Lawinenlagebericht

Stevens Pass

Northwest Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

Unpredictable avalanches up to 10ft deep remain possible in the zone, as do wind slabs, storm slabs and cornices. Deep slab avalanches have been releasing naturally on east to south to southwest aspects near treeline, and more could occur on Sunday. Avoid going into, or underneath steep open terrain, giving the snowpack more time to stabilize after significant and destructive avalanche events over the past couple of days.

Lawinenprobleme

  • Deep Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    3–4

    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 of D4 in size, 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 south and east-facing aspects appear to have been especially problematic, we know deep slabs have also run on 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 next few days. Continue to let the whopping amount of new snow settle, and tread carefully around these sleeping dragons on Sunday.

    Another deep persistent slab avalanche ran naturally at around 10:30pm on February 26th in a path known as West Camp off Rock Mountain above Highway 2 east of Stevens Pass. Southeast to Southwest aspects with the crown running from around 6,200ft to 5,400ft.

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2

    Fresh snow and strong winds will again create reactive wind slabs. Even outside of wind affected areas, you could trigger avalanches in the recent storm snow. A sun crust from the middle of the week was responsible for a close call with a skier triggered avalanche. If trigger an avalanche in the upper foot or two of snow, it could be large or even step down to become a very deep and destructive avalanche. With wind slabs, storm 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. 

    (2/26/2021) This avalanche was about 20" deep x 200ft wide, and ran on the suncrust from February 24th. It caught a skier who was then partially buried, and lost some ski gear. Southeast aspect at 5150ft in the Polaris Boundary Glade.

Avalanche Discussion

A massive avalanche ran naturally out of a path on Rock Mountain called West Camp on Friday night at around 10:30pm. The powder cloud took out power lines and dusted Highway 2 with tree debris. This avalanche started on Southeast to southwest aspects at around 6,200ft and took out substantial amount of forested trim line around the runout zone (see photos below). Size has not been calculated yet, but it is at least a D4. A partial burial occurred on Friday just outside of the Stevens Pass Ski Area boundary. This avalanche (D2) was 18"-20" deep, about 200' wide, and ran on a steep southeast aspect at 5,150ft. We are glad the person is ok. On Saturday Stevens Pass Ski Patrol inspected this avalanche and found that it ran on preserved stellar crystals over the sun crust from the 24th, and snowpack tests continued to indicate the potential to create avalanches. Another 22" of snow fell through Friday afternoon, following the massive storm earlier this week. 

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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