Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Recent snowfall and wind continue forming slabs of wind-drifted snow on various slopes. You could encounter both hard and soft slabs which will be larger and more widespread as you gain elevation. Cracking in the surface snow directs you to lower-angle or sheltered terrain where the snow quality is better.  

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2.5

    You can find several generations of wind slabs on various aspects formed by this week's shifting winds. Saturday's snowfall, which favored the Whitefish and Swan Range, may become the newest addition. Slabs are soft and hard and are found in usual and 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 exposed to the wind. However, atypical winds may have left slabs in unusual locations at lower elevations. 

    Wind-drifted surfaces may resemble dunes or have a pillowed appearance. Etched surface snow (Image) indicates wind scouring. Cracking or collapsing (whumphing) are signs of a sensitive slab directing you toward lower-angle slopes.

     

    (2/7/2025) Crown of a wind slab avalanche in Path 1163 that likely ran overnight on February 5.                    Photo: Adam Clark

Avalanche Discussion

Saturday's storm overproduced in the Swan and Whitefish Range, where 5-10 inches of low-density snow was recorded at stations.  The WMR snow report is stating that this 10 inches is the largest 24-hour snowfall of the season.  Water amounts during this storm were relatively small, with around 0.5 inches of SWE recorded. The Flathead Range and Glacier Park stations report just an inch or two of new snow.

The new snow adds weight and possibly cohesion to this week's low-density surface snow. Friday, we listed Persistent Slab as an avalanche problem in the Whitefish Range. Due to the generally soft surface conditions, a rider is unlikely to trigger a slide on a buried weak layer; however, as the surface snow consolidates into a slab, the likelihood of triggering increases. Observations suggest that buried surface hoar is more widespread in this range than in the other zones. Observers noted collapsing on southerly slopes in Canyon Creek during their ascent and descents yesterday (Observation 1, Observation 2). This may be a sign that the surface snow is becoming more cohesive.

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. Mostly cloudy conditions are expected today, but natural loose snow slides may develop on steep slopes facing the sun if the intense February sun makes a prolonged appearance.

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