Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

Dangerous avalanche conditions will develop today. Strong winds will drift new snow into slabs large enough to bury and injure a person. Do your best to find terrain sheltered from the wind and track how much new snow falls throughout the day. Shooting cracks and recent avalanches are bullseye information to keep slope angles less than 30 degrees.

Lawinenprobleme

  • Wind Slabs

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

    New snow and fierce winds out of the west will thicken slabs on the leeward side of ridges and cross-load gullies further down the slope. Expect slabs to become larger and more dangerous throughout the day. Shooting cracks, collapses, and recent avalanches are signs to keep slope angles less than 30 degrees. Stick to slopes sheltered from the wind and pay attention to how much new snow accumulates. 

    (4/3/2022)

    Riders noted the partially filled-in crown of a slab avalanche beneath a ridgeline in the alpine. This may have been triggered by cornice fall or wind loading.

    Photo: burket M kniveton

  • Storm Slabs

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

    If the precipitation forecast verifies, expect a storm slab problem to develop later in the day or tonight. 8 or more inches of new snow or seeing signs of shooting cracks are clues to seek out slopes less than 30 degrees on all aspects. Utilize hand pits and small test slopes to see how well the new snow bonds to the underlying surface. I suspect there will be a window of opportunity this morning to enjoy steeper slopes protected from the wind. Be ready to adapt and change plans if you see snowfall rates exceed one inch an hour. 

    (3/12/2022)

    Steep breakovers (like this one) are common trigger points. Avoid these kind of terrain features if you see signs of shooting cracks or intense precipitation rates. 

    Photo: Andrea Goodrich

Avalanche Discussion

Winter made its return to the Flathead today. New snow begins to trickle in this morning, and snowfall rates will pick up throughout the day. Expect 4 to 8 inches of snow by dusk and up to a foot of new snow by Tuesday morning. Accompanying this snow will be strong wind speeds with gusts reaching 70 mph out of the west.

Freshly falling snow and blowing snow will thicken slabs on leeward aspects. On Sunday, riders observed consistent blowing snow and were able to trigger slabs of drifted snow at upper elevations. New snow will only add more fuel to the wind slab machine, making existing slabs larger and more dangerous throughout the day. Utilize short and inconsequential test slopes to assess how well the new snow bonds to the underlying surface. If you trigger a small slide or get shooting cracks, you found the problem, and your solution is to keep slope angles less than 30 degrees. 

Only on rare occasions do we list both Storm Slab and Wind Slab on the same day. Uncertainty with the timing of the precipitation today is making it one of those days. The bulk of the precipitation is forecast to arrive late today or this evening, so this problem may not develop until tonight. However, if the storm comes early to the party or overproduces, expect slabs to form on all aspects. Assess snow accumulations consistently throughout the day, and be ready to adjust your plans if you see intense snowfall rates. 

The National Weather Service issued a High Wind Warning for our region. Watch for blowdown and use extra caution while driving. There is a chance for lightning later in the day.

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