Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Windy conditions may blow the few inches of new snow into slightly firmer and thicker slabs along ridgelines and near exposed features. Steer around smooth pillow-like drifts on steep slopes to avoid triggering one of these generally small avalanches. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Blowing snow, sharp cornices, and drifts behind rocks/trees will help you anticipate wind-loaded aspects Sunday. Since we aren’t expecting a widespread wind slab issue, once you’re near these slopes watch for smooth pillow-like drifts and simply go around them by using lower angled or less wind-affected terrain. You’ll likely find wind-loaded areas along ridgelines, near exposed features, and in rock-walled gullies. Some of these fresh slabs may trigger easily until they have time to bond to the old surface. While we expect most of these avalanches to remain small, in a few isolated areas, you could encounter older deeper slabs that could produce larger avalanches.

    (12/17/2022)

    Blowing snow on the higher peaks Saturday (12/17) showed some signs of wind transported snow. 

    Photo: Katie Warren

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    This problem seems to live in the lower elevations primarily east of Mazama. Often this isn’t the terrain we associate with large avalanches. However, several observations of cracking and collapsing in these eastern mountain environs culminated in a large 500 ft wide avalanche this past week. If you see shooting cracks, feel sudden collapses, or hear whumpfs from the snowpack avoid traveling on or under any nearby steep slopes. In these locations, you may find a layer of weak sugary facets in the lower portion of the snowpack, often under 1 or 2 crusts.

    (12/14/2022)

    Large avalanche crown running across the top of an east-facing slope in Finley Canyon, southeast of Twisp.

    Photo: Public Obs

Avalanche Discussion

Even though we’re entering a more active weather pattern, Sunday’s “storm” won’t bring much snow to the East North region. However, with very cold temperatures, you could see several inches of new snow accumulate by the afternoon. With a wide variety of old snow surfaces reported prior to the storm, you may find the new snow reacts differently from one location to the next. 

Reports from avalanche professionals this week noted surface hoar in sheltered terrain prior to the storm. In exposed areas, the wind knocked these weak grains over. A thin breakable sun crust was observed on steep southerly slopes. While the few inches of new snow shouldn’t pose any real hazard if it bonds poorly to these old surfaces, they could be worth paying attention to as storm totals grow this week. 

In the WA Pass areas, two other notable layers remain in the snowpack. Buried SH (12/8), often found about 8-12 in below the surface, continues to linger but has not been an issue so far. While you may still find the mid-November facets (and crusts) in the lower portion of the snowpack, professionals have not reported any recent significant snowpack test results.

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