Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Firmer wind slabs may hide under a few inches of softer snow on Monday. Look for clues like larger drifts, rime, or the snow plastered to trees to determine local wind patterns and anticipate those wind-loaded slopes you want to avoid.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    For most of the zone, the avalanche concerns will occur in wind-loaded terrain. However, as the winds decrease significantly on Monday morning, additional snowfall could mask this hazard. It may take looking a bit closer for signs of wind drifting snow. Expect slabs along ridges, near the base of cliffs, in the tops of chutes, and on very exposed mid-slope features. Since it’s hard to tell exactly where the wind slabs are (and are not), give potentially wind-loaded slopes a wide berth, especially if they end in higher consequence runouts. 

    At Mt Rainier, substantially more snow could lead to avalanches failing even in wind-sheltered terrain. Slabs could release within or near the base of the new snow. Use small test slopes to see how the snow reacts to your weight. 

    In both cases, weak snow (surface hoar, facets, and dry powder) was seen before this storm. Since they were variably slope to slope, certain features may react differently than others. If slides fail on this interface (2/11), avalanches could trigger easily and propagate wider than expected.

    (12/30/2023)

    Example: Snow plastered on a tree trunk and small drifts help show the local wind direction. 

    Photo: Dallas Glass

Avalanche Discussion

This storm has a lot of variability across the West South zone. The lion’s share of the snow should fall on Mt Rainier, with significantly less near Mt St Helens, Mt Adams, White Pass, and Crystal. By lunchtime Monday, Rainier could receive 12-15 inches of snow. You may experience more dangerous conditions near Paradise or in the Tatoosh range. Elsewhere, storm totals will likely peak around 3-6 inches over the 2/11 interface. 

This new snow will add to the totals from the past week and continue to bury the Early February Crust. You will often find the EFC about 8-12 inches (20-30cm) below the surface. On more southerly aspects, sunshine on Saturday formed a crust at the 2/11 interface. On more shaded slopes, you could find surface hoar or facets at this interface or even on top of the EFC. 

On Sunday, NWAC forecasters and avalanche professionals around the zone reported an inch or two of new snow. At Mt Rainier, where precipitation was heavier, a few small natural wet loose slides occurred. Winds increased during the day across the zone and began drifting the recent snow, particularly in the afternoon.

Regions covered