Avalanche forecast

West Slopes South

Northwest Avalanche Center
View on map

Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
Open full map
Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Let the snow surface guide your decision-making on Friday. If the snow is heavy and wet or you see fresh rollerballs and pinwheels, think about wet avalanches on slopes over 35 degrees. Around the zone, a poor snowpack structure still exists on shaded slopes as you ascend in elevation, so think twice before committing to this terrain.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1

    If the snow surface gets wet and sticky on Friday, think about wet avalanches on slopes over 35 degrees. You can try to push on the snow on small test slopes to see if it is “ripe” and ready to slide downhill. You can also get off your mode of travel and step into the snow to see if you are sinking in past your ankle. If so, you will know there is enough heavy snow to create a Wet Loose avalanche. These slides often start at a point before fanning out as they descend downhill. Look for recent fan-shaped debris piles or fresh rollerballs and pinwheels as visual clues to help you identify that these slides are possible.

    (3/24/2022)

    Take a moment to step off your mode of travel to see how deeply you are plunging into the snow. If you are sinking in past your ankle, start to think about wet avalanches. 

    Photo: Dallas Glass

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–2.5

    At this point, it has been about a week since our last confirmed avalanche on the 3/8 facets in the West South zone. The poor snowpack structure still exists throughout the zone, but the lack of confirmed avalanches and improved snowpack tests have given us some confidence to drop the problem to unlikely. That doesn’t mean that large avalanches can't still happen on this layer. Be cautious on upper elevation shaded slopes where these weak snow grains are thought to be more prevalent. Just because there are tracks on a slope or you aren’t getting impressive test results in your pits doesn’t mean that conditions are safe. Persistent slabs act in surprising ways and can wake up without warning after sleeping for multiple days.

    (3/18/2022)

    A skier triggered avalanche on Mazama Ridge near Paradise, Mt Rainier NP. 16" deep. W aspect, 5600ft. This avalanche faild on the 3/8 facets over the Early March Crust. HS-ASu-D2-R3-O

    Photo: Public Observation

Avalanche Discussion

Cloudy weather should battle with springtime temperatures in an attempt to soften the snow surface on Friday. Without the aid of sunshine, we suspect that the cloudy weather should win and help to keep wet avalanches at bay. Taking note of the snow surface throughout the day can help you make terrain decisions and set the tone for your time in the mountains.  If you find that the surface is firm and mostly supportable, the avalanche hazard should be minimal. If you are plunging in deeply on a poorly frozen surface, the likelihood of you triggering a Wet Loose avalanche may have increased.

The threat of a persistent slab is driving the Moderate danger within the zone. NWAC forecasters at Mount St. Helens on Thursday found the poor snowpack structure on upper elevation shaded slopes, but had unimpressive test results on the 3/8 facets. On the flip side, this layer awoke in the West North zone during a spell of warm weather on Wednesday and produced a very large avalanche. Does this mean that the layer is waking up region-wide? These facets are sitting just above the Early March Crust, which marks the lower bound of our current layers of concern (around 3 feet below the surface). Apart from the persistent issues, we are mostly focused on the surface snow and its transition toward a more springlike snowpack. This hasn’t happened quite yet, but after a few more freeze/thaw cycles, we can probably start to put those lower weak layers to bed and focus on the diurnal nature of the snowpack.

Regions covered