Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

Udate 7:45- Downgraded from High danger due to less new snow than anticipated. An incoming storm will create dangerous conditions with moderate to heavy snow and strong ridgetop winds. Storm slabs could become easy to trigger and grow in size as snow accumulates. The new snow load may also increase chances for triggering very large and wide slab avalanches over two feet deep on old snow layers. Step it way back, and default to lower angled slopes as the winter storm passes through.

Problemi valanghivi

  • Storm Slabs

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

    Monday is a good day to steer clear of steep open slopes as a winter storm pushes through. Seek out lower angled and less exposed slopes. Moderate to heavy snowfall and strong winds should add up during the day. There could be interstorm layers that don't bond well as it falls, and winds could create more cohesive slabs in exposed locales. As more snow adds up during the day, the potential size and likelihood of avalanches should increase. Localized heavier snowfall could occur over the pass during the day, and natural avalanches may occur. Loose avalanches should also be considered during times of heavy snowfall rates.

    Look for signs of instability like shooting cracks and fresh slab avalanches. Check to see how the new snow is bonding with practical tests. 

    (2/7/2023)

    Example storm slab

    Photo: Dallas Glass

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–3

    The new snow may increase chances for natural and human triggering of large to very large slab avalanches a couple feet deep. You're not likely to get direct signs of instability with this situation, but if you triggereed one it could be surprising and destructive. These have occurred most recently from large, open and somewhat unsupported slopes. Persistent weak layers in the form of weak snow from early February and slick crusts from January have been active for the past week.

    With this problem lurking, default to well supported terrain features and practice safe travel techniques while the storm rolls through.

    (2/12/2023)

    Very wide crown spanning most of the south face of Jove Peak. This slide very likely occurred during the middle of the day on Sunday.

    Photo: Julia

Avalanche Discussion

A new, large and wide crown from a slab was observed off the S face of Jove Peak on Sunday, we're unsure of the timing when this happened but it may have been fairly recent. On Saturday, a report came in of a large skier triggered slab on a northeast aspect at around 5,400ft just north of Lake Josephine. The second skier on the slope triggered the slide in a steep, unsupported feature, and the crown broke above him. The skier was carried over a hundred feet and buried, all except his boots. The crown averaged 24" and was an estimated 100ft wide. Josh and Irene investigated the slide on Sunday and will post more details. Another skier triggered slide occurred on the 9th from a nearby slope to the above mentioned involvement. These incidents speak to continued instabilities and lack of bonding of recent storm snow to older weak snow and crusts. 

February 8th was very active, and control work at the ski area that day produced widespread storm slab results, 3 were reported to have run down to a recent crust. Observers also reported large, natural slab avalanches on steep, leeward slopes, just below ridges that saw wind loading including Windy Ridge and the Rooster Comb, above Lake Susan Jane. A couple of these also were suspected to have run on recent crust interfaces as well. 

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