Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

One last day of sunny skies and warm temperatures will continue the trend of midday softening on steep southerly slopes. Wet snow avalanches could occur in these areas when the snow softens and you’re sinking in past your ankles, or if you see rollerballs running down a slope. On other slopes, surfaces will remain frozen where you’ll most likely be encountering a firm, bumpy crust. 

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Small, wet loose avalanches occurred midday Saturday on steep, south-facing slopes. Many originated in rocky areas, then fanned out on slopes below. They were mostly small in size. Expect similar conditions Sunday before clouds increase in the afternoon. 

    A major player in how soft surfaces are getting is the angle of the slope relative to the sun. The more direct of an angle, the more the snow will soften and get wet. Low angle or flat surfaces are not softening much, but shift just a little to steeper south-facing terrain and all of a sudden you’ll find much softer snow by about 10am onwards. The surface may break down enough so that you’ll sink through the loose, moist layer beneath, all the way to the late January crust around a foot deep. Before this starts happening, shift off the steep, sunny slopes. If you see avalanches or rollerballs, stay off similar slopes as well.

    (2/12/2022)

    Wet loose avalanches which occurred Saturday in the West North Zone on a south facing slope at~6000ft. 

    Photo: Lee Lazzara

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–2.5

    The persistent weak layer, buried around 1-2 feet below the surface, is still present on upper elevation northerly slopes. It exists in areas where the warm, wet weather only impacted the surface, forming a thin surface crust and the underlying layers stayed dry. Recent natural avalanches were found in the West North zone, probably failing on this layer, in conditions similar to what we’re seeing in the West Central Zone. 

    If you’re on steep, north-facing terrain at upper elevations, pay attention to how thick the surface crust is. Where the crust is thinner (an inch or less), the weak layer may still exist at about two feet deep, just above the Late January Crust. So far, we’ve found that you can get away with traveling on many steep slopes without causing an avalanche, but there is a very small chance that you could trigger an avalanche on that layer if you find just the right spot on the slope. It’s important to consider this if you’re planning on heading to steep upper elevation northerly terrain, as you might be taking a bit of a gamble on steep slopes.

    (2/12/2022)

    Large (D2) natural slab avalanche on a north aspect at 5500' in the West North zone, similar to what we might see in the West Central Zone. This is suspected to have released in the late January crust-facet layering  a couple days ago. 

    Photo: Lee Lazzara

Avalanche Discussion

Stay alert for large cornices baking in the sun. A cornice fall itself would be scary, but it also could be a large enough trigger for an avalanche on the persistent weak layer if it’s on the right slope. Give large cornices a wide berth.

Sunday night will rapidly cool to a freezing level of 3500ft by Monday morning. We’ll receive a burst of snow early Monday, amounting to about 6 inches, just enough to pad the hard surface. Until then, beware of the firm, variable surfaces present in most areas.

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