Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Unsurvivable avalanches up to 10ft deep remain possible in the zone, as do wind slabs and wet loose avalanches. Saturday is not the day to step out into big features, but a day to be conservative and disciplined in your terrain choices. Avoid steep open slopes or even ones with sparse trees; have patience and let the snowpack settle out after significant snowfall and avalanches this past week. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    You'll find lots of recently wind-loaded slopes to be careful of. Slabs may be starting to become more difficult to trigger, but if you do trigger one it could be large or even step down to become a very deep and destructive avalanche. With wind slabs and the potential for deep slab avalanches, you should avoid large avalanche paths, especially at mid and upper elevations. Avoid wind-loaded, leeward slopes 35 degrees and steeper.  Below treeline, stick to wind-sheltered slopes and well-supported features. Watch for snow that slides easily on a recently buried crust on southerly slopes or on any convex, unsupported terrain feature.

    Example wind slab [Photo: Alpental Pro Patrol/Mac Miller]

  • Loose Wet

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

    With lots of fresh snow over a crust, warming temperatures and a late February sun, wet loose avalanches could begin running naturally on Saturday. If the sun is out where you are, expect these to happen on steep slopes that face toward the sun during the middle of the day. Moist, sticky snow and rollerballs are good indicators that the snow is capable of producing these. Time your travels to avoid steep south facing slopes in the middle of the day to avoid getting avalanched by a wet loose slide.

    Example loose wet avalanche.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3

    The uncertainty and unpredictability of deep persistent slab avalanches should determine where and how you travel. Avoid going into, or underneath open or sparsley treed terrain with large potential start zones above you. Avoid traveling on and beneath slopes 35 degrees and steeper. Slopes 5,000ft and higher and on east to south to southwest aspects are the most concern and have recently produced avalanches over 1,500ft wide and up to 10 feet deep. 

    A persistent weak layer involving facets on or within a crust that was buried in mid-January has plagued the snowpack with lingering instability for over a month and a half. While solar aspects appear to have been especially problematic, we know deep slabs have also run on shaded north and northwest aspects. Unfortunately, this problem isn't going away for a little while, and we shouldn't be surprised to hear about more of these monsters in the coming days. Saturday is not the day to step out into big terrain, but a day to let the snow settle. 

    (2/24/2021) A very deep crown (estimated at least 9 feet) on Tye Peak. This deep slab avalanche likely ran on February 22nd on facets above a crust from Mid-January. SE, 5150ft. Photo: Josh Hirshberg

Avalanche Discussion

A ski triggered avalanche occurred on Friday outside of the Stevens Pass Ski Area boundary. A skier was reportedly partially buried, and able to self extricate. They may have lost some ski gear in the slide. This avalanche (D2) was 18"-20" deep, and about 200' wide. It likely ran on the sun crust from the 24th. We don't have more details yet about this occurrence but are glad the person is ok. Another 22" of snow fell through Friday afternoon, following the massive storm earlier this week. The recent snow buried a sun crust on steep sunny slopes and weak snow may exist at this new/old snow interface on shaded aspects. Observers reported reactive wind slabs and professionals triggered slides up to D2.5 on Friday.

From the 20-23rd, the Schmidt Haus station picked up a whopping 6" of water equivalent! Numerous very large and destructive avalanches ran during a period of High to Extreme avalanche danger on the 21-23rd:

Observers reported D3 sized natural avalanches on a ESE aspect at 5,200ft near Skyline Lake (in the Moonlight area). These were at least 7ft deep, knocked down trees, and may have run on the 22nd. A similar avalanche was reported on a SW aspect, near 5,100ft on Nason Ridge, just west of Rock Mtn. In the Scenic area, guides reported size D3 natural avalanches running on the mid-January weak layer 3-10ft deep on W-N aspects. Natural avalanches ran on SE and SW aspects of the Tunnel Creek area to D2.5. WSDOT triggered a very large size D3 in one of the Old Faithful paths on a SW aspect below treeline. Observers reported natural avalanches to size D3 on a SE aspect of Lichtenberg Mtn as well as a D4 sized avalanche on a SE aspect of Rock Mountain in Schilling's creek. This avalanche broke many mature trees and deposited debris 40 feet high near Highway 2.  On Sunday, observers reported a very large D3.5 natural avalanche in the historic Wellington slide path on a SE aspect of Windy Moutain. A very large avalanche (likely skier triggered) ran on the mid-January weak layer, 5 feet below the surface, on a S aspect at 5,000ft, below Skyline Lake.

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