Bollettino valanghe

Flathead Range & Glacier NP

Flathead Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
1 · Debole
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In sintesi

Enjoy the beautiful day while realizing avalanche conditions remain tricky. Saturday's large, remotely triggered slide confirms that the troublesome buried weak layers remain reactive. Continue using a conservative mindset by sticking to low-angle terrain not connected to a steep slope. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    Two prominent buried weak layers were the culprits in multiple natural and human-triggered avalanches over the past few weeks. The slopes most susceptible to triggering a large avalanche are on NW-NE-S aspects, where the surface hoar and facets exist 1-4 feet deep.  

    This week’s wind event (image) drifted snow onto the same aspects that harbor the buried weak layers, stressing them with a substantial load and keeping the danger elevated. This process was partly responsible for a large, remotely triggered slide from the bottom of a slope in the southern Whitefish Range on Saturday (see accompanying image) (observation).

    Snowpit test scores show that it is becoming more difficult to affect the weak layers, but yesterday's avalanche and collapses indicate the snowpack cannot be trusted.

    Stick to low-angle slopes without overhead hazard if traveling on NW-NE-S aspects. Recent crowns have reached into low slope angles, confirming that riders should remain well back from the edge on ridgelines or above convexities. Southwest and west aspects are the best options for limiting your exposure to this problem.

    (2/28/2026)

    This large, hard slab was triggered by a rider from flat terrain at the bottom of this steep slope. The crown depth is estimated at 3 feet and is likely to have failed on the preserved surface hoar layer. 

    Southern Whitefish Range

Avalanche Discussion

High pressure has entrenched itself over the Flathead, bringing mild temperatures and plenty of sunshine through Tuesday. On sunny slopes, expect to find a surface crust this morning, which will break down during today's warming and sun. 

The current warming trend, coupled with the recent wind event, is stiffening the surface slab on sun- and wind-exposed slopes. In these locations, the slab's strength may limit your ability to impact the weak layers (image), and you may not see signs of instability, such as cracking or collapsing (whumphing), before triggering a slide.

In sheltered areas, the slab is softer and may give you clear signs that you have found a sensitive slab. Saturday, riders in the southern Whitefish Range chose low-angle sheltered powder to play in, which was a wise choice as they had several collapses (observation).

Despite fewer signs of instability reported this week, the snowpack structure remains poor. The Patrol Fund Level 1 class, the FOFAC Intro to Avalanche class, and an experienced observer had propagation in snowpits on Saturday in the southern Whitefish Range (observation, observation, observation). The experienced group was picky about their slope selection and generally avoided avalanche terrain. They did not experience any collapses, but their test results confirmed to them that it was an appropriate day to be picky. 

Wind slabs: Powerful SW winds (image, image) on Wednesday through Friday redistributed loose surface snow into stiff slabs on wind-exposed slopes. These features will be a mix of soft and hard slabs and will increase in thickness as you gain elevation. These should be generally stubborn to trigger, but it is worth evaluating any wind-loaded slopes before committing.

Loose Wet: Warm and sunny conditions will melt surface snow, develop rollerballs, and possibly small wet loose slides. Following the wind event, we don't think there is enough loose snow on the surface for this to be a problem. If you are sinking into the snowpack more than a few inches, move to a shaded aspect or choose a slope that does not end in a terrain trap.

 

 

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