Avalanche forecast

West Slopes South

Northwest Avalanche Center
View on map

Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
Open full map
Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

A strong winter storm should bring dangerous avalanche conditions to the West South zone by Saturday morning. This is a good day to dial it back and let the storm play out by avoiding all steep open slopes. Many of these avalanches could grow large enough to bury you. 

Very dangerous avalanche conditions could develop on Mt St Helens. Travel in avalanche terrain is not recommended in this area.

Avalanche problems

  • Storm Slabs

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

    This storm checks the boxes: significant snowfall, high precipitation rates, strong winds, and fluctuating temperatures. It's a classic setup for avalanches on any open slope greater than 35 degrees. You can use small slopes and hang pits to test the new snow as you travel and see how it’s bonding to the underlying interface. If you see it crack, fail suddenly, or slide in block-like slabs, you’ve located the problem. On many slopes, the new snow may struggle to bond to a firm crust. Avalanches in these areas could fail easily and run quickly on this potential bed surface. 

    While we expect to see avalanches in a variety of locations, they will likely be larger and harder to manage in wind-loaded terrain. You could encounter firm thick slabs along exposed ridges and near the base of cliffs. Unless it’s wind-scoured, be particularly careful in possibly wind-loaded terrain where avalanches may break above you.

Avalanche Discussion

Mt St Helens is taking the brunt of this winter storm with substantially more snowfall than anywhere else in the zone. This will likely combine with very strong and gusty winds to create very dangerous conditions that may last well into Saturday. This includes the large natural avalanches that can run far and fast on an underlying crust. Stay away from places where avalanches start, run, and stop. 

Across the West South zone, the bulk of the precipitation and strongest winds should occur Friday night. That means dangerous conditions will likely exist right off the bat Saturday morning. You may see the hazard spike again during heavier snow showers or periods of intense blowing snow.  Convective showers could cause this to occur anywhere in the zone. One way to manage this unpredictability is to choose routes that let you easily return to the trailhead without needing to cross complex or high-consequence terrain. 

Given the current snowpack structure, we’re primarily concerned about avalanches failing at or above the new/old interface (3/31). As we mentioned this is often marked by a firm crust. However, textured surfaces, scoured slopes, wind-pressed snow, and settled powder were also reported before this storm. Given the variability, make lots of observations as you travel, and don’t base your decisions on a few isolated tests. 

While we expect continued showers to keep the skies cloudy, it’s April, and the sun could make an appearance. If you start to notice the sun, odds are, so is the snowpack. Watch out for natural loose wet slides occurring from steep rocky terrain. These small avalanches could also trigger slabs on the slopes below. 

Regions covered