Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

It is going to be a frigid day at Snoqualmie Pass on Saturday. You’ll need to manage the cold wind and slabs created by it. The threat of very large avalanches should shape your travel plans to avoid big open slopes.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    The most likely location for you to trigger an avalanche on Saturday is on wind-effected slopes. Due to easterly winds, slabs may form on aspects you’re not used to or further down in the terrain as slopes cross-load. Visual clues such as fresh cornices, actively blowing snow, or textured surfaces can indicate where new slabs are forming. Additionally, there could be older slabs hidden beneath the surface. You’ll need to feel for changes in the density of the snow as you travel to identify them. Small test slopes and uptrack tests can help indicate how the snow reacts to your weight as a traveler.

    (1/11/2024)

    Small avalanches were easily triggered by skiers on Thursday in the Alpental Valley.

    Photo: Andy Harrington

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    Unfortunately, those small test slopes won’t give you any insight into the deeper and scarier layers in our snowpack. You’ll need to dig roughly 4 feet down to look at them. Lucky for you, we’ve done the digging already, and this problem is everywhere we’ve looked in recent weeks. The question mark is not about size or distribution but the sensitivity to triggering. Now that you know what’s below your feet and that it can produce unsurvivable avalanches, your best mitigation tool will be to stay off open steep slopes to minimize the possibility of you triggering one. 

    (1/10/2024)

    This very large avalanche released remotely from nearby explosive placement during avalanche control at Alpental. It is an indication that deeply buried weak layers could still be active. 

    Photo: Alpental Ski Patrol

Avalanche Discussion

Ambient air temperatures will once again feel arctic at Snoqualmie Pass. The uptick in easterly winds will be the kicker and create dangerously cold wind chills. Be prepared by bringing extra layers, hand warmers, face masks, and ensure those grip heaters work.

The Pass has received over 4 feet of snow over the last week, drastically changing the landscape. There are interstorm density changes, graupel, and the potential for dry loose. These are your standard PNW storm issues that you’ll need to continue to manage on Saturday. Remember that avalanches are easier to trigger on steep slopes over 35 degrees or where wind drifting has occurred. Multiple reports relayed that small wind slabs were easily triggered on Thursday.

What’s not standard is our concern for deeper layers in the snowpack. While you may find a few crusts in the upper snowpack, such as the 1/8, we are focused on the 12/30 and the Solstice Crusts. On Wednesday, Alpental Pro Patrol triggered very large avalanches with explosives that failed on these deeper layers. In the neighboring West South zone, multiple avalanches failed on them in the past week. We’re still gathering information about what may be needed to trigger one of these slides and where it’s more likely. We do know that if they fail, it will likely be unsurvivable. 

Saturday will be a good day to have a trustworthy buddy with you. Keep an eye on each other in the deep snow and for signs of frostbite.

Regioni coperte