Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

Wednesday will be the warmest day of the week so far. Wet avalanches will be possible once the sunshine and warm temperatures are able to overcome breezy conditions and soften the snow surface on sunny slopes. When this happens, consider heading toward shadier aspects.

Problemi valanghivi

  • Loose Wet

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

    Despite cool winds trying to keep the Wet Loose avalanches at bay, we expect that snow surfaces will soften in the rising temperatures and spring sunshine on Wednesday. On sunny slopes, take a moment to step out of your mode of travel and check how deeply you are sinking into the snow. If you find that you are sinking past your ankle, the warm weather has overcome the cool breeze and you should start to think about wet avalanches. Other visual clues like fresh rollerballs or recent avalanches with fan-shaped debris can help you determine that the snow surface has destabilized and it is time to head toward shady slopes to mitigate your hazard. Wet avalanches are complex and often intermingled; wet loose, wet slab, cornice, or glides could all occur on sunny slopes, entrain significant snow, and possibly grow large while traveling long distances toward lower elevations. Choose safe travel routes and be aware of your overhead hazard at all times. 

    (4/11/2021) Wet Loose avalanches were observed in the Alpental Valley on Sunday 4/11 as sunshine destabilized recent storm snow and it started to shed from trees and rocks around noon. Skiers for scale.

  • Wind Slabs

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

    It's been a bit gusty at the pass recently, and those winds should continue Tuesday night and into the day on Wednesday. Plenty of cold dry snow still exists on shady slopes that don’t see direct sunshine, and this snow may have been blown around to create some shallow Wind Slabs. Take a look for these slabs as you ascend in elevation near rocky features such as the sides of gullies or the base of cliffs, or on leeward slopes near ridgelines. Due to winds coming predominantly from the East, slabs may have formed in areas you are not typically used to finding them, or cross-loaded features. Keep a keen eye out for textured snow surfaces or fresh drifts behind objects such as trees and rocks to help you identify wind-loaded features to steer around.

    (4/8/2021) One of two shallow wind slab avalanches triggered by skiers near the Bryant Peak Couloir on 4/8. The other avalanche was triggered by a different party a stone's throw away. [NW 4800'; Photo: Bennett Melville]

Avalanche Discussion

Observations at the pass continue to be limited, but a battle between breezy conditions and temperatures creeping ever higher in the springtime sun ensued on Tuesday. Expect similar conditions to develop on Wednesday, with even warmer temperatures and winds set to downtrend in the afternoon. 

Many aspects have been receiving direct sunshine and should be going through a melt-freeze cycle due to cool nights and warm sunny days, creating a firm surface crust with cold snow below it. Tuesday night may be the last night this week for us to get a strong overnight freeze, after which conditions could potentially become much more unstable as we head toward the weekend. On shady slopes, cold dry snow should still exist on the surface, creating an aspect-dependent snowpack. As the snow surface softens throughout the day on sunny slopes, expect a continuation of the springtime shedding cycle that started on Sunday and is expected to produce wet avalanches, snow falling off trees or rocks, glide avalanches, and cornice collapses. On the shady side of the dial, keep an eye on new and recent layers in the snowpack that are confirmed to have weak snow and produced multiple human-triggered avalanches over the weekend. They could still produce dry avalanches on Wednesday.

Barring some unforeseen development, this is my last avalanche forecast for the season. I want to take a minute to say thanks to everyone for a great year. To all who submitted public observations, I really appreciate it, thank you. I know it may seem like we are always pleading with you to submit more, but they genuinely do help us as forecasters and make the product better. I encourage you to continue to submit them throughout the spring to keep us and the community in touch with what is going on with the springtime melt-out. Just because we are off the clock does not mean that we are checked out. Have a safe and fun offseason and I’ll see you next year!

Daily avalanche forecasts will end on Sunday, April 18th.

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.

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