Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Sunshine and rising temperatures will try their best to cause the snowpack to become wet and unstable. As the day warms up, you may see snow start to fall down. Choose routes that help limit the amount of time you spend below steep and rocky slopes which could produce natural avalanches.

Problemi valanghivi

  • Loose Wet

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

    A frozen snow surface in the morning will need time to thaw before you start to worry about loose wet avalanches. The thinner/weaker the freeze, the faster the surface snow may become unstable. Your boot can serve as the simplest tool for monitoring changes at the surface. When you begin to sink into the snow near or past your ankle, it’s time to find somewhere else to travel. Expect snow surfaces to soften in the morning on east-facing slopes before spreading to other aspects and higher elevations as the day continues to warm. When you find wet, sticky, or punchy surface snow, seek out more frozen or lower angled terrain. Even though these slides may start out small, with a weak and generally wet upper snowpack, they could entrain significant snow and grow large.

  • Glide Cracks

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

    Several large glide/shed avalanches occurred this weekend at Snoqualmie Pass. What struck NWAC staff during our field day Sunday was how many slopes had not yet released. As temperatures again soar above freezing, you may see large blocks of snow shedding from cliffs or glide avalanches failing on smooth steep slopes. These types of avalanches are inherently challenging to predict. The only real tool in our toolbelt is avoidance. Choose routes that help you limit the amount of time you spend below steep rocky faces and slopes where you see crevasse-like glide cracks. Snow may fall from this terrain without warning, grow into large destructive avalanches, and even cross common travel routes.

    (4/4/2021) Multiple Glide avalanches as large as D3 descended on Saturday in the Alpental Valley. The largest slide on the right crossed a very popular travel route

Avalanche Discussion

This is a tricky forecast. Much of it hinges on the overnight freeze and Tuesday’s sky cover. A poor freeze and full sunshine could result in more dangerous conditions than anticipated. If you begin to see large natural avalanches, the snowpack passed the tipping point, and it’s time to dial it back. This may be a good day to choose more conservative terrain than the Moderate danger might normally cause you to select. Make sure your return route to the trailhead allows you the ability to adapt to the dynamic spring conditions. 

One thing’s for sure, you’ll experience the lowest hazard of the day in the morning. As the day warms up, how quickly the danger increases will depend significantly on the overnight freeze. On E-S-W aspects, recent warm and sunny weather caused much of the upper snowpack to begin to undergo several melt-freeze cycles. However, deeper in the snowpack, and on other aspects, a cold and dry snowpack still exists. Despite the spring-like weather, the snow has not fully made this transition. As it does so, you may see snow shed from rocks and cornices fall down. Pay lots of attention to your overhead hazards and minimize any time you spend on slopes below. 

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