Bulletin d’avalanche

West Slopes South

Northwest Avalanche Center
Voir sur la carte

Danger d’avalanche

Sun
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
Open full map
Périmé — ce bulletin a expiré 6 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

New snow will fall on weak surfaces associated with a crust. That's a great recipe for sensitive avalanche activity. Even small slides can have serious consequences when terrain traps are involved.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    Typically, we don't forecast storm slab unless more significant snowfall is expected. However, weak surfaces are widespread within the West South zone, meaning you'll need to be leery of triggering avalanches on most slopes over 35 degrees. The majority of these slides should be relatively small, but they could break in surprising ways by spanning far distances, connecting terrain features, or even breaking above you. If you see shooting cracks, hear whumpfing collapses, or find heavy snow over weaker snow in your handpits, be leery of steep slopes. 

    With some gusty winds associated with this storm, you may find that slabs are thicker and potentially more reactive in wind-loaded terrain. You can use many of the same tests to look for instability, but you should also use visual clues, such as actively blowing snow or fresh drifts, to help identify wind-loaded features to avoid. If the snow is firm and hollow feeling, you may have found a hard slab. These are more difficult to assess, so retrace your steps and find a new route.

    (2/10/2026)

    A natural wind slab avalanche on Mount St. Helens this week. This one is on a relatively small slope and just touches the uphill travel route.

Avalanche Discussion

Winter lovers rejoice, it's going to snow a few inches in the West South zone on Friday night! New snowfall amounts won't break any records or bring us back to seasonal norms. But this is the second weekend in a row with measurable snowfall, and very little to no rain is expected. 

With weak snow identified on and near the surface before this storm, whatever falls on Friday night could fail easily on Saturday morning. Weak grains such as surface hoar and near-surface facets are either resting on or just above the 2/7 crust. The depth of this interface varies with aspect and elevation. Down low and on sun-exposed slopes, last week's snow may have undergone enough freeze-thaw cycles that it is now joined with the 2/7, forming a single complex. As you gain elevation or move toward shadier aspects, it may be as much as 8-15 inches down by Saturday morning. That's not a lot of depth over the 2/7 to create potential avalanches, but they could be touchy. The bond at this interface is weak, creating a second potential failure point in the upper snowpack below the newly developed 2/13 interface. 

The 2/7 crust is more than just a good bed surface for potential avalanches to run on. It doubles as a tricky layer to travel over. New snow should improve travel conditions, but open holes, creeks, firm crust, exposed rocks, and other natural hazards remain widespread in the mountains. 

We know how much you all love NWAC. We love you, too. But in lieu of chocolates or flowers, you can show us how much you care by submitting an observation this Valentine's Day. Let us know whether those weak surfaces are buried intact or if you see the new snow failing easily.

Régions couvertes