Boletín de aludes

East Slopes North

Northwest Avalanche Center
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Peligro de aludes

Mon
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Heightened avalanche conditions exist at all elevations on the heels of a warm and wet storm. Wet avalanches are possible at low elevations. You may be able to trigger avalanches on older weak layers though the distribution is uncertain.

Problemas de aludes

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Wet avalanches could still occur where the snowpack remains moist and weak. In the valleys and low foothills east of Mazama, the shallow snowpack may remain wet. Higher into the mountains, temperatures should cool enough to begin to freeze surfaces that were wet. Loose avalanches can be forceful enough to be dangerous. Use caution where you find wet, unsupportive snow or deeper weak layers below that have become wet. Stay well out from under large terrain features with wet snow.

    (1/14/2023)

    Upper Mazama Valley- ENE flank of Driveway Butte, towards Jack's Trail on Methow Trail System

    Photo: Public Obs

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Winds may have been strong enough to form subtle drifts and thicker slabs on leeward slopes. Look for stiffer, dry snow surfaces or hard-over-soft layering in the recent snow. Avalanches may be bigger and more likely above treeline. steer around pillowed or wind sculpted features. Watch for shooting cracks and test slopes that slide easily. If you see these clues, stick to slopes under 35 degrees. 

    (1/5/2023)

    An example of a triggered wind slab avalanche from last week. Liberty Bowl, SW, 7,450ft.

    Photo: NWAC Public obs

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1.5–2.5

    The weight of the recent snow may have stressed buried persistent weak layers. You're most likely to find these in wind-sheltered terrain and sparse trees. We suspect buried surface hoar from around January 5th and possibly weak snow above the Christmas crust could be problematic weak layers. Watch for long shooting cracks and audible collapses as you travel. Digging snow pits and looking for propagating test results can help you identify these weak layers in top 2-3 feet of the snowpack. 

    Three recent avalanches may have involved older weak layers, though none have been confirmed- On Jan 8th, a skier was caught but uninjured in a slab avalanche near Varden Creek. On Jan 10th, a skier triggered a large slab avalanche on a north aspect at 4,800ft near Silverstar Creek.  Finally, snowboarders triggered a deep and wide avalanche on a southeast aspect at 6,180ft near Cutthroat Creek on the 12th (see photo). While there's much uncertainty, all of these avalanches appear to have run on older layers of snow. We should take this as bullseye or red flag clues to use caution and assess the snowpack.

    (1/12/2023)

    Avalanche crown. Triggered while traversing a ridge and experiencing a whumphing collapse. ~2ft deep by 100ft wide. SE, 6,180ft.

    Photo: Ben Starkey

Avalanche Discussion

A significant cycle of wet avalanches occurred on Friday into Saturday in the lowland hills. On Saturday, an observer near Driveway Butte reported hearing avalanches running and saw very large wet avalanche debris. Friday morning, I saw a couple of small wet avalanches that ran to the ground on a steep bank north of Methow (see below). WSDOT forecaster reported a wide avalanche (~600ft) in the SR 153 corridor near Carlton. An observer reported that a large avalanche put debris on Twisp River rd near the intersection of Poorman's Creek rd. Observations in the higher into the mountains are still limited. If you see avalanches, please submit an observation.

On Friday, observers near Cutthroat Creek reported upside-down, heavy snow. Below 5,000ft the snow was moist, though precipitation remain snow down to at least 4,000ft. On Thursday, I went to the Twisp River drainage to look for persistent weak layers. While ee didn't find anything that obviously pointed to the danger, we trigger surface instabilities and saw the beginning of the warm up. At 4,900ft, north aspect, we found tilt tests failing down 10" on an interface from around January 5th. This layer could harbor surface hoar in other locations. We found sudden planar tests and propagating results within the Christmas crust matrix (CTM (SP), ECTP 31).

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