Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The avalanche danger will increase significantly as you ascend to places with more snow and stronger winds. If you start to see signs cracking, up-side-down, or blowing snow assume these conditions will only get worse as you move higher. Sticking to lower angled or treed terrain will help you manage these issues. 

Problemi valanghivi

  • Storm Slabs

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

    This isn’t a huge storm, but it checks several boxes. Some places in the zone could see 6-12 inches of new snow, warming temperatures, and moderate winds. The storm snow could fall on a variety of surfaces including slick crusts and possibly weak dry snow. On Tuesday, human, remote, and naturally triggered avalanches were reported. Look at every steep slope as suspect until you are convinced otherwise. 

    What could help sway you? Measure the recent snow. If you have less than 8-12 inches you probably don’t have a significant storm slab issue. Use hand pits, uptrack tests, and small slopes to see how the new snow reacts. If it cracks or fails in blocks, then you’ve found the problem. Make sure to look all the way down to the stout atmospheric river crust. In a few spots, slabs could fail or step down to this older layer. 

    Even if you don’t find 8-12  inches of snow, or you don’t find slabs in sheltered terrain, moderate winds will likely create a hazard on exposed slopes. Wind slabs may be firmer and deeper than surrounding areas. Watch for blowing snow and small drifts to point toward potentially dangerous slopes.

    One of several human, remote, and natural slab avalanches from the Cyrstal backcountry on Tuesday. (3/11/2025) 

Avalanche Discussion

None of these storms have been or are particularly impressive, but they keep bringing a few inches here, 6 inches there. We’ll take it! Tuesday night’s storm falls right in that theme. With southerly flow, places like Mt Saint Helens, Paradise, and Crystal Mt could receive the highest snow totals. In locations that don’t pick up 8 inches or more of snow, expect less dangerous conditions. In these spots, the issues could be the same, but the avalanches should be smaller. 

A bump in temperatures Wednesday afternoon could cause the snow levels to rise. We aren’t worried about rain on snow at lower elevations (these snowpacks have been through a lot). However, near the rain-snow line, wet heavy snow could result in rollerballs and small wet loose avalanches. 

Avalanche concerns should be limited to the snow above the stout and thick atmospheric river (AR) crust.  This is basically the new ground. What’s impressive is the variation in the upper snowpack despite its relatively shallow depth. Some slopes may be scoured down to this icy surface, while others hold layers of recent snow, melt-freeze crusts, and potentially even spotty surface hoar. Some of the avalanches reported near Crystal Mountain on Tuesday highlight this variable and potentially challenging snowpack. This variability could make it hard to predict exactly how any one slope will react. 

Regioni coperte