Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Another spring day is in store for the East North zone on Easter Sunday. If you see new rollerballs or snow shedding from trees and rocks, hop over to shaded slopes with less wet avalanche potential. Limit your time spent under overhead hazards such as sagging cornices.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    If you're going to trigger an avalanche in dry snow, it will likely be in wind-loaded terrain. Sunday should be a touch windier than Saturday, so you might see new shallow slabs developing or actively blowing snow. Otherwise, you'll be dealing with lingering wind slabs from the past few days. Wind slabs commonly form in confined chutes, on convex rollovers, or near the base of cliffs/rocks. Look for visual clues such as textured surfaces, smooth pillow-like drifts, or new cornices to help identify wind-loaded features to avoid. Using small test slopes can give you information about how these slabs may be reacting to your weight.

    (3/28/2024)

    Shooting cracks in shallow wind slab.

    Photo: Willie Webster

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Wet avalanche activity will remain the primary concern on Sunday. The sun and warm temperatures will likely need to break down a surface crust. Once that happens and the snow becomes wet and weak, you'll start to see rollerballs, pinwheels, and eventually wet avalanches. We expect the majority of these slides to be loose avalanches, which often start at a point near rocks or trees. They can grow large and powerful as they descend and gather snow. In some areas, they could even trigger slabs. Your best management tool will be to stick to shaded slopes to avoid these difficult-to-predict slides.

    In isolated locations, larger, more unpredictable shed-style avalanches could occur. Cornice collapses, glides, or even wet slabs could happen over the next few days. Keep an eye on the terrain above you, and don't linger where you see precariously hanging blocks of snow. Give cornices plenty of space; they are notorious for breaking back further than you might expect.

    (3/28/2024)

    D2 + Wet avalanche debris which released during the March 14th-20th warm-up

    Photo: Willie Webster

Avalanche Discussion

Preliminary Report: NWAC is saddened to report an avalanche fatality as a result of a cornice fall on Mount St. Helens. On Saturday, March 30, 2024, a snowboarder summited the peak. While standing near the top, he triggered a cornice and fell to his death. Our deepest condolences to the family, friends, and community. 

Discussion:

Sunday is expected to be similar to Saturday, except with a bit more wind. That could help bring wet avalanche activity down a notch, or increased sunshine may keep the party rolling. One thing is certain: the potential for avalanches will not be eliminated. An increase in activity and possibly size is anticipated for Monday as temperatures skyrocket and we lose the wind.

Take these predictions with a grain of salt. It can be challenging to pinpoint precisely when wet avalanche cycles will peak. Often, we see activity wax and wane during these multi-day warm-ups. Sunday will be another day when the likelihood of dry avalanche problems diminishes, replaced by wet avalanche concerns. Continue to stay vigilant and know that at some point over the next few days, larger and more dangerous avalanches will occur. Cornice collapses, wet slabs, glides, and other shed-style avalanches usually start to peak after a few days of warm and sunny weather.

This brings us to our main uncertainty surrounding this warm-up period. While we anticipate most avalanche activity to occur in the snow above the 3/22 melt-freeze crust, there is some concern about older, persistent weak layers. We recently removed this problem from the forecast, thinking they are dormant. However, observations indicate that the structure still exists in isolated locations. No red flags of instability have been reported, such as recent avalanches. That said, a widespread avalanche cycle occurred on these layers last time we had a significant warm-up. If you want to minimize your exposure, make travel plans limiting time spent in large, complex, and unsupported start zones. This layer may be more active in high-elevation northerly terrain or areas further east in the zone, such as the Pasayten or Harts Pass.

Snowpack information is limited. Let us know what you find if you get out into the backcountry!

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