Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

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

Snow, warming temperatures, strong winds, and dangerous avalanche conditions will ring in the start of the holiday week. You are likely to trigger avalanches in wind-drifted snow on Monday, and some avalanches could be large and run farther than expected on slick crusts. Avoid steep wind-drifted ridgelines and choose low-angle, sheltered slopes for recreation instead. 

Avalanche problems

  • Wind Slabs

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

    Strong winds drifting snow onto slick crusts will likely create reactive wind slabs. To identify wind-loaded slopes, look for actively blowing snow, cornice formations, and pillowlike drifts. Avoid steep ridgeline terrain, confined alpine features, and steep gullies, all likely spots for wind slabs to form. Rain to upper elevations formed a melt-freeze crust on the surface (Solstice Crust), which was recently buried by a few inches of snow. Avalanches could run farther and be larger than you expect on this slick surface. 

    The warming temperatures forecasted during the storm will layer heavier snow over lighter snow, and you could also find sensitive storm slab avalanches running on the Solstice Crust. These avalanches will likely be small, but it is also worth traveling conservatively in sheltered terrain. Even small avalanches could push you into obstacles or cause injuries that ruin your season. Precipitation and winds will begin to taper on Monday morning, so expect the most sensitive avalanche conditions in the first part of the day. 

    (12/22/2023)

    Fresh drifts with cracking in steep ridgeline terrain.  

    Photo: Willie Webster

  • Loose Wet

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

    Rollerballs and wet, heavy snow that you're sinking into are signs that wet avalanches are possible, and you should consider low-angle routes. While wet loose avalanches tend to be more predictable than slab avalanches, they could slide easily and run farther than you anticipate on the Solstice Crust. Stay vigilant about managing your terrain and where you stop, start, and travel in relation to your backcountry partners. 

    Wet, heavy snow falling on slick crusts between 3500-5000ft and some sunshine on Monday morning could make wet avalanches quite reactive. Small, steep test slopes are a great way to observe how the snow reacts and determine if you're dealing with wet or dry snow avalanche problems. 

Avalanche Discussion

We are going into a stormy pattern with fluctuating freezing levels for the holiday week. While it isn't the blower powder we are all used to skiing up in the East North Area, it will begin to stack up and help with overall coverage. Expect significant accumulations throughout the week at elevations above 4500-5000ft. Sunday night is the first in this series of storms and will be a good test for how reactive avalanches will be on the Solstice Crust. The warmer overall temperatures could help form a favorable bond with this crust, or the few inches of snow that fell on Sunday could have weakened with cold overnight temperatures, but it's too soon to say.

Near Blackpine Lake on Thursday, observers reported small avalanches failing on a layer of buried surface hoar. The distribution of this problem is uncertain, and observations indicate that this is not a problem in the Highway 20 corridor or the Hart's Pass area. However, these avalanches are evidence that the eastern portion of the zone may hold a more complex snowpack with avalanche concerns that could linger for an extended period of time. Pay attention to red flag signs of instability, such as whumping collapses, and consider digging down to identify the telltale grey line in the snowpack that clearly distinguishes surface hoar layers. 

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

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