Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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In sintesi

You may be able to trigger pockets of recent storm snow near ridgelines or in steep rocky terrain on Sunday. Avalanche hazard should increase as you ascend in elevation toward where the snow is drier and more wind-blown.

Problemi valanghivi

  • Wind Slabs

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    1

    Sunday will be the third day in a row that waves of precipitation and wind impact Snoqualmie Pass. As we slowly increase the storm snow depth and the wind blows it around, keep Wind Slab avalanches on your mind. The most likely location for you to trigger an avalanche will be at middle and upper elevations on leeward slopes,  steep terrain features over 35 degrees, or near rocky terrain such as cliffs and confined gullies. Look for freshly built cornices, actively blowing snow, or textured snow surfaces to help you identify if these features possibly contain Wind Slabs. Using test slopes or uptrack tests can help you identify if the recent snow has slab potential and how it may react to your weight.

    (3/20/2021) This slab avalanche had a 6" crown and ran almost 1000 vertical feet. It was intentionally triggered by a ski cut on Saturday (3/20) in a rocky, confined gully. [N 5100']

Avalanche Discussion

Another few inches of snow fell at Snoqualmie Pass on Saturday, bringing the storm total to just over 6 inches for many areas in the zone. Overall, snow totals haven’t been too impressive, but there is just enough snow out there to create small avalanches, particularly in more extreme terrain like rocky chutes. Observations from Saturday indicate that the wind was able to actively transport snow near ridgelines, creating some shallow Wind Slabs. At middle elevations, observations revealed that slight daytime warming helped recent storm snow to “slab up” a bit in some parts of the zone, resulting in human-triggered slab avalanches that may be better characterized as Storm Slabs. Regardless of what name you give these avalanche problems, with a few more inches and a bit more wind on the way, we should continue to deal with similar slabs on Sunday.  You could also encounter some freshly built cornices near ridgelines that could be sensitive, requiring you to give them a wide berth.

Beneath the recent storm snow, you will find a variety of surfaces, including breakable crust, firm melt-freeze crust, wind-stiffened snow, moist snow, and possibly faceted snow. These surfaces vary based largely on aspect or elevation, so take the time to investigate the bonding and potential for avalanches to run far and fast on a crust in the location you are in. If you are at lower elevations, you may find that the snow is wetter and heavier, having the make-up for Wet Loose avalanches. Although you could see some rollerballs or push snow on some features, we don’t believe there is enough recent snow to really drive a hazard at lower elevations at this time. 

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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