Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

East wind has created touchy new windslabs on exposed slopes. The chances of triggering a deep, persistent slab avalanche are less than earlier this week, but they are still possible. The only way to be sure to not trigger a deep avalanche will be to stay off of steep open slopes where over 3ft of snow rests over facets on a crust.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    On Thursday, easterly winds began to form reactive, shallow slabs. You are likely to find these slabs in areas where wind funnels through, such as near the pass and areas exposed to the highway corridor. Feel for slightly thicker snow, and look for signs of active wind transport such as small plumes near ridgelines. If you find long shooting cracks in drifted snow, stay off of steep slopes nearby. Any avalanche in the new snow could step down to deeper weaker layers and result in a very large and deadly avalanche above 4,000ft. Consider the terrain you're connected to and avoid steep, open wind loaded slopes. Outside of wind-affected areas, you could trigger small sluffs. 

    (2/11/2021) Long shooting cracks were observed in freshly drifted snow in wind exposed terrain on Thursday.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3

    Quiet weather and time have helped to decrease your chances of triggering one of these, but a large amount of uncertainty remains. In most places above 4,000ft, the weak structure can be found.  You probably won't get any warning signs such as shooting cracks or whumphs. If you do get a whumph on a steep slope, it could be your last. Wise backcountry travelers continue to stay well away from steep open slopes near and above treeline because of this. Put a large buffer of terrain between where you travel and large avalanche paths, especially wind loaded areas. Travel like the terrain could avalanche big, and make sure to stop and regroup only in truly safe areas.

    About 3-5 feet below the surface, you can find a softer layer of weak faceted snow above or around a crust that formed in mid-January. Sudden and propagating snowpack tests on this layer can indicate the potential for an avalanche. While these avalanches may be less likely below treeline, this weak structure can be found in open terrain above 4,000ft, so we can't rule it out.

    (2/7/2021) A two party involvement occurred on February 7th. Skiers triggered a very large (D3) avalanche which partially buried 2 people. The avalanche released on a NE aspect at 6,100ft on Jim Hill in the Stevens Pass zone.

Avalanche Discussion

We are in the middle of a prolonged period of dangerous conditions with deep persistent slab avalanches throughout many NWAC zones. On Monday February, 8th, two motorized snow bike riders were caught and buried by a very large avalanche in the East Central Zone (See the short video in the media gallery below). 

On Thursday observers in the zone reported sustained, moderate wind transport of snow. Long shooting cracks in freshly wind drifted snow caused some professionals to take a step back in their terrain choice. Only light accumulations are expected through Friday afternoon, but cold temps and wind are the driving factors for this fresh wind slab instability. A widespread crop of large surface hoar and surface facets were observed before this round of snowfall over the past few days. This will be worth keeping on your radar as we move into the weekend and add more new snow over the top.

Last weekends storm added around 4ft of settled snow to the pack. Reports of natural and human-triggered slides have continued to come in: On Wednesday, a very recent, natural avalanche occurred at Snoqualmie Pass on a Northeast aspect at 5,000ft (see photo below). A two party D3 avalanche partially buried two people on Jim Hill on Sunday. On Monday, Highlands Bowl ran (Southeast at 5,600ft). This slope was also the site of a widely propagating avalanche on Friday and skier triggered avalanches on January 27th.  A very large natural D3 avalanche likely ran on the night of the 6th on a NW aspect of Jim Hill into the Lanham Creek drainage. There were also very large avalanches observed on Upper Nason Ridge (photo below), Tunnel Creek (photo below), NE slopes 5,400ft above Lake Susan Jane, and NE slopes 5,400ft above Swimming Deer Lake.  

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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