Bollettino valanghe

East Slopes Central

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

Overlapping avalanche problems, increasing freezing levels, and a known weak layer will make for a dangerous Monday. Keep your terrain selection simple, especially if you notice rain on dry snow or other signs of instability, such as recent avalanches, audible whumphs, or shooting cracks. 

Problemi valanghivi

  • Storm Slabs

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

    If you find yourself at upper elevations or traveling early enough in the day, you may need to navigate around dry snow problems such as sensitive storm slabs or wind-drifted snow near ridgelines. Some of these slabs may break in surprising ways, especially in areas where they rest on top of weak, sugary snow from November. These avalanches will likely break 1-3 ft and take out all the recent snow since the 30th. 

     You can use quick hand pits or small test slopes to gauge how sensitive the new snow is. Shooting cracks, audible whumphs, or better yet - recent avalanches are all obvious signs that you found an unstable slab. 

    A complicated snowpack and an active weather pattern should help keep your terrain selection simple. Just consider avoiding all avalanche terrain at middle and upper elevations until the storm has run its course. 

    You may be able to trigger soft slabs like this at mid and upper elevations on Monday.

    This avalanche occurred in the Mission Ridge area on Sunday.

    SS- AK-R2- D1-O  on NE aspect, 6000 ft

    Photo: Drew Carleton

  • Loose Wet

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

    As the day progresses, it will only become more warm and wet -  setting the stage for wet snow problems. You may initially notice a round of wet loose avalanches, but remember, these smaller avalanches are usually a precursor to larger and more destructive wet slab avalanches. 

    Once it starts raining or warms above freezing, consider pulling the plug on any avalanche terrain at middle and upper-elevation slopes. Rain on a dry snowpack, with a known weak layer - could make conditions dangerous quickly.

     

    (4/9/2023)

    Example of a wet snow avalanche from last season. 

    Photo: Matt Primomo

Avalanche Discussion

A complicated weather forecast makes for a complicated avalanche forecast. The big question for Monday will be the timing of the rain across the east central. If you're further north, you may escape the rain until evening. However, if you find yourself further south, like Salmon La Sac or the Wenatchee Mountains, you may deal with rain and more dangerous conditions early in the day. 

Observers reported endless signs of instability across the region this weekend. On Sunday, the Mission Ridge Pro Patrol reported propagating slabs and touchy conditions. These slabs generally failed 6-12 in deep and upwards of 2 ft in wind-loaded areas. These slabs failed on the old weak snow from November. Observers in neighboring zones have reported widespread avalanches, failing on faceted snow from November. This kind of bullseye information tells us our structure is poor and will only become more dangerous as we start introducing rain. 

Before this week's storm, snow cover was minimal to nonexistent below 4,500ft, especially on sun-exposed slopes. Depending on where you go, the chance to hit buried rocks, logs and other obstacles may still prove a significant hazard. 

You can add to the forecast! Please let us know what you see in the mountains by submitting an observation.

 

 

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