Lawinenlagebericht

Banner Summit

Sawtooth Avalanche Center
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Lawinengefahr

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

Kernpunkte

You're most likely to trigger a large, wide avalanche on steep slopes facing the northern half of the compass. Watch for and avoid fresh, stiff wind drifts, and anticipate loose snow avalanches in very steep terrain.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–2.5

    Recent storms built 2-2.5' thick slabs above weak layers of facets and facet + crust combinations. Observations indicate that these layers are most likely to cause trouble on steep middle and upper-elevation slopes facing the northern half of the compass. 

    Before triggering an avalanche, you may not experience obvious signs of instability like snowpack cracking and collapsing or whumpfing. Avalanches could be triggered remotely, from lower-angle terrain above, below, or to the side of steep slopes. Persistent Slabs can release in surprising ways and break much wider than expected. 

    The best way to manage this problem is to stick to lower-angled slopes and simple, forgiving terrain free from terrain traps like cliffs, trees, or creek bottoms. 

    Additional Discussion: Today's snowfall and moderate wind may form thin, fresh wind slabs in areas exposed to the wind. Look for these near ridgelines and along steep mid-slope gullies. Cracking is a great indication that you've found a sensitive slab. 

    (3/18/2025) A wide, slab avalanche near Banner Summit on Bull Trout Pt. E @ 8,500'. Photo: Sawtooth Avalanche Center

Avalanche Discussion

Today's avalanche concerns fall into two buckets:

Old snow: Tuesday, skiers in the Fishhook drainage of the Sawtooths triggered a large avalanche on a steep, N-facing slope. Prior to triggering the slide, they noted collapsing in wind-loaded terrain along the ridge. The slide was triggered from the lower angled terrain approximately 50' away from where it released. This triggered slide fits the pattern of observed natural avalanche activity, as well as reports of unstable test results on the northern half of the compass. 

New snow: This morning's small storm may form a fresh, thin batch of wind slabs. These may be particularly sensitive where they form over crusts from recent sunshine. If you're venturing into very steep terrain, loose snow avalanches could be large enough to knock you off of your feet. If the sun makes a prolonged appearance, expect this morning's new snow to peel from steep, rocky slopes. 

Keep your eyes and ears open for obvious signs of instability. Recent avalanches, muffled collapses, or cracking at the snow surface are your best indications that the slope you're on or connected to may be unstable. When in doubt, dial back your terrain choices; there's plenty of meadow ripping and low-angle powder to be found. 

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