Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

Another round of snow and wind should strike the West South zone on Sunday, potentially resulting in Wind Slabs for you to manage. Actively blowing snow can key you into features that could contain unstable mounds for you to avoid. Areas further south are forecast to receive the bulk of this storm and may have locally higher avalanche hazard.

Avalanche problems

  • Wind Slabs

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

    Additional snowfall and gusty winds could result in a fresh crop of Wind Slabs for you to manage on Sunday. Look for actively blowing snow creating fresh cornices and deeper drifts as you ascend in elevation. You could encounter wind-loaded features near ridgelines or rocky terrain such as confined gullies or the base of cliffs. Just because slabs weren’t reactive first thing in the morning, doesn’t mean they’ll be like that all day. They may be more likely in the afternoon hours as the wind direction changes and speeds increase. This should coincide with a period of heavier snow showers. The caveat is, of course, the volcanoes, where higher snowfall accumulations and stronger winds are possible throughout the day. Regardless of the time of day or your location in the zone, you can use small test slopes to see how the snow is reacting to your weight and look for textured surfaces or areas that look “fat” to help you identify the wind-loaded features you should avoid.

Avalanche Discussion

Friday night’s storm didn’t deliver the snowfall amounts for the volcanoes we expected, but that might change on Saturday. Another round of snow and wind is set to impact the zone, specifically the southern portion. If you’re headed to the southern volcanoes such as Mt. Adams or Mount St. Helens, be sure to check out the Mount Hood forecast, you could find that conditions more closely align toward Considerable danger. Mount Rainier may be right on the cusp, depending on the storm track. 

Generally, around 3-4 inches of new snow fell around the zone on Friday night through Saturday afternoon. This brings storm totals somewhere in the 5-7 inch range since Friday morning. Observations from Saturday indicate that the snow is heavier and wetter at lower elevations and loses moisture content as you ascend. Drifting, cracking, and firmer wind-pressed snow was reported at upper elevations at White Pass and Mount Rainier National Park. Crystal Mountain Pro Patrol reported triggering some small Wind Slabs during their morning mitigation work, but no other avalanches were reported within the zone.  Rollerballs and pinwheels were reported at lower elevations in most locations - an indication of Wet Loose avalanche potential. You could find similar conditions on Sunday. 

The new snow was reported to have varying degrees of bonding to the old snow surface. Firm crusts, wind-pressed snow, and weak faceted snow were all reported prior to this storm. We anticipate Saturday night’s snowfall to bond fairly well to the wet and warm surfaces, but as snow showers and wind speeds are renewed in the afternoon hours, you may see more slab development. At upper elevations where the snow is drier, you will need to spend more time investigating the bond. The incoming snow will further increase the load on the 3/2 interface and we anticipate the majority of avalanches to occur at or above this layer. We are still watching some deeper layers above the MLK crust, but do not think this storm will be the one to tip the scales.

Regions covered