Recently formed storm slabs may still be reactive to human triggers. Use additional caution in shallow, rocky, or wind affected alpine terrain.
Confidence
Low - Due to the number of field observations
Weather Forecast
Tuesday: Mix of sun and cloud / light southerly winds / Freezing level around 900m. Wednesday: Possible flurries / Light westerly winds / Freezing level around 1200m. Thursday: Mix of sun and cloud / Light northwesterly winds / Freezing level around 900m.
Avalanche Summary
No new avalanches were reported in this region on Sunday. However, a natural size 3 and several size 2 avalanches were reported on the east side of Rogers Pass in the highway corridor.
Snowpack Summary
30-70 cm of recent snow formed storm and wind slabs that were reactive to human triggers over the weekend. These slabs will likely become less reactive in the coming days but will still require careful slope by slope evaluation. Reports suggest the the mid-November crust down 60-120 cm is well bonded to the overlying snow. Below the crust the snowpack is generally well settled. Limited observations suggest snowpack depths vary greatly throughout the region and are on average 100-180 cm at treeline elevations with generally less snow in the southern portion of the region.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.