Lawinenlagebericht

East Slopes Central

Northwest Avalanche Center
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Lawinengefahr

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

As we add more snow to a sensitive snowpack expect dangerous avalanche conditions to follow.  Triggering a shallow slab avalanche could result in a larger avalanche in older snow that breaks widely around terrain features. Thursday is a good day to avoid all large open slopes steeper than 30 degrees at mid and upper elevations.  

Lawinenprobleme

  • Persistent Slabs

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

    While you are more likely to find a shallow storm slab on Thursday, it's the lurking, larger persistent slab avalanche that grabs your attention and makes you think twice about your terrain choices.  Persistent slab avalanches are dangerous and can catch even the most experienced backcountry travelers by surprise.  They can break widely around terrain features and be triggered from lower angle slopes. As the snow piles up, the potential for larger avalanches that break down to a facet-crust combo increases. 

    On Wednesday, forecasters in the Lake Wenatchee area were finding weak sugary snow (facets 1.0-1.5mm) 8-14" above a firm crust in the near and above treeline elevation bands.  The depth to the persistent weak layer could more than double by the end of Thursday.  On Monday, observers in the Highway 2 corridor near Lost Lake, as well as close to Stevens Pass, reported collapses up to 100ft in diameter and snowpack tests that indicated propagation.

    Keep your terrain selection conservative Thursday and avoid open slopes above 30 degrees at mid and upper elevations. 

    (12/14/2020) Observers found 8 inches of snow over a facet crust combo near Lost Lake, a depth that has become deeper during the week. They reported whumphs as big as 100ft across on this weak layer.

  • Storm Slabs

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

    With 6-12 inches of snow in the forecast through Thursday afternoon, you can trigger a storm slab avalanche on convex rolls or very steep terrain.  Look for shooting cracks as you travel and use small test slopes to test the stability of the new snow. In areas where firmer wind-affected snow is present, look for new cornice formations and wind rolls to ascertain which slopes below ridgelines may have been recently loaded.  While a new snow avalanche could take you for a ride, think about the consequences if one steps down to deeper layers. 

    (12/16/2020) Shooting cracks give you a clear signal of slab avalanche potential. Photo: Dirty Face Mt.

Avalanche Discussion

The active weather pattern continues this week as we incrementally load the snowpack along the east slopes of the Cascades with each passing storm. 

The avalanche danger continues to vary greatly across the zone, with the higher hazard on the west side closer to the Cascade Crest. In the Wenatchee Mountains near Blewett Pass and the eastern foothills of the Cascades, you may find less dangerous conditions along with less snow.  Expect shallow snow cover at low elevations and bare ground particularly on low south-facing slopes. Typical early season hazards can be expected with open creeks, stumps and rocks. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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