Welcome to winter! It's that time of year when winter is slowly winding up and observations are limited. Due to limited data it is CRITICAL to supplement this information with your own observations. Please post your observations to the MIN.
Confidence
Low - Due to the number of field observations
Weather Forecast
FRIDAY: Mostly cloudy with isolated flurries, light to moderate southwesterly winds, freezing levels around 1500m. SATURDAY: Mostly cloudy with isolated flurries, light southerly winds, freezing levels around 1500m. SUNDAY: 5-15cm new snow throughout the day, strong southwesterly winds, freezing levels rising to around 2400m.
Avalanche Summary
On Wednesday, no new avalanches were reported in this region. However, we currently have very limited observations in this region. Please submit your observations to the Mountain Information Network (MIN).
Snowpack Summary
Fresh wind slabs may have formed below alpine ridgetops in areas where the precipitation fell as snow on Thursday afternoon. The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 200+cm in the alpine, 100-150cm at treeline, and decreasing rapidly below treeline where the primary hazards are rocks, stumps, and open creeks. Recent heavy rain to the mountaintops has rapidly shrunk the snowpack and has transitioned much of the snowpack from dry to moist snow. The major feature in the snowpack is a crust which was formed at the end of October and can be found approximately 100cm down at treeline elevations. However, freezing levels are forecasted to drop dramatically by Friday morning which will likely create a strong crust at most elevations and decrease the likelihood of triggering avalanches on the October crust. We currently have very limited snowpack observations within this region and it is critical to supplement this information with your own observations.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.