Lawinenlagebericht

Mount Shasta

Mount Shasta Avalanche Center
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Lawinengefahr

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

Stormy weather will persist near and above treeline today, and with it, dangerous avalanche conditions. Large natural wind slab avalanches remain the chief concern. Developing wind slabs will exist along exposed slopes and features that encourage drifting. Moist snowfall may lead to increased surface instabilities around steep, convex terrain features. Watch for red flags and use careful terrain management and thorough snowpack evaluation to safely operate in the backcountry today. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–3

    Incoming new snow and strong wind speeds will continue the development of very large and dangerous wind slabs on all aspects above treeline. Furthermore, it is likely that wind drifted snow will develop near treeline, where copious amounts of dry powder snow is available for transport. The wind will craft drifts on all leeward west, north, and east-facing aspects, being most pronounced beneath exposed ridgelines, convex rolls, and open slopes. Cross-loading may be present in northwest facing gullies and chutes. The incoming new snow will certainly add weight to any previously formed drifts, giving them a denser, and more cohesive feel. Watch for blowing snow and cornice orientation to help identify where this problem exists. Feel for denser snow overriding softer snow, as this is a clear indicator that you have found a wind slab. This problem can be avoided by sticking to sheltered or wind-scoured areas. 

     

    (1/7/2024)

    Wind Slab

    Photo: Cory Beattie

  • Loose Dry

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Dry-loose avalanches are all about slough management and hold less of a threat of being buried, and more of a threat of being swept off your feet and dragged through or into consequential terrain. This occurrence will only be possible in very steep and extreme terrain. Although this problem remains possible, it may quickly evolve into more of a storm slab problem as the day advances and moist snowfall accumulates on top of dryer, softer snow. In this case, surfaces will invert, causing slabs of storm snow to become extra ripe for triggering along steep convex terrain features, and in steep chutes and pockets of trees. Use inconsequential test slopes to assess for dense slabs overriding softer snow beneath, and observe for large cracks shooting out from beneath your feet.

    Credit: Univ of British Columbia

    Example of dry loose avalanches

Avalanche Discussion

A NWS Winter Storm Warning remains in effect until 4pm. Another round of wintry weather is here and expected to deliver another healthy serving of snow for near treeline elevations and strong to extreme wind speeds above treeline. Speaking of which, recent observations have all been limited to near and below treeline. Uncertainty remains above treeline in regard to wind effected terrain.

Recent observations from Mount Shasta and the Eddy Mountains have both highlighted a well-structured snowpack with stubborn to unreactive interfaces within the top 40 inches of snow. Today's storm will test the integrity of some of those interfaces.      

The Everitt Memorial Highway and Castle Lake roads remain closed. The timeframe for opening it still unknown.  Alternative access points include McBride Springs, the Nordic Center, Mount Shasta Ski Park, and Pilgrim and Deer Mountain OSV parks. You can ride a snow machine from FSR 31 road (Old McCloud) up to Old Ski Bowl. Please stay in boundaries. Here's a map of the riding boundaries for the Southside of Mount Shasta.

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