Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
1 · Gering
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

At upper elevations, isolated slabs of wind drifted snow remain sensitive to your weight or the weight of your snowmachine. These may be hard to detect, because much of the snow in this terrain has been affected by recent winds. Sheltered, shady, mid-elevation slopes offer soft snow, better riding, and less hazard.

Lawinenprobleme

  • Wind Slabs

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

    The surface snow on many - most - upper elevations slopes was drifted, scoured, pressed, packed or scalloped by Monday and Tuesday's winds. Do your homework before committing to slopes steeper than about 35 degrees in this terrain. Dig or probe into the snow to check for wind-hardened snow more than about 8 inches thick. Test these hard slabs to see how well they're bonded to the soft snow or crusts below them. Slope cuts, however, can get you into trouble; hard slabs are notorious for breaking well above a person. Shooting cracks are a give-away that these slabs are unstable.

    (3/9/2022)

    This large avalanche likely failed during the last snow and wind event early in the week

    Photo: Clancy Nelson

Avalanche Discussion

Goldilocks conditions - juuust right - may be tough to find today. Your best bet is probably sheltered, shady slopes at mid-elevations, where 6-12 inches of soft snow has accumulated above a very hard crust left by last week's atmospheric river.  Only a few inches of snow covers this crust at low elevations, making for difficult travel. Upper elevations harbor isolated slabs of recently-drifted snow large enough to bury or injure a person. These may be hard to detect amidst the mostly wind-damaged snow reported in the Lake McDonald area Wendesday, and the Swan Range Tuesday.

There are exceptions to this general picture. Much more snow has accumulated in the Whitefish Range in the past week, particularly in the northern half. Tuesday, Guy and I found last week's crust buried by over two feet of recent snow at 6500 feet. The wind-affected snow we saw was limited to a ridgeline, and a party east of WMR that day reported similar conditions.  However, wind speeds picked up in the Whitefish Range late Wednesday, and are still blowing near or at speeds strong enough to transport snow. So I expect some of the soft snow at the surface in the Whitefish Range has been drifted into slabs near ridges and in the tops or edges of terrain that readily collects wind-blown snow, like chutes and gullies. My guess is that slabs large enough to be dangerous remain isolated. 

A warm, windy, and eventually wet southwesterly flow arrives this weekend. The system may bring enough new snow to change conditions and increase the avalanche danger. 

The Friends of The Flathead Avalanche Center and FVCC are hosting the last Intro to Avalanches next weekend. And on March 22, join us online for a Community Chat where we review recent conditions and debrief a near miss. 

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