Lawinenlagebericht

West Slopes North

Northwest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Sun
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
Open full map
Veraltet — dieser Lagebericht ist 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Cooler weather is finally approaching but glide avalanches could linger for another day or two. Search for gaping glide cracks, or snow swaths suspended on exposed rock slabs on steep slopes and avoid traveling beneath these unique features. Snow conditions will vary widely, with punchy or variable crusts, and upper elevations should get a few inches of snow, possibly enough for you to be able to trigger an avalanche in wind drifted areas. 

Lawinenprobleme

  • Glide Cracks

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Glide avalanches tend to remain a problem even as temperatures begin to cool down. Although likelihood of one of these events occurring is on the lower end of the scale, you just never know if or when one is going to break, so your best course of action is to avoid traveling beneath glide cracks right now. If a glide crack does fail above you, consequences will be high and the resulting avalanche could possibly be unsurvivable. 

    The same goes for other prolonged warm, wet weather snow problems. Any slabs of snow sitting over exposed rock features are suspect, as are cornices or any other locations where snow chunks may break free and slide downslope. You might just have a big chunk of snow fall on you, or there's a small chance that one of those snow chunks could trigger an avalanche on any steep slope it falls on. 

    An old photo of glide avalanches on the south side of Mt Herman in the Baker backcountry. Avalanches like this could happen on Saturday. 

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Freezing levels are dropping to 4000ft, and rain is expected to rapidly transition to snow at upper, then middle elevations. Search for developing wind slabs, as winds will increase from moderate to strong as the day progreses.  You'll likely see actively blowing snow. Identify where it lands. Search for thicker-feeling deposits beneath you. Drifts oftentimes build on rollovers, around rocky features and on the sides of gullies. Identify these suspect locations, and if you notice any wind slab development in these areas, steer around them on slopes steeper than 35°. 

    New snowfall amounts will probably be less than 4 inches. However, we received a few inches of snow at upper elevations on Thursday night that could increase the size of slabs and subsequent avalanches. This means wind drifts could be well over a foot deep.

    We're unsure how well the snow will be bonded to the underlying crust from Tuesday's rain event, but we expect any new snow will probably stick to the crust. Additionally, Saturday's incoming snow will likely fall right-side-up, due to falling temperatures as it's snowing. This leaves us with wind drifted locations as the most likely places you'll trigger an avalanche in the new snow.

    Example photo of a small wind slab, similar to one you might be able to trigger on Saturday. 

Avalanche Discussion

Most snow surfaces are irregular, and you can expect to find rain runnels and varying levels of punchy or crusty snow at all elevations. Expect challenging travel conditions if you get out. With the dropping freezing level, the wet crusts will begin to freeze up and get harder as the day progresses, especially if you're making it to the mid or upper elevation bands. New snow up higher will be a welcome change. Meanwhile, in the lower elevation band if you can't find any deep, continuous swaths of snow avalanche activity it probably minimal. 

Tuesday night's 3+ inches of rain left us with moist snow down to the 12/7 crust, which is 2-4ft below the surface. Beneath the 12/7 crust the snowpack was already moist from the previous rain that fell in most areas. There may be some spots near the top of our upper elevation band where dry snow exists somewhere in the snowpack. A natural avalanche cycle occurred Tuesday night with widespready avalanche activity observed in the Baker backcountry, including Bagley Basin and the Arm, up to D2.5. Peak instability quickly passed and avalanches are few and far between now, but the danger is not quite low. 

 If you make it into the backcountry this weekend, please share with us what you find so that we can write better avalanche forecasts for you and the community. You can submit observations HERE. 

Abgedeckte Regionen