Consider avalanche danger to be HIGH in areas that receive rain on top of 30 cm or more of dry snow. Avoid exposure to avalanche terrain during periods of rapid loading by rain, snow, or wind.
Confidence
Low - Due to the number of field observations
Weather Forecast
We'll see lingering flurries on Monday as freezing levels come back to more seasonal values. Unsettled weather with scattered flurries for the remainder of the forecast period. MONDAY: Cloudy with isolated flurries. Moderate to strong westerly ridgetop winds. Freezing level around 1000 mTUESDAY: 5-10 cm of snow. Moderate to strong westerly ridgetop winds. Freezing level around 1300 mWEDNESDAY: Scattered flurries. Strong westerly ridgetop winds. Freezing level rising to around 1200 m.
Avalanche Summary
On Saturday, no new avalanches were reported in this region. Natural avalanche activity is expected on Sunday into early Monday in areas where rain falls on dry snow. We currently have very limited observations in this region. Please submit your observations to the Mountain Information Network (MIN).
Snowpack Summary
A new crust formed on Thursday as temperatures cooled and the rain-soaked snow surface froze. Since then 15-30cm of snow has fallen at treeline and above. The new snow has created fresh storm slabs sitting on a crust. The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 150+cm in the alpine, 100-150cm at treeline, and decreasing rapidly below treeline where the primary hazards are rocks, stumps, and open creeks. A major feature in the snowpack is a crust which was formed around Halloween, and may be found approximately 100cm down at treeline elevations. We currently have very limited snowpack observations within this region and it is critical to supplement this information with your own observations.
Problems
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.
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.