Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
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Lawinengefahr

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

Kernpunkte

New and wind-drifted snow falling on a weak snowpack will increase the avalanche danger. Steer away from wind-affected surface snow or dune-shaped features along ridges, open bowls, or mid-slope gullies. Choose low-angle terrain if you find 8 or more inches of new or wind-drifted snow. 

IF the incoming storm arrives earlier than expected, the danger will rise to CONSIDERABLE. The avalanche danger will increase tonight due to heavy snowfall. We have issued an AVALANCHE WATCH for all zones. 

 

Lawinenprobleme

  • Wind Slabs

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

    Yesterday (Thursday), southwesterly winds increased enough to drift snow onto leeward slopes at upper elevations. Several parties in the Flathead Range reported blowing snow, and one group in JFS Canyon found hard slabs of wind-drifted snow that produced audible collapses and shooting cracks 40 feet long. 

    Today, an uptick in winds and fresh snowfall will continue to build wind slabs.  Look for signs of wind-affected snow along exposed ridges, open bowls, and downwind from prominent terrain features. Rippled snow surfaces or dune-shaped features are obvious indicators. Soft slabs cracking around your feet are a clear sign of unstable snow and should usher you to slopes that are less steep or more sheltered from the wind. Hard slabs will support your weight and may not give signs of instability until it is too late.  

    If the incoming storm arrives early, expect to find soft slabs on all aspects and elevations, including wind-sheltered terrain.  The old snow surface is remarkably weak, and the resulting slabs will be difficult to manage as they can:

    • Break much wider than expected, or well above you.
    • Wrap around terrain features into adjacent start zones.
    • Be remotely triggered from low-angle or flat terrain.

    (1/30/2025)

    We triggered shooting cracks up to 40 feet in length with audible collapses in wind-loaded terrain off the ridge.

Avalanche Discussion

We have issued an AVALANCHE WATCH this morning. This means we have all the necessary ingredients to develop dangerous avalanche conditions in the next 24 hours. 

Today marks the end of a long stretch of cold, clear, and dry conditions. Although we have enjoyed mostly stable avalanche conditions, this pattern has left us with a variety of weak snow and crusts at and near the surface of the snowpack. A couple of observations of wind-drifted snow failing on weak surfaces during the last week are hints of what’s to come (obs1, obs2). Pockets of wind-drifted snow, like these, will be the primary hazard until today’s storm arrives.

Snowfall is expected to start this afternoon and will cause the avalanche hazard to increase rapidly. This will be a dramatic change from the previous few weeks and requires a dramatic change in terrain selection. Bring this mindset to the backcountry today in case the storm arrives earlier than forecasted. Be prepared to fall back to low-angle terrain if you notice storm snow stacking up quickly.

Because the incoming storm is driving the avalanche hazard, we've removed Glide Avalanches from the list of problems. However, glide cracks still littler the landscape and they can fail seemingly at random. Avoidance is the best way to manage this hazard. Don't park, play, lunch, etc., below slopes where glide cracks are present. 

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