Avalanche Forecast
Issued: Dec 17th, 2021 4:05PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Persistent Slabs and Loose Dry.
jonas hoke,
The incoming storm will reach it's peak Saturday afternoon, expect a natural avalanche cycle around that time.
Uncertainty surrounds the effect of this storm on the Dec. 1st persist weak layer, give large avalanche terrain a miss until this plays out.
Summary
Weather Forecast
A warm front will hit our area early Saturday morning, bringing snowfall, warming temps, and strong winds.
Tonight: Clear periods. Alpine low -19*C. Light S ridge winds
Saturday: Snow (22cm). High -9*C. Strong SW winds
Sunday: Sunny periods, a few flurries. Low -15*C, High -9*C. Light N winds
Monday: Mostly sunny. Low -22*C, High -13*C. Light SW wind
Snowpack Summary
Incoming new snow will fall on previously facetted low density snow. The Dec 1 crust is ~10cm thick, buried a ranging depth of 50-100cm, and can be found up to 2300m. Signs of facetting have been found above and below this crust, particularly in shallow snowpack areas at and just below treeline.
Avalanche Summary
A few small-large natural avalanches where observed in the highway corridor on Friday, these were failing as loose dry and thin soft slab avalanches.
Snowpack tests continue to give sporadic sudden results on the Dec. 1st crust, particularly in shallower snowpack areas at Treeline.
Confidence
Problems
Storm Slabs
Incoming new snow will not likely bond well to previously facetted surfaces. Warmer temps and strong winds will cause rapid slab formation.
- Minimize overhead exposure during periods of heavy loading from new snow, wind.
- Use caution in lee areas in the alpine and treeline. Storm snow is forming touchy slabs.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
The Dec 1st crust is buried by 40-100 cm of snow. Be especially cautious in thinner snowpack areas, where it is more likely to be reactive. The crust is most reactive at tree line, but it is present below tree line and in the lower alpine.
- Avoid steep convexities or areas with a thin or variable snowpack.
- If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Loose Dry
Expect loose dry avalanches in steep terrain.
- Use caution above cliffs and terrain traps where small slab avalanches may have severe consequences.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 18th, 2021 4:00PM
