Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Expect increasing danger on Sunday as a multi-day storm begins to affect the area. Wind slabs could become large at upper elevations, and easily triggered on weaker snow or a recently buried crust. Continue to take a step back, traveling on lower angled and sheltered slopes. 

Avalanche problems

  • Wind Slabs

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

    Wind slabs should become larger and easier to trigger as the day progresses on Sunday. Higher elevations are looking at dangerous conditions towards the second half of the day as new snow and winds build thicker slabs. You could initiate wind slabs at mid elevations and sparsely treed slopes as well. You'll generally find lower danger below treeline.

    Look for active wind transport and increasing snowfall rates as indicators that slabs are forming. Use practical tests to check for signs of instability like shooting cracks as you gain elevation. In many areas you'll still be able to avoid the wind slab problem by steering around stiffer and textured pillows, though at higher elevations you might want to avoid entire slopes.

    (2/17/2023)

    Large cornice indicating prevailing wind direction.

    Photo: Matt Primomo

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–2.5

    A thin weak layer resting on a slick crust from mid-January can be found about 3 feet below the snow surface. The layer was responsible for natural and triggered avalanches from Feb 8-13th. These dangerous avalanches are currently difficult to trigger, but chances may once again increase over the next couple days. If you manage to trigger one, it would be surprising and destructive. The best way to stay safe is to keep your distance from big starting zones that are heavily wind loaded, steep, rocky, or unsupported. Don't expect to receive signs of deeper slab instability with this scenario.

    Default to well-supported terrain features and smaller pieces of terrain. Don't linger for long or take breaks in areas with large, overhead avalanche paths. 

    (2/12/2023)

    Very wide crown spanning most of the south face of Jove Peak. This slide very likely occurred during the middle of the day on Sunday.

    Photo: Public Obs

Avalanche Discussion

The pass picked up 4-6" of snow since Friday, and those amounts are expected to increase substantially over the next few days. Increasing winds and snowfall rates during the day on Sunday will increase avalanche danger. By the time Monday rolls around we're looking at very dangerous conditions as heavy snowfall and strong winds continue. Keep this in mind, and plan your exit accordingly Sunday afternoon.

A notable amount of blowing and drifting snow was observed on Saturday. Stevens Pass Mountain Resort reported ski cutting small but fairly wide wind slab at Gemini Pass, on the windward side the new snow had been scoured down to the recent crust. Further east, the 2/13 crust was thin and breakable, with weaker snow beneath it. Last week, observers in Lanham creek reported weak snow on many surfaces including surface hoar.  Large column tests still indicated the potential for an avalanche to propagate on the MLK crust, 3 feet below the surface.  

The last week brought a widespread cycle of avalanches running on steep, leeward slopes, just below ridges that saw wind loading including Windy Ridge and the Rooster Comb, above Lake Susan Jane. Some of these are suspected to have run on a crust/weak layer about 2.5 feet below the surface. The natural cycle mostly occurred on Feb 8th. A very large avalanche with an impressively wide crown was observed off the S face of Jove Peak on Sunday. It appears this slide ran naturally in the middle of the day with the warming temperatures and sun likely to have played a role in its release. Last Saturday a report came in of a large skier-triggered slab avalanche on a northeast aspect, 5,400ft just north of Lake Josephine. The avalanche ran on the MLK crust, buried in mid-January, almost 3 feet below the surface (see profile image below).

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