Lawinenlagebericht

East Slopes Central

Northwest Avalanche Center
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Lawinengefahr

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

New snow and wind have created dangerous conditions. It's likely that you can trigger avalanches, where the wind forms drifts of snow and it may now be easier to trigger large and unsurvivable avalanches on deeper weak layers. Minimize your exposure to big avalanche paths and stick to lower angle and well-supported slopes while this winter storm plays out. 

Lawinenprobleme

  • Wind Slabs

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

    Stay off of and well out from under start zones and large leeward avalanche paths. This is not a time to trigger an avalanche in wind-loaded terrain. See more below.

    Strong westerly and easterly winds will form slabs on leeward sides of ridges and terrain features. With up to 8" of recent snow and more expected during the day, winds will have plenty of snow to drift into slabs. While the immediate concern will be for triggering avalanches in these fresh slabs, don't rule out much larger avalanches. Any avalanche triggered in recently drifted snow could step down to more deeply buried weak layers, become very large, and propagate across terrain features. 

    (1/9/2024)

    Look for blowing snow and freshly formed drifts as an indicator of the danger.

    Photo: Joe Dellaporta

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    Put a large buffer of terrain between where you travel and large avalanche paths, especially with leeward start zones and steep wind-loaded features. Only expose one person at a time to avalanche terrain. Stay well out from under steep overhead slopes.

    A problematic snowpack structure exists, and has been speaking to us with signs of instability like whumphing collapses as recently as Sunday. We anticipate these avalanche are becoming easier to trigger, where you find significant new snow and wind drifted slabs. Slab avalanches could be anywhere from 2-4 ft thick and have the potential to propagate widely across terrain features. Unfortunately, this structure is widespread throughout the zone and in many parts of the region. Additionally, a  layer of buried surface hoar from January 2nd sits an inch or two above a crust from December 30th and has been the culprit of several avalanches in the southern part of the zone. Persistent slabs take persistent patience. So, your best mitigation tool will be to stay off of large, steep and or unsupported slopes.

    (1/10/2024)

    Backcountry travelers near Lake Wenatchee remotely triggered this avalanche from a low angle adjacent slope. This avalanche ran on weak, facted snow over the Solstice Crust.

    Photo: Pat Riffie

Avalanche Discussion

On Wednesday, observers in the Wenatchee Mtns reported sudden, easy failures in snowpack tests on old december facets. Near Hex Mtn, an observer reported numerous small wind slab avalanches. Backcountry travelers have continued to report notable signs of instability, such as whumphing collapses and propagating test results. 

Last week's storm dropped about 3ft of snow in much of the East Central, with about 1.5ft in the eastern Wenatchees. NWAC forecasters went to the lower slopes of Cashmere on Saturday and found small faceted grains over a crust above 3,000ft. This is the classic weak structure that can result in a persistent slab avalanche. Another NWAC forecaster visited the Salmon La Sac area last week. At 4600ft, she found around 70cm of new snow with a thin melt-freeze crust from a brief warmup midstorm buried 45cm down. This new melt-freeze crust showed potential for propagation in a snowpack test. Weak snow beneath the Solstice Crust also showed propagation in these test results. The bottom line is that its complicated out there, and its about to get even more tricky. So, it'll be best to take a step back in your terrain selection, and stick to lower angle and well-supported slopes as this next storm plays out.

If you get out, let us know what you see by submitting a public observation!

 

 

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