    Balmy conditions continue to stress weak layers (surface hoar, facets, crusts + facets) buried 2-4 feet deep. Natural slides are expected, particularly on slopes directly facing the sun. On steep slopes, riders will likely trigger a large avalanche on any aspect where these weak layers exist.

    Signs of instability like snowpack cracking and collapsing may not be present before triggering a slide. Persistent Slabs can break much wider than expected and be triggered by falling cornices or surface slides involving wet loose snow.

    Over the past two days, multiple wet slabs have been reported due to meltwater moving through the snowpack and affecting the buried weak layers.  Expect these slides to become more likely as the day heats up and water continues to percolate through the upper snowpack.

    Minimize your risk by choosing lower-angle terrain not connected to steep slopes during the extended thaw.

     

     

    (2/28/2025) This slab avalanche was triggered by rollerballs in a cross-loaded gulley. This likely failed as a wet slab.  Note the second crown lower in the path. Photo: Jenny C

  • Glide Cracks

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

    Saturday, at least one glide crack failed as a large avalanche involving the entire season's snowpack. Warm air temperatures and the intense late February sun create meltwater favorable for glide crack failure. The likelihood of slides failing increases with our current warming trend.

    While cracks have been spotted in all aspects at mid and upper elevations, they are concentrated in solar aspects at mid-elevations. The Swan Range is a hotspot with at least 24 visible between Hash Mountain and Wolf Creek.

    This is an unpredictable problem but easy to manage by staying out from under open cracks.

    (3/1/2025)

    This glide crack succumbed to the heat of the day. The resulting avalanche was very large (D3).  Sunday's warm conditions could result in more of these failures.

    Photo: Flathead Avalanche Center

Avalanche Discussion

Saturday was the warmest day of the 2024-25 forecast season, with mid and upper elevation stations reaching 40-49 F and around 60 F on the valley floors. A temperature inversion developed for the second consecutive night, with readings above freezing in the mountains and below freezing in the valleys. It has been 48 hours since stations in southern Glacier Park and the Flathead Range dipped below 32 F.

A poor overnight refreeze and today's expected warm conditions will result in wet snow avalanche problems developing earlier in the day than the past few days. Meltwater is moving through the upper snowpack on solar aspects and is producing wet slab avalanches and at least one glide crack failure, which Rob witnessed in the Swan Saturday. Today is the fourth day that sunny aspects have been warmed, and natural loose activity on these slopes is diminishing at mid-elevations but continues on slopes at higher elevations. The distribution of the wet loose problem may expand to shady aspects where dry snow is still found.  

We are not listing cornice as an avalanche problem, but warming temperatures will weaken these overhanging features and could cause them to fail. A large block trundling down the slope could initiate a larger avalanche on a buried weak layer. Limit time beneath these features and give them a wide berth when traveling along ridges. 

Understandably, there are few observations from parties traveling on snow. One group in the central Whitefish Range noted a large wet slide crossing the Red Meadow road while out (Image). Windshield views note that most of the long avalanche paths on the west side of the Apgar Range deposited debris on the valley floor during the Atmospheric River event. A Swan Front observation noted that rollerballs were even more abundant Saturday and started at the ridge tops above 7000 feet where more wet loose slides were also documented.

Our avalanche problem descriptions often mention that a surface slide (dry or wet loose, wind slab, storm slab) or cornice fall can trigger a much larger avalanche. Observations over the past two days confirm this has occurred recently. Examples include a cornice fall that triggered a slab on a cross-loaded slope (Image), a wet loose that triggered a slab in cross-loaded terrain (Image), and a wet loose that triggered a slab with size D3 debris (Image).

Regions covered