Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Additional snowfall and gusty winds could result in a fresh crop of Wind Slabs for you to manage by Sunday afternoon. Look for actively blowing snow creating larger mounds that you should avoid. You could encounter wet avalanches on steeper slopes where the snow surface is moist and sticky.

Avalanche problems

  • Wind Slabs

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

    Another round of snow and wind should strike the Snoqualmie Pass zone on Sunday. Look for actively blowing snow creating fresh cornices and deeper drifts as you ascend in elevation. You could encounter wind-loaded features near ridgelines or rocky terrain such as confined gullies or the base of cliffs. Just because slabs weren’t reactive first thing in the morning, doesn’t mean they’ll be like that all day. They may be more likely in the afternoon hours as the wind direction changes and speeds increase. This should coincide with a period of heavier snow showers. Regardless of the time of day, you can use small test slopes to see how the snow is reacting to your weight and look for textured surfaces or areas that look “fat” to help you identify the wind-loaded features you should avoid.

    (1/29/2023)

    Visual clues of wind-loading and Wind Slab development.

    Photo: Andy Harrington

  • Loose Wet

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

    The snow at low to mid-elevations was heavy and damp in many areas of the zone on Saturday. We received numerous reports of Wet Loose activity, with at least one slide as large as D1.5. Fluctuating freezing levels Saturday night and Sunday may not be enough to stiffen up the moist surface, so let’s keep these slides on our radar again on Sunday. 

    If you encounter wet and punchy snow surface conditions and notice fresh rollerballs/pinwheels or snow shedding from rocks, then you should be on the lookout for Wet Loose avalanches on steeper slopes. These slides like to start at a point and then fan out as they move downhill, collecting snow and growing in size as they descend. They are fairly simple to manage, just head for slopes under 35 degrees, keeping aware of what's above you.

    (2/4/2023)

    A D1.5 Wet Loose avalanche on the north side of Mt. Snoqualmie was observed on 2/4.

    Photo: Ian Nicholson

Avalanche Discussion

Snoqualmie Pass picked up anywhere from 4-8” of snow from Friday afternoon through Saturday morning, with increasing depths as you ascend in elevation or in wind-loaded terrain. Multiple reports from Saturday indicate that the snow surface is heavy and wet, at times overlaying drier snow from earlier on in the storm (upside-down). The storm snow loses moisture content as you ascend in elevation, but some parties reported that it was moist all the way to ridgeline. 

This resulted in mostly wet avalanche problems as opposed to dry ones on Saturday. Rollerballs and small Wet Loose avalanches were reported by recreationalists, NWAC forecasters, and avalanche professionals at the Pass proper. The storm snow is suspected to have fallen on a variety of surfaces, including firm crusts, wind-pressed snow, and weak, faceted snow. On Saturday, NWAC forecasters observed moist snow reluctantly sliding on a firm crust on steeper test slopes. On Mt. Snoqualmie, a larger (D1.5) Wet Loose was reported by avalanche professionals. We do not have any confirmed avalanches on buried weak snow at this time, but on more shaded and wind-protected slopes, you could find isolated areas primed for surprising avalanches failing on these faceted grains. 

We anticipate Saturday night’s snowfall to bond fairly well to the wet and warm surfaces, but as snow showers and wind speeds are renewed in the afternoon hours, you may see more slab development. The incoming snow will further increase the load on the 3/2 interface and we anticipate the majority of avalanches to occur at or above this layer. We are still watching some deeper layers above the MLK crust, but do not think this storm will be the one to tip the scales.

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