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 8 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

As today's snowfall stacks up, the likelihood of triggering an avalanche increases. This is more likely at upper elevations and on wind-loaded slopes. Shooting cracks or hollow sounds are clues that you have found an unstable slab. Give the snowpack time to adjust and minimize stepping too far out as we transition from a widespread natural avalanche cycle.

Lawinenprobleme

  • Storm Slabs

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

    4-8 inches of new snow will fall throughout today (Friday) and land on a variety of surfaces, including wet snow, dry snow, and crusts. As you gain elevation, snow totals will increase, and slabs will thicken on the leeward sides of ridgelines in wind-loaded terrain. 

    Cracking around your skis or machine indicates you have found an unstable slab.

    Use terrain as your map through the mountains today. Steer around steep(greater than 30 degrees) convex rollovers. Sidehill travel may be difficult due to a hard supportable crust. Dry snow sliding on a slick crust can move fast and travel further downhill than expected. 

    New daytime snowfall, laid ontop of a crust will be possible to trigger on steep convex rollovers today. 

    Photo: CJ Cummings

Avalanche Discussion

The Atmospheric River that impacted Northwest Montana has shifted southward. It triggered a widespread natural avalanche cycle across all aspects and elevations. Temperatures have dropped below freezing in most areas. Yesterday (Thursday), Josh and Mike noted that the snow surface at Whitefish Mountain Resort was starting to freeze. Stations in John F. Stevens Canyon are reporting temperatures near zero this morning.

The resulting crust will act like a new ground surface as it freezes. Areas that remained at or above the snowline could have multiple feet of recent snow. Areas above 7,000 feet will lack a substantial crust. Travelers who find themselves in these upper elevations will be treated to winter-like conditions, as opposed to the carnage-strewn slopes below. Below 7,000 feet, the new snow will rest upon a stouter crust; thus, a slicker bed surface for any resulting avalanches.

Dry snow conditions create an impetus to use terrain as a risk-management tool. Treat steep, upper elevation slopes with more than 6 inches of snow as suspect. Hollow-sounding snow, or dunes below a ridgeline, means that you have found a pocket of wind-loaded terrain. Cracking around your skis or machines should clue you into storm snow instabilities. Use this information to pick a route that limits exposure to slopes with a similar-looking shape, aspect, and elevation.

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