Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

It will be easiest to trigger avalanches in the new snow above treeline. Wet avalanches are possible at low elevations. You may be able to trigger large avalanches on older weak layers at mid and upper elevation though the distribution is uncertain.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Winds have been strong enough to form subtle drifts and thicker slabs on leeward slopes. Wind transport may drop off after morning. 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. In wind-sheltered terrain, you can trigger small loose avalanches in the new snow. If the sun comes out, expect loose avalanches on steep, southerly slopes.

    (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

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    Put plenty of space between where you travel and large start zones. 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. 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 the top 2-3 feet of the snowpack. 

    In the past week, four avalanches have involved older weak layers: 1/8- a skier was caught in a slab avalanche near Varden Creek. 1/10- a skier triggered slab avalanche N, 4,800ft near Silverstar Creek. 1/12- A snowboarder triggered slab avalanche on SE, 6,180ft, Cutthroat Creek (see photo). 1/15- A snowmobile triggered slab avalanche on facets near the ground. While there's much uncertainty, all of these avalanches appear to have run on older layers of snow. The most likely weak layer in the western half of the zone is buried around January 5th, potentially surface hoar. While less likely, there's also weak snow around the Christmas crust as well as on the ground in the eastern mountains. These avalanches are 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

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    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. Rain continues to make its way to low elevations from the east, often exceeding forecasts over the last few days. Higher into the mountains, temperatures have cooled enough to begin to freeze surfaces that were previously 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

Avalanche Discussion

On Sunday, observers in the Highway 20 corridor near Washington Pass reported blowing snow above treeline along with loose dry avalanches in steep terrain. At least one of these triggered a small slab avalanche. 

A significant cycle of wet avalanches occurred on Friday into Saturday in the lowland hills. Large wet avalanches gouged to the ground on a west aspect around 4,000ft of Pole Pick Mountain, east of Twisp. 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 Thursday, I went to the Twisp River drainage to look for persistent weak layers. While we 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).

Regions covered