Lawinenlagebericht

East Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
2 · Mässig
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 3 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Conditions are challenging with a breakable crust in all but the highest elevations. If you manage to get above the rain line you might still be able to trigger a slab avalanche. Travel cautiously in the crust,  and look for signs of instability like whumphing collapses or shooting cracks before committing to steeper alpine terrain.

Lawinenprobleme

  • Wind Slabs

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

    The recent storm laid down 1-2ft of new snow, but it ended warm with light rain up to at least 6,000ft in much of the zone. Here above the crust, you could still trigger large slabs on steep  terrain features. If you make it up high, this is a great time to dig a snow profile. Look for weak layers in the snowpack, and test how recent layers are bonding. The storm snow may be resting on slick crusts and surface hoar in some areas. You can also use quick hand pits to look at layering. Small, inconsequential test slopes may also help when looking for instabilities like shooting cracks. Consider steep slopes near ridgelines with thick looking drifts or small cornices. Other features to identify for caution are mid-slope convex rolls, cross loaded gullies, and steep slopes beneath cliff bands. Steady winds drifted the snow into deeper slabs, so be observant of surface texture and feel as you travel. 

    (12/10/2023)

    Mission Ridge Avalanche control produced 2ft deep wind slabs that ran on the 12/7 crust. 

    Photo: Drew Carlton/ Mission Ridge Patrol

Avalanche Discussion

On Saturday evening an impressive storm brought 8-20 inches of snow across the East Central. The majority of the precipitation fell as snow, but the storm ended warm and it rained to at least 6,000ft. The rain line may be slightly lower as your go further north and east in the zone. A widespread wet loose cycle was recorded at lower elevations, and some avalanches even occurred within the Leavenworth city limits,  right next to the middle school. This is a great reminder that all it takes for an avalanche is a slope steep enough, unstable snow, and a trigger. Up at higher elevations, control work at Mission Ridge resulted in large wind slabs that ran on a crust from December 7th, 2ft deep. A number of small wet loose avalanches were also reported from middle elevations around the Salmon la Sac and Blewett Pass. With clearing skies and cooling temperatures, most slopes should freeze solid and limit the avalanche danger to upper elevations.

Our uncertainty liese at higher elevations, once you get above the rain crust. What elevation does it extend to? Is the storm snow/wind drifted snow bonding poorly to slick old crusts or buried surface hoar? These are all questions to answer if you find yourself up in the alpine with this fairly benign weather. Don't commit to larger slopes before first seeing how the snow reacts on smaller, lower-consequence slopes. As you travel, carefully observe and look/listen for signs of instability like collapsing or shooting cracks.

Many creeks ran high and may have washed over roads over the past week, so you might find yourself riding over rock on some access roads. Windward slopes have been blown down to rock in many areas. You could still hit buried rocks, stumps and other obstacles with the shallow snowpack.

You can add to the forecast! Please let us know what you see in the mountains by submitting an observation.

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