Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Human triggered avalanches on wind loaded slopes at higher elevations are possible.  Identify wind loaded features by feeling for stiffer snow or seeing textured surfaces, and avoid these areas on slopes steeper than 35 degrees.   The sun shining on Monday will possibly produce wet loose avalanches on steep slopes on the southern half of the compass, so avoid those slopes and traveling beneath them if the snow moistens and you notice rollerballs beginning to come down. 

Avalanche problems

  • Wind Slabs

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

    On Saturday afternoon we received reports of two separate avalanches on the north side of Table Mountain (~4500ft). A small human triggered avalanche occurred in 5 Minute Trees, a slope which already had several tracks on it from the same day. It caught and carried the backcountry rider, burying them to their knees. We’re glad to hear that they got out without injuries. Nearby, a large (size D2+) natural avalanche was witnessed in Blueberry Chutes, and it is suspected that a cornice may have triggered it. On Sunday there was another report of a small skier triggered wind slab avalanche in the Bagley Lakes area.  Avalanches are most likely to fail on new snow instabilities, but these now may be a few feet deep, and big enough to bury, injure, or kill you. 

    Wind slabs developed in the 2+ feet of new snow over the last 3 days on leeward slopes near ridgelines, in gullies and around features. Most of the wind came from the south, so you will find more slab development on the northerly half of the compass. Expect wind slabs to remain reactive to human triggers for at least one more day once the storm clears out Sunday night. Slabs could fail within the new snow interfaces (a few were reported as 4" deep), or beneath the new layers on a crust  that formed on all aspects up to about 6000ft on March 4.  Feel for changing snow conditions as you are traveling. Notice when the snow becomes more firm, and when you see ripples or a textured surface indicating wind loading. Avoid slopes steeper than 35 degrees where there is wind affected snow. Exercise caution around cornices, as they've continued to grow and could easily fall.  Stay far back from their edges, and do not travel on slopes beneath these large features. 

    This small wind slab avalanche was triggered on Sunday in the Bagley Lakes area.

  • Loose Wet

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

    Uncertainty exists around the size and likelihood of wet loose avalanches on Monday.  You will probably at least see rollerballs coming down, but they may become more reactive and run naturally up to destructive size 2. One of the largest factors affecting the size and number of avalanches is the abundance of low density snow on the southerly half of the compass, as that was the direction most of the wind came from over the last 3 days. If dry, low density snow exists on steep exposed sunny slopes, expect large avalanches to run as the sun dampens the snow.  

    Feel for the sun moistening the snow surface. When this happens, retreat to shady slopes, especially in areas where low density snow is on south facing slopes near you, or if you start to see rollerballs. The March sun has rapidly become so much stronger than just a few weeks ago, so take that into account when planning your adventure.  

     

    Wet loose avalanches could run naturally in the new snow from steep sunny slopes on Monday. Photo: Zach McGill

Avalanche Discussion

About 3.5" of water (31" snow) fell at the Heather Meadows weather station since Thursday. Much more snow fell at higher elevations. Several wind slab avalanches were reported over the last few days, one of which involved a person.  The storm died down Sunday night, and Monday being the first bluebird day in a while, continue to exercise caution as the storm just finished. 

There are layers of concern in our snowpack buried over 10 feet deep, although most  recent avalanches failed on shallower layers in this zone. Recent loading with the new snow was a good test to see if it might wake the dormant layer.  We last saw avalanches on it over a week ago, when there was a widespread natural avalanche cycle that resulted in many very large avalanches (D3+), some hitting Highway 20 just outside Newhalem. Several very large avalanches were reported further south in the zone. Our concern, a mid January deep persistent layer is 200 - 300+cm deep in most areas and is hard for a human to trigger. However, a huge sudden load such as a cornice fall or a shallower wind slab avalanche might trigger an avalanche on that layer. 

Snow and avalanche conditions are variable in the West North zone and throughout the Cascades right now. In general, recent storm snow is stabilizing quickly, but very large natural avalanches along the border of the Stevens and West Central zones continue to keep these old and deep weak layers on our minds in this zone as well. Read the West Central or Stevens Pass Forecasts to learn more about it. 

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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