Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
4 · High
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

This may not be your run-of-the-mill storm day. Avalanche danger will rise throughout the day and could become very dangerous in the afternoon. Natural avalanches may release particularly during periods of heavier precipitation. Stay off of slopes over 30 degrees and avoid traveling below large avalanche paths descending from the higher peaks.

Avalanche problems

  • Storm Slabs

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

    It might not be that dangerous right out of the gate on Sunday. Slabs will be thinner and might only show  short cracks. However, as snow totals grow, things could become quite spicy. When and where the scale might tip is very hard to say. 

    These new slabs will build on a highly variable surface. Firm crusts, textured snow, scoured slopes, surface hoar, and facets were all reported prior to this storm. This could cause slopes to react very differently from one spot to the next. If avalanches fail on facets or surface hoar, they could release on lower angled slopes and break widely. Hand pits, uptrack tests, and small slopes can give you a glimpse into how the snow will react. However, it might be very different than the next slope you touch. Instead of trying to thread this needle, stay off of slopes greater than 30 degrees and avoid avalanche terrain entirely at upper elevations. You could start to see natural avalanches releasing from wind-loaded areas and during periods of heavy snowfall. 

    With the strong and gusty winds, slabs will be larger and more dangerous at upper elevations and along exposed ridgelines.

    (12/8/2023)

    Example: You may see shallow storm slabs failing as an early warning sign of more dangerous slides to come. 

    Photo: Alpental Pro Patrol

  • Loose Wet

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

    Near and below the rain-snow line, you’ll find plenty of wet heavy snow. While the snowpack at these lower elevations has been through a lot, it’s hard to ignore this much rain. Be extremely leery of punchy snow on any steep slope. It probably won’t give you many other clues until it’s flowing downhill like a slushy. 

    While these slides should be generally small, if they catch you, they will carry you wherever they go. That could be over a cliff or into a creek.

    (1/4/2024)

    Example: Wet snow may push downhill especially near the rain-snow line. 

    Photo: Dallas Glass

Avalanche Discussion

This is a tricky forecast. All the elements are there, heavy precipitation, strong winds, fluctuating temperatures, and potential weak surfaces. However, the storm is a bit warm. The new snow could just glue into place, or we might see a more widespread natural avalanche cycle. Or both. Either way expect the avalanche danger to increase as you ascend in elevation and as the day progresses.

The new interface (2/24) varies by aspect. On Saturday, NWAC staff near Snow Lake watched as surface hoar was buried intact on northerly aspects by 1cm of moist heavy snow. At this same interface in other areas, facets and settled powder were found. On southerly slopes, the new snow quickly bonded to the surface crusts. Make sure to look right at and just above this interface while testing the snowpack. 

To make things more complex, the upper snowpack still contains various recent weak layers and interfaces. In shaded terrain, several layers (2/19, 2/14, 2/11) were clearly visible above the Early February Crust (EFC), about 2-2.5ft below the surface. Profiles at 4500ft suggest these layers are healing, but higher in the terrain, we have much greater uncertainty. It’s not out of the question that an avalanche could step-down into one of these older weak layers in larger upper elevation slide paths. On more sunny aspects, the upper snowpack over the EFC is thinner and much stronger. While one of these much larger avalanches would be rare, take it into consideration before spending time below alpine start zones.

Regions covered