Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

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

Be prepared for frigid temperatures and deep snow if you head into the mountains on Monday. The snowpack will need some time to adjust to the recent load, so stick to conservative terrain as you gather information. Avalanches should be largest in wind-loaded terrain and easier to trigger on convex slopes, near rocky features, or on slopes over 35 degrees. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Wind-loaded terrain continues to be the most likely location for you to trigger a large avalanche. Although the winds haven’t been impressive compared to past storms, it doesn’t take much to transport snow this light and fluffy. Several rounds of Wind Slabs likely formed during the storm parade, particularly at upper elevations near ridgelines or at the base of cliffs, sides of gullies, and in rocky chutes. Some of these slabs may be easy to spot while others may be hidden under a few inches of storm snow. Feel for subtle differences in the firmness of the snow as you travel or look for freshly built cornices and big drifts to help identify wind-loaded terrain. Once you identify a slope to be wind-loaded, avoid it by choosing an alternate route.

    (12/23/2021)

    A small skier triggered soft slab on a wind-loaded convexity.  SW, 4800', SS-AS-R1-D1-S

    Photo: Robert Hahn

  • Storm Slabs

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

    With storm snow totals approaching 4 feet, it goes without saying that the sheer volume of snow accumulated over the past few days can be hazardous. We continue to receive reports of shallow and isolated soft slabs, which is why we are categorizing these new snow problems as Storm Slabs. Depending on where you are recreating, Dry Loose avalanches could also be a fit to capture the hazard presented by the recent storm snow. The management of these two issues should remain largely the same, regardless of your categorization of them. You can look at the upper snowpack to see if you are dealing with slabs or loose snow by using upslope tests to look for cracking, or quick hand pits and test slopes to look for failing blocks of snow. These signs would all point toward slab avalanches compared to loose avalanches. No matter which problem you are dealing with, be suspect of slopes over 35 degrees where loose snow could knock you off your feet. These slides could occur naturally if snow is shedding from trees and rocks or could be human triggered.

    (12/22/2021)

    You can dig with your hand to look at the new storm snow and search for potential weak layers or slab development.

    Photo: Andy Harrington

Avalanche Discussion

On Sunday, we received a second-hand report of a large avalanche in the Chair Peak basin area of Alpental Valley. The report indicated that the debris ran far and wide and contained some small broken trees. Although all the details are not clear, this observation highlights the amount of uncertainty that surrounds upper elevations and the potential for large avalanches. Due to the continued stormy weather, observations from higher elevations have not occurred since at least Wednesday, December 22. 

What we do know is that close to 4 feet of snow has fallen since December 22 and that the Solstice Crust exists in many locations at the base of this 4 feet of snow. Additionally, a layer of weak graupel exists over 2 feet down in the snowpack, and although it has not produced any known avalanches, it certainly has that ability.

On Monday, temperatures will be the coldest of the season, so be prepared to dress appropriately. Low elevation snow has accompanied the cold temperatures and therefore trailheads further west in the zone could have more snow or ice than usual. With so much light and fluffy snow, falling and not being able to get up is a real hazard. Give tree wells a wide berth, keep your partner in sight, and learn more about snow immersion hazard here.

Regions covered