Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

Rapidly warming temperatures and strong sun will quickly destabilize the snowpack. Expect wet loose avalanches to be easily triggered as the daytime warms, and some of these could grow large. Avoid steep slopes as soon as signs of warming snow surfaces become apparent, such as rollerballs, and wet, heavy or punchy snow.

Problemi valanghivi

  • Loose Wet

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

    Strong sunshine and rapidly warming temperatures will create unstable snow and wet loose avalanches on Wednesday. Look for indicators of wet activity such as moist surface snow, rollerballs, and other small fan-shaped avalanches as the day progresses. Loose wet slides could grow large and dangerous near the pass where around 1ft of snow may be found over the recently buried melt-freeze crust. While loose avalanches are predictable, they could be especially dangerous on sustained steep slopes and near terrain traps such as cliffs and strainers. 

    Above treeline, activity should be limited to slopes in direct sun. Directly north-facing slopes at upper elevations may stay cooler, although at lower elevations, temperatures should be warm enough that we could see wet slides occur even on shaded slopes. 

    Example wet loose avalanche in the Mt Baker Backcountry. Photo: Zack McGill

Avalanche Discussion

Temperatures are forecast to be the warmest of the week on Wednesday, and mostly sunny skies will quickly warm snow surfaces. Cool temperatures in the morning will quickly change, and expect rising avalanche danger as the daytime warms, and as sun hits each slope aspect. Considerable is the highest level or danger that we expect the day to reach. On Tuesday, the warming trend continued, and observers noted small natural loose wet avalanches in west facing terrain such as Wenatchee Bowl. A winter storm delivered up to 15" of snow accumulating on Monday morning. West winds were gusty and strong. Stevens Pass Ski Patrol and DOT highway forecasters trigger avalanches in the new snow on Monday. Most of the avalanches were small and were on steep, wind-loaded slopes. One avalanche, in the Old Faithful highway path, was big enough to bury a person.  On wind-sheltered slopes up to 35, the snow was generally well-bonded and difficult to trigger. Despite the strong to extreme winds, many slopes were surprisingly unaffected by the wind. In other areas, observers noted drifts and slabs in low elevation open terrain where the wind was channeled by long valleys and passes.

On Sunday, Josh Hirshberg dug a profile on SE, 5,400ft almost 7 feet down to the January 24th facets. While the grains have rounded quite a bit, the layer is still notably softer than the adjacent layers. The layer of facets on a crust from Mid-January was responsible for the February avalanche cycles. The last known deep slab avalanche in this zone was on March 1. Major warming events later in spring and summer could trigger further rounds of avalanches on this layer. 

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.

Regioni coperte