Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

Continued stormy weather will impact the West South zone on Saturday with higher precipitation totals expected on the volcanoes. If you notice the snow is piling up or being drifted into a cohesive slab by the wind, be sure to check its bonding to the old snow surface before stepping into consequential terrain.

Avalanche problems

  • Storm Slabs

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

    Another round of snow and wind could combine to create Storm Slabs on Saturday throughout the West South zone. Areas receiving the most precipitation, such as the volcanoes, should develop larger and potentially more reactive slabs. Regardless of your location and slab depth, take the time to use hand pits and test slopes to check the bonding of the recent storm snow to the old snow surface. If you find that the new snow is poorly bonded to the old surface or there is cracking in the snowpack as you travel, steer around steep terrain features over 35 degrees, rocky terrain, or wind-loaded features where you could trigger an avalanche more easily.

    (12/16/2020) Skin track test showing cracking in the surface snow. This can indicate storm slabs are present.

Avalanche Discussion

The first wave of storms on Thursday night brought around 4” of snow to Paradise, with closer to 2” near the crest at Crystal and White Pass. More waves of precipitation and wind are forecasted to impact the zone throughout the weekend, and by the end of the day on Saturday, we could be looking at close to a foot of snow since these storm waves began. The highest snow totals should continue to be found on the volcanoes, with over 1” of SWE forecasted for Paradise. There is always uncertainty when forecasting precipitation, but springtime forecasting and poorly developed storm systems tend to lead to even more uncertainty than usual. That said, it’s been well documented that there is a generally strong snowpack around the West South, and avalanche hazard over the weekend will generally be driven by new inputs from snow, rain, or wind. We're hedging our bets that the weather forecast on Saturday produces enough snow and wind during the day that you will be able to trigger small avalanches at middle and upper elevations throughout most of the zone. On the volcanoes, some of these slides could grow large if we reach or exceed our forecasted water amounts. Regardless of the amount of new snow received in your area, it will be falling on a variety of surfaces. These surfaces vary based largely on aspect or elevation and include firm melt-freeze crusts, wind-stiffened snow, breakable crust, or potentially faceted snow. Take the time to investigate the bond between any new snow and the old surface by using test slopes and hand pits as you travel. Depending on what surface the snow falls on, it could behave differently given a human trigger, including running far and fast on slopes that contain a firm crust for a bedsurface. We'd love to hear what you're finding out there, so let us know by submitting a public observation.

Continue to stay vigilant with your route planning this spring, avoiding overhead hazards such as cornices and glide slopes as much as possible. Although these avalanches are more likely during periods of warmer weather, they are unpredictable and could fail due to a variety of reasons.

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 closer to home.

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