Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
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Out of date — this forecast expired 6 years ago.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

Windy conditions and some new snow should be enough to create some fresh Wind Slabs on Friday at Snoqualmie Pass. The snowpack still needs time to heal and adding any amount of stress could push slopes past their tipping point. So make conservative terrain choices and know that even small avalanches may grow large and deadly.

Avalanche problems

  • Wind Slabs

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

    Winds on Thursday night will be strong enough to transport snow to create fresh Wind Slabs at middle and upper elevations. As Friday morning approaches, winds should downtrend, but may still be strong enough to continue to wind-load features as new snow starts to fall. A switch in wind direction during the forecast period means that you will have to be aware of wind-affected snow on all aspects and to keep your eyes open for unusual loading patterns. Take a look for actively blowing snow, textured snow surfaces, fresh cornices, or smooth pillow-like piles of snow to help identify where Wind Slabs may have developed. Pay particular attention to the sides of gullies, the base of cliffs, and convex rollovers where wind-deposited snow often is deposited. Triggering even a small Wind Slab could have significant consequences by then triggering larger Storm Slabs in the recent storm snow. Using small test slopes can help you test the reactivity of recent Wind Slabs, but as a general rule, you should avoid any suspected wind-loaded features greater than 35 degrees.

    (12/22/2020) Wind Slabs such as this are a hazard on their own. On Friday, a similar slide could go on to trigger larger and deeper slabs, becoming more consequential.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    In case you haven’t heard, we just got a ton of snow at the pass which resulted in a lot of avalanches. We continue to receive reports of recent large avalanches, and the possibility still remains of you triggering one of these slides on Friday. With the aid of fresh Wind Slabs and a bit of new snow, some slopes could finally reach their tipping point. With so much recent snow out there, any triggered avalanche has the capability of traveling long distances and growing large enough to bury or kill you. Hand pits and test slopes will only give you enough information to determine what is happening near the surface of the snowpack. To get the full picture, you will need to dig down to the 1/1 interface. Unsupported slopes, convex rollovers, and wind-loaded terrain are areas where starting an avalanche is more likely and should be avoided.

    (1/6/2021) Slab activity has not been difficult to find over the past week. Continue to give the snowpack time to heal before stepping into aggressive terrain.

Avalanche Discussion

Friday should be another day to continue being patient as we work our way out of a major storm cycle and give the snowpack time to heal. Although the danger has dropped to Moderate, the travel advice, size, and distribution all more closely mirror Considerable danger levels. You need to continue to evaluate the snowpack carefully, use cautious route-finding, and conservative decision making out there. Don’t be surprised to hear about some very large (D3) avalanches occurring over the next few days. Multiple avalanches reported during this cycle have traveled to valley bottoms and filled in terrain features where people often travel and there are a lot of question marks about conditions at the highest elevations. You may feel like things are “locked-in” or "feeling good" under your feet as you travel, but take a minute to dig and see for yourself what lurks beneath the surface of the snow. Observations continue to point to instabilities in the upper snowpack, mostly confined to layers above the 1/1 crust. More potential weak points will be created Thursday night and Friday morning with this quick bout of weather. As noted above, any triggered avalanche has the potential to entrain snow or step down to grow large and destructive, so think hard about the consequences before stepping into avalanche-prone terrain.

Other dangerous conditions may exist on Friday as you travel in the mountains. Creeks are running high at lower elevations, large amounts of snow and branches are falling from trees, and the deep snow creates a hazard due to tree wells and deep snow immersion. Find out more information about deep snow safety HERE.

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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