Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

You may trigger shallow pockets of wind-affected snow near exposed ridges or in rocky complex terrain. Look for pillow-like drifts that you want to avoid before committing to higher consequence slopes.

Problemi valanghivi

  • Wind Slabs

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

    The most likely place to trigger a slab avalanche Tuesday is in wind-affect terrain. Most of these wind-loaded pockets should be generally soft and easy to spot. Look for pillow-like slabs below cornices, along the base of cliffs, or in rocky areas. Given the recent wind direction (E-S), some of these avalanches may occur on some unusual aspects. Even though most of these slabs should be fairly shallow and easy to manage, some of them could be large enough (D1.5) to take you for a nasty ride. Think about the consequences of terrain below you before venturing onto any wind-affected feature. 

    A few larger (D2) hard wind slabs may still linger at mid and upper elevations from Saturday’s (3/4) strong SE wind event. Be leery of firm hollow sounding snow, especially in convex or unsupported terrain. Hard slabs are difficult to assess and often break above you with little warning.

    (3/6/2023) Reverse loading was evident along ridgelines. You may see wind slabs on some unusual aspects. Photo: Dallas Glass

Avalanche Discussion

While passing snow showers could bring a few inches of snow to the Pass by Tuesday afternoon, they shouldn’t affect the avalanche danger. Instead, they’ll only add to the storm totals since 2/25. Over the past 9 days, more than 4 ft of snow has fallen with cold temperatures. Not surprisingly, travelers routinely report deep conditions with a generally right-side-up snowpack. 

Most avalanche activity this past week has been limited to a few small (D1) natural and human-triggered wind slabs and loose dry avalanches. However, two deeper slides have been reported and definitely have our attention. On Monday an avalanche professional found a large (D2.5) deep (~3ft/1m) avalanche in the Chair Peak Lake Basin (E, 5600ft) We don’t know exactly when this slide occurred. The depth is rather similar to an avalanche from Friday (3/3) where an intentionally triggered wind slab stepped down to an older snow layer. In both cases, we suspect the 2/25 crust. Weak snow (facets and surface hoar) has occasionally been observed at this older interface. While these slides still appear isolated, take them into account before stepping into bigger terrain. One of these deeper slides seems most likely in shaded, sheltered areas with a larger trigger (cornice, avalanche, or snowmobile). 

While temperatures are cold, it's starting to feel a bit more like springtime. So, if the sun comes out for a longer period, expect the snow to shed from trees and rocks. This could trigger small loose avalanches on the slopes below. A thin crust formed by the Sun on 3/5 and increasing afternoon clouds should help limit any loose wet issues. However, if you see new rollerballs or teardrop shaped debris, expect avalanches on similar terrain.

Regioni coperte