Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
2 · Mässig
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Triggering an avalanche in wind-affected snow remains possible. This will be more likely where the wind has stiffened the snow surface near ridgelines and summits. You can reduce your chances of finding trouble by choosing slopes with a softer surface sheltered from the wind.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Shifting winds and light snowfall overnight and through today may contribute to developing fresh, thin slabs. Several generations of slabs are found on various aspects formed by the past week's shifting winds. Slab density ranges from soft to hard and may be found near ridgelines, summits, and cross-loaded gullies. Recent atypical winds may have left slabs in unusual locations. 

    Slabs rest on weak snow formed during the January dry spell, recent low-density snowfall, or older wind slabs. This could contribute to slabs being more sensitive and propagating further than expected. Slabs become more widespread as you gain elevation and enter open terrain.  

    Wind-drifted surfaces may resemble dunes or have a pillowed appearance. Etched surface snow indicates wind scouring. Cracking or collapsing (whumphing) are signs of a sensitive slab directing you toward lower-angle slopes. However, hard slabs may support your weight and not offer signs of instability until they fail. 

     

    (2/13/2025)

    Very hard wind scalloped snow near an upper elevation ridge. This is an obvious clue that you are in wind-affected terrain and may be in the vicinity of a wind slab.

    Photo: Flathead Avalanche Center

Avalanche Discussion

This week's bitter cold temperatures have moderated as snowfall returns to the Flathead for the weekend. Snowfall through Saturday morning is generally light and low-density but may aid in fresh wind slab development. A more potent storm arriving Saturday night and lasting through Sunday could increase the avalanche danger, particularly in the favored Swan Range.  Unfortunately, both systems' energy stays well south of our area. 

Cold temperatures and a relatively dry February have left us in a holding pattern regarding the Persistent Slab problem. The surface/near surface snow remains cohesionless in many locations, limiting the ability for a failure on buried weak layers to propagate. Reports of collapsing (whumphing) and propagating snowpit tests continue to trickle in. As the surface consolidates into a slab, this problem will become more widespread and dangerous. This weekend's snowfall may contribute to the development of a surface slab. Other factors that aid in stiffening the surface include wind, warming temperatures, or sustained sun. 

The recent low-density snow and cold conditions have kept a cohesionless surface in many sheltered locations. On very steep slopes, riders could trigger loose snow sluffs. These can be problematic above cliff bands, in long-running gullies, or terrain traps where the snow piles up deep.

Upcoming Events: Check out our calendar and sign up now!

  • February 20-22nd: Avalanche Safety: Introduction to Avalanches Human Powered for Skiers and Snowboarders - register here
  • Feb 26th - Pint Night at Blackstar with donations going to Flathead Avalanche. State of our Snowpack presentation at 7pm! 

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