Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
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Lawinengefahr

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

Rising temperatures will increase the avalanche danger. Rollerballs or pinwheels are precursors of a Wet Loose avalanche problem. Although Wet Loose avalanches can be easy to identify and avoid, natural avalanches may become large enough to injure a human. Move to shadier aspects or to lower angled slopes if you see signs of wet avalanche activity. 

Lawinenprobleme

  • Cornices

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

    Today's hot weather put Cornice Fall back on the menu. Be cautious and observant while walking on and near exposed ridgelines. Give the edge of ridgelines a wide berth and use vegetation or rocks as visual landmarks for safe travel. Avoid traveling directly below ridgelines with large cornices.

    (3/11/2024)

    Warm temperatures and solar radiation may cause cornices to fail naturally. Give terrain directly below a wide margin for error. 

    Photo: Cam Johnson

  • Loose Wet

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

    Warm temperatures and clear skies will wet the snow surface and cause it to slide. South-facing terrain that is steep and rocky is typically the first to show signs of warming. The simplest advice is to move to less steep terrain once you observe rollerballs or small sluffs. You can also move to shadier aspects, though keep in mind the sun angle is high this time of year and north-facing slopes also receive solar radiation. Today may be hot enough to cause those slopes to slide as well. 

    (3/31/2024)

    This pile of wet loose debris originated over 1000 feet above in the upper-elevation band. New snow warmed and slid on 3.29 or 3.30. This pile is the result of two or more slides merging. 

    Photo: Mark Dundas

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    2–3

    Avalanche activity on a weak layer buried 2-4+ feet below the surface has diminished over the last couple of weeks. Although the likelihood of triggering a very large avalanche is low, the consequences are high.

    The last reported Persistent Slab avalanches occurred during a period of intense heat, like today and tomorrow. Although we still anticipate the problem to be unlikely, this history should be taken into consideration. The safest bet is to give terrain where the problem exists a wide margin for error. That terrain is rocky, steep, upper-elevation slopes that face north.

    (3/9/2024)

    The crown of a hard slab avalanche on a northeast aspect at ~7,000ft. This likely failed on a layer of facets above the early February crust. Steep, rocky, shaded terrain is the terrain where this problem still exists. 

    Photo: Ernesta McIntosh

Avalanche Discussion

The past few days of intermittent sunny skies with cold nights have eased the transition into wet snow avalanche problems. Southerly aspects received a couple of melt/freeze cycles, which will slow the onset of natural avalanche activity today and provide a window for safer travel. 

Freezing levels will climb to roughly 8,000 feet today and possibly upwards of 10,000 feet tomorrow with sunny skies. Natural avalanche activity will occur as the day progresses but should be relatively easy to manage and avoid. 

Timing is your friend today and tomorrow. An early start and exit will be the safest approach to both days. Here are a couple of tips to help plan your day during diurnal melt/freeze cycles.

  • Plan your route to avoid exiting on or beneath avalanche-prone terrain during the afternoon heat. Terrain that faces south and west will be most likely to avalanche. Strategically planning your route can reduce the chances of being forced to cross beneath a slope that is ripe for avalanching. 
  • Time your day to be up and down before the snow surface becomes wet and gloppy. If you feel your feet or machine sinking into wet snow, then it is time to accept defeat and stay off steep slopes.

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