Avalanche Forecast
Issued: Nov 30th, 2018 3:17PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs.
jsmith,
Avalanche Canada
There is a lot of uncertainty with the reactivity of the buried surface hoar layer down 40-80 cm. Human triggered avalanches are more likely at treeline and sheltered locations in the alpine where this weak layer exists. New Forecaster blog HERE.
Summary
Confidence
Low - Due to the number of field observations
Weather Forecast
Overnight FRIDAY: Mostly cloudy / Alpine Low -11 / Light, southwest wind / Freezing level valley bottom.SATURDAY: Mostly cloudy / Alpine high -11 / Light, northeast wind / Freezing valley bottom.SUNDAY: Mix of sun and cloud / Alpine high -11 / Light, northwest wind / Freezing level valley bottom.MONDAY: Mix of sun and cloud / Alpine high -13 / Light, northwest wind / Freezing level valley bottom.
Avalanche Summary
No avalanches were reported in this region on Thursday. However, we currently have very few observations from within this region. Please post your observations to the Mountain Information Network. (MIN)
Snowpack Summary
Recent storm snow amounts range from 40-70 cm. There may be some lingering wind slaps in exposed, alpine terrain, but the primary concern in the snowpack is a weak layer of surface hoar (feathery crystals) and/or sun crust depending on the aspect of the terrain. This layer is below the recent storm snow and is down roughly 30-70 cm. The surface hoar is most pronounced at treeline, but it may be found in sheltered, north facing alpine areas.At the base of the snowpack is a crust that formed in late October. There have been no reports of reactivity on this layer; however, this layer may be reactive to human triggers in isolated locations such as steep, rocky terrain, with a shallow snowpack. Small avalanches may step-down to this crust resulting in large, destructive avalanchesSnowpack depths decrease dramatically with elevation.
Problems
Persistent Slabs
Be especially cautious with this buried weak layer in the Treeline elevation band, on large open slopes that have a deep enough snowpack to bury all the bushes and make the slope smooth. It may also be present in sheltered, N. facing alpine slopes.
Use small slopes with no consequence to test for the presence of the buried weak layer.Watch for signs of instability such as whumphing, cracking, and evidence of recent avalanches.Start in conservative terrain while you gather additional information about the snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 1st, 2018 2:00PM
