Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Look for stormy weather to increase the avalanche danger throughout the day Wednesday across the West South zone. When you find more than 6” of new snow or encounter wind drifted slabs, dial back your terrain use and steer around similar slopes greater than 35 degrees.

Avalanche problems

  • Storm Slabs

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

    The heaviest snowfall and strongest winds should coincide with warming temperatures Wednesday. This may quickly form slabs that you can trigger. You’ll need to monitor and anticipate the changing conditions. When you measure more than 6” of new snow, find a poor bond to the old surface, or notice the wind actively loading slopes, recognize conditions may be reaching their tipping point. Start dialing back your terrain by avoiding likely trigger points: convex rollovers, rocky areas, and slopes below cornices. As the snow gets deeper or you begin to see cracking and an upside-down surface, avoid all avalanche startzones. You may trigger larger avalanches later in the day and/or in locations where the wind builds deeper slabs. Because of the dynamic conditions, make sure to consider how you will travel back to the trailhead and what conditions you could encounter while planning your day.

    (2/15/2021) Example: Small slopes like this can help you observe the growing storm slab hazard. [SW 4700', Cortwright Butte; SS-ASc-R2/D1-N]

Avalanche Discussion

The stormy weather should begin in the pre-dawn hours and you may even find a few inches of snow at the trailhead first thing in the morning. This likely won’t be enough to present a real hazard. Expect the snowfall and winds to really ramp up by mid-day. This could bring a very quick rise to the avalanche danger. The hazard should peak in the afternoon and during periods of more intense precipitation. Locations near the volcanoes are expected to receive the most new snow. Other locations may experience slightly lower avalanche danger. This new snow will accumulate on a wide variety of snow surfaces that may include crusts, facets, surface hoar, and settled snow. This may cause the snow to respond very differently from one slope to the next. You could see avalanches fail very easily if they occur over weak persistent grains. 

At lower elevations, you may find that the mild temperatures limit accumulation and that the new snow quickly settles. Because of this, we anticipate smaller and harder to trigger avalanches in these areas. Rain could impact sections of the below treeline band. If you find yourself near the rain-snow line or encounter wet heavy snow, don’t be surprised to see new rollerballs or small loose wet avalanches. 

Recent storms (3/18-3/23) deposited 1-2.5 ft of snow around the West South zone. Tuesday’s partly sunny and mild weather likely causes the surface snow on E-S-W aspects to become wet and heavy. Small natural loose wet avalanches may have also occurred. This likely created a very aspect dependent snow surface as we head into this next storm. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating clos

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