Bulletin d’avalanche

Snoqualmie Pass

Northwest Avalanche Center
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Danger d’avalanche

Tue
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
4 · Fort
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Points saillants

Heavy precipitation, strong winds, and warming temperatures will create very dangerous avalanche conditions Monday at the Pass. There’s the potential for several rounds of natural slides throughout the day. Avoid any area where avalanches can start, run, or stop.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1.5–2.5

    Expect natural avalanches to occur during periods of heavy snowfall, intense blowing snow, and warming temperatures. As the storm ebbs and flows throughout the day, this could result in a few natural avalanche cycles. While we aren’t typically expecting huge slides, many of these avalanches could easily grow large enough to bury and kill you. 

    We think most of these storm slabs will release within the new snow. However, a few isolated avalanches could fail on slightly older and deeper layers in the upper snowpack. This may result in very large slides in a couple of locations.

    (1/13/2023)

    Example: You could see natural avalanches like this on Monday around the Snoqualmie Zone. 

    Photo: Trevor Kostanich

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–2

    Near and below the rain-snow line you’ll encounter natural wet avalanches. This could include deep glides and shallow wet slabs. These slides could run in any steep open terrain, even below treeline.  In some cases, dry avalanches from higher up the mountain may entrain wet snow as they descend. 

    If you enter an opening in the forest, consider if there is steeper terrain above you. Avoid traveling on or below steep open slopes. 

    While wet avalanches can seem slow and easier to manage, if one of these flowing rivers of concrete catches you, it won’t let go until it comes to rest. They could easily bury you or push you into a creek, tree, or rock.

    Example: You could see natural wet avalanches like this at mid and lower elevaitons.  W Face of Kendall. W, 5600ft, WS-N-D2.5-R2-U, likely from the 1/12-13 cycle. Photo: Dallas Glass

Avalanche Discussion

While this isn’t the craziest storm, it is still very strong and comes with four compelling variables: heavy precipitation rates, significant snow accumulations, very strong winds, and rising snow levels. With storms like this, expect dynamic conditions throughout the day. You could see the snow respond differently from one hour to the next. Don’t get complacent if signs of unstable snow aren’t immediately visible. These classic red flags all point toward unstable snow and natural avalanches. 

There is some good news. Observations from the past several days indicate the upper snowpack is strong and should generally handle the new snow well. That means, while we can still find the 2/17 and 2/13 interfaces, we aren’t expecting widespread avalanches on these older layers. That doesn’t mean they won’t happen, but those events should be more isolated. 

Observations from Sunday at the Pass indicate a few very small slabs failed at the 2/17 interface. This seems similar to Saturday and may correspond to isolated pockets of buried surface hoar found by the NWAC team on Friday near Stampede Pass. At lower elevations, several small loose wet slides were reported over the past few days.

Régions couvertes