Bollettino valanghe

Olympics

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

Forecast updated 7:30 AM due to heavier than anticipated snowfall overnight.

Dangerous conditions developed due to heavy snowfall rates overnight and isolated avalanches could be large. Navigate around all slopes 35 degrees and steeper with enough snow to slide. Avalanches may propagate more widely than you expect on weak snow interfaces or slick crusts.

Problemi valanghivi

  • Storm Slabs

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

    Upwards of a foot of snow fell at Hurricane Ridge in the last 24 hours, creating more widespread hazard than we initially expected. Given snowfall rates of 1-2" per hour in the early morning hours, expect touchy conditions when you head out, particularly in the morning hours. Slabs may release within the storm snow or may break down to weaker layers existing on NW-N-NE aspects prior to the storm. The storm snow may also sit atop a slick crust on some aspects or bare ground. Early season conditions increase your risk of trauma in any avalanche. Most avalanches will be small, but isolated avalanches in wind-loaded locations or on upper-elevation slopes could be large. Avoid all slopes steeper than 35 degrees at middle and upper elevations and on steep convex rollovers at lower elevations with enough snow to ride. If you observe signs of cracking, whumphing, or collapsing, dial back your terrain selection further.

     

    Example: Propagating cracks help you identify instability that can produce a storm slab avalanche.

    Photo: Sam Siemens-luthy

Avalanche Discussion

North aspects already have a shallow, but layered snowpack. You might find 6-18" of lower-density snow gradually forming a slab atop a crust-facet-crust combination. On N and NE aspects the upper crust is less than 1/2 inch thick, with a two inch layer of small facets above a stout crust. Avalanches could fail down to the stout crust with sufficient wind or snow loading, but this remains a low-likelihood scenario on Saturday. If you find evidence of shooting cracks or whumphs as you travel, this weak snowpack structure could be the culprit. The stout crust formed due to rain up to at least middle elevations before the late November dry spell. Shallow snowfall faceted during that late November drought that melted snow off of all but the NW-N-NE aspects.

As the new snow continues to stack up, remember that just a few days ago W-S-E aspects were bare ground. Dirt, rocks, downed trees, and stumps can catch you off guard while riding and may exacerbate a fall or any avalanche.

Regioni coperte