Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
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

Friday’s break in the weather should help the snowpack heal and make avalanches a bit harder to trigger. However, you might still cause a slide on very steep features, convex rolls, and wind-loaded pockets.

Problemi valanghivi

  • Storm Slabs

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

    The mild weather and near-constant trickle of snow this week generally allowed storm layers to heal and gain strength. However, fluctuating temperatures, periods of rain, and shifting winds left a few weaknesses to consider. The worst of these lingering layers are often crusts within and at the base of the recent snow. Hand pits and small slopes can help you find weaknesses in the upper snowpack. 

    Watch for trigger points like convex rollovers, the base of cliffs, unsupported slopes, and wind-drifted pillows where you could still trigger one of these slabs. Tree fences, cliffs, and creeks could turn one of these small storm slabs into a nasty ride.

    (1/22/2024)

    Human-triggered slab on a steep unsupported slope. 

    Photo: Andy Harrington

  • Loose Wet

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

    Slightly cooler temperatures and less rain should reduce the chance of wet loose slides. However, the lower elevation snowpack is a wet, punch mess. Unless there’s a new crust on the surface, you could push snow into an avalanche on very steep, rocky, and unsupported slopes. 

    These slides often seem easier to manage. Just don’t let one carry you over a cliff or into a creek.

    A natural wet loose avalanche in very steep rocky terrain. (1/23/2024) Photo: Kevin Trippe

Avalanche Discussion

We seem to be stuck in “Ground Hog Day” this week. Modest precipitation and warm temperatures pretty much sums it up. On Friday, we should see a break in the weather before we shift from mild and wet to hot and soaked. While this will allow for an overall decline in avalanche concerns, it won’t be enough to significantly drop the danger. 

This week, no day’s storm totals seem that impressive. However, middle and upper elevations added 12-18 inches of snow since 1/20. The rainline hovered near and just above Pass level. In a few instances, it spiked higher into the terrain. 

The upper snowpack consists of the recent storm snow and any thin crusts. At the 1/20 interface, a freezing rain crust often exists above 4500ft. Most of this middle snowpack remains cold, dry, and layered despite the mild weather. You can still see the 1/8, 12/30, and Solstice Crusts. Weak facets have been observed on or in each of these layers. For weeks, we discussed deep persistent issues within the zone. While we haven’t heard of avalanches on these layers recently, other forecast zones continue to be plagued by these lingering problems. 

The fact this snowpack is still generally cold, dry, and layered is a major concern as we head into a very warm and potentially wet period this weekend. Expect avalanche danger to rise rapidly Friday night into Saturday. Given the uncertainty and potential for big natural avalanches, this might not be the time for winter snow camping.

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