Regions
Kootenay Boundary.
New snow and southerly winds will be driving the avalanche danger on Tuesday. Due to limited data it is CRITICAL to supplement this information with your own observations. Please post your observations to the MIN.
Confidence
Low - Intensity of incoming weather systems is uncertain
Weather Forecast
The next system arrives on Tuesday with modest amounts of snow and more seasonal freezing levels. TUESDAY: Snow (10-15 cm) during the day with another 5-10 cm possible overnight. Moderate southerly ridgetop winds. Freezing level around 1000 m.WEDNESDAY: Clearing throughout the day. Moderate westerly ridgetop winds. Freezing level around 1200 m. THURSDAY: Cloudy with isolated flurries. Light to moderate southwesterly ridgetop winds. Freezing level around 1000 m.
Avalanche Summary
No new avalanches reported; however, we currently have very limited observations in this region. Please submit your observations to the Mountain Information Network (MIN).
Snowpack Summary
Anywhere from 2-10 cm of snow fell Sunday overnight into Monday, as temperatures dropped by 5-10 degrees (and back to more seasonal values). Ridge top winds were moderate from the west and likely formed wind slabs on lee (easterly) slopes.This new snow fell on a 2 cm thick melt-feeze crust, which could become a good sliding layer when more snow falls on Tuesday. The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 100-170cm in the alpine, 50-100cm at treeline, and decreasing rapidly below treeline where the primary hazards are rocks, stumps, and open creeks. Last week's heavy rain to the mountaintops really shrunk the snowpack and has transitioned much of the snowpack from dry to moist snow. A major feature in the snowpack is a crust which formed at the end of October and may exist approximately 30cm above the ground in some locations. That said, the latest crust (November 27th) will temporarily reduce the likelihood of triggering on this layer. 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.