Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

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

Steer around wind-drifted features and pillows on slopes 35 degrees and steeper. You can trigger avalanches where the wind drifted snow, and you may even encounter dangerously deep avalanches on older weak layers.  With the uncertainty of triggering deeper layers at upper elevations, put a large buffer between where you travel and steep slopes where avalanches can start or run down from above.

Avalanche problems

  • Wind Slabs

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

    You're most likely to trigger avalanches where the wind has drifted the recent snow into stiffer slabs. The wind should taper off for Sunday, so you'll need to look and feel for signs of drifting from the past 24 hours. You can steer around wind-loaded features and slopes over 35 degrees at middle elevations.  However, this isn't a sound strategy at upper elevations. There, conditions are doubly dangerous as there's a chance of triggering very large and destructive avalanches on deeper layers. See more below.

    Take time to test the recently accumulated and drifted snow on inconsequential slopes before traveling in terrain steeper than 30 degrees. With all the recent snow, be aware of falling in treewells and keep your partners in sight.

     

    Looking over towards the wind affected west aspects of Lichtenburg. 

    Photo: Joe Dellaporta

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    These avalanches can be very dangerous, difficult to predict, and can give little warning. The best way to manage them is to avoid avalanche terrain where the weak structure exists. Stay off of and far away from steep avalanche paths above 6,000ft. Avoid traveling in areas with complex, overlapping avalanche paths. Avalanches may propagate widely across terrain features, and break in surprising ways.

    The heavy snow and wind loading from the last week stressed a weak snowpack structure. At and above 6,000ft, avalanches could break on weak layers, including facets and facets/crust combinations 4-6 feet below the surface.  Targeted snowpack tests (deep tap and propagation saw tests) can help you identify the problematic layers. You may find two weak layers, the February 24th layer and the early February crust within a foot of eachother. Now that the snowpack has had some time to adjust, it's becoming difficult to trigger these avalanches near the Cascade crest. In the eastern portion of the zone, the structure is weaker and avalanches may be easier to trigger.

    (2/28/2024)

    In the neighboring East Central Zone. This remotely triggered avalanche in the Teanaway Drainage failed on facets over the Early February Crust. 

    5600ft, NEE aspectHS-ASr-R3-D2-O

    Photo: Mike Elges

Avalanche Discussion

Preliminary Report: An avalanche accident occurred on Friday, March 1 near Darland Mt in the Ahtanum Meadows area (East South zone). Two snowmobilers were involved in the slide. One rider was fully buried and killed. The avalanche occurred around 6600ft in a generally east-facing bowl. NWAC staff will visit the accident site on Saturday. Our deepest condolences to the family, friends, and community.

 

The most recent significant change was wind transported snow from southwest winds at mid and upper elevations on Saturday. Sun-exposed slopes saw enough sun on Friday and Saturday to form light surface crusts. On Friday, forecasters targeted sunny slopes in the Skyline area and found the early February crust not to be an issue for triggering avalanches at that location. However, a crust/weak layer, just below the February 24th interface showed a high potential for propagation, if triggered.  An observer reported natural avalanches on Jim Hill around 6,000-6,400ft, N, that occured earlier this week. While, it's unclear if these avalanches were running on storm interfaces or on deeper weak layers, facets above the early February crust were well-documented on this slope before storms began.

Since the 24th, the Stevens Pass area has received about 5" of water equivalent, and the snowpack gained 3-4 feet. The snowpack is slowly adjusting to all of the new weight. While we haven't been able to get to the most problematic, upper elevation slopes, profiles are generally showing a good bonding of the bulk of the snow that fell in the past week. There's still uncertainty ato upper elevations and in the eastern part of the zone. There have been numerous natural and triggered persistent slab avalanches in the neighboring East Central zone.

On Tuesday, multiple observers reported sudden planar test results with compression tests on small faceted grains above the early February Crust. These came in from Grace Lakes and Lanham Lake areas on northerly aspects. Two significant (D2+) natural avalanches were observed from the Camp Chutes off the south side of Rock Mountain on Tuesday. The timing of these is unknown but estimated between the 26-27th. The slides ran at least as low as the bottom of the track. A wide slab avalanche occurred on a SE aspect at 5,600ft in Highlands Bowl on Monday. That same day, control work at Stevens Pass Resort triggered avalanches that broke on the early February Crust.

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