Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

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

You’re most likely to trigger an avalanche in wind drifted snow mid and upper elevations. Because of the recent strong winds that frequently shifted directions, you may find these slabs on a variety of aspects and features including well below the ridgelines. Steer around firm smooth pillow-like drifts when you travel in steep terrain.

Problemi valanghivi

  • Wind Slabs

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

    Wind slabs should continue to grow Saturday night and into Sunday morning as more continues to fall. The winds during this storm have been strong and gusty, and changed directions several times. As a result, the loading pattern may be rather sporadic and hard to predict. You could see firm slabs on a variety of features even well below ridgelines and further down in gullies and chutes. Be on the lookout for textured surfaces and firmer drifts to help anticipate where the potential avalanches could exist. Steer around pillow-like drifts, especially in high consequence terrain where even one of these smaller avalanches could harm you.

    (3/9/2022)

    Example: Firm smooth pillow-like drifts and sharp wind lips during at previous wind event. These features can be seen well below the ridge.

    Photo: Andy Harrington

Avalanche Discussion

On Saturday, the upper elevations picked up 4-5” of snow. Unfortunately, sun breaks allowed the lower terrain to warm significantly. So, despite the influx of colder air, rain continued to fall at pass level. That should change Saturday night and snow showers will continue to slowly add to the storm totals. A Puget Sound Convergence Zone is currently aimed at the central Cascades. This feature could shift south and bring periods of heavier precipitation to the zone. If this happened more snow could accumulate than anticipated allowing for possibly more dangerous avalanche conditions. Fortunately, outside of wind-affected areas, the new snow seems to be bonding well to the old relatively warm surface. 

While we expect any avalanche activity to only involve the new storm snow, we do have some uncertainty in the upper snowpack. A layer of weak facets buried on March 8 has been well documented over the past week. You may find them by looking just above the very prominent and stout Early March Crust (likely down  2-3 ft/60-90cm) on NW-NE aspects. Recent observations by several avalanche professionals found these weak grains were moist and gaining strength. However, all observations were below 5000 ft. That may not be the case at higher elevations. The only known in this zone occurred on Friday afternoon when a tree bomb triggered a deep, but small pocket (2 ft deep, 20 ft wide) on a N-facing slope at 4400 ft above the Cache Coulior on Chair Peak. This weird avalanche definitely has us scratching our heads. Take this layer into account if you plan to travel onto high consequence or unsupported alpine terrain. 

At lower elevations, there’s just not enough new snow to pose much of a risk. However, you could encounter challenging travel with breakable crust, firm rough surfaces, open creeks, and even frozen piles of avalanche debris.

Regioni coperte