Avalanche Forecast
Regions: South Rockies.
New snow (and maybe rain at lower elevations), gusty winds, and rising temperatures are priming the snowpack for a natural avalanche cycle. Hazard will rise through Friday, peaking later in the day.
Confidence
Moderate - Uncertainty is due to the track & intensity of the incoming weather system. We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.
Weather Forecast
Thursday Night: Snow and flurries, 5-15 cm. Alpine temperature -8 C. Southwest wind 20-35 gusting to 60 km/hr.
Friday: Snow, heavy at times 20-30 cm. Alpine temperature -3 C. Southwest wind 20-40 gusting to 65 km/hr. Freezing level rising to 1600 m.
Saturday: Continued snowfall, 15-30 cm. Alpine temperature -2 C. Southwest wind 50 gusting to 80 km/hr. Freezing level 1600 m.
Sunday: Flurries, up to 10 cm. Alpine temperature -5 C. West wind 20-30 gusting to 50 km/hr. Freezing level dropping to valley bottom.
Avalanche Summary
Explosives triggered 2 small (size 1) wind slabs on Wednesday. A few small (size 1) natural avalanches were noted around the Castle area on Tuesday and skiers reported fresh wind slabs cracking underfoot.
Snowpack Summary
Wind has scoured exposed terrain and formed wind slabs in the alpine, and around lee features and lower into start zones. Forecasted snowfall will cover a variable and wind-affected surface and is expected to build and develop reactive storm slabs.
The bottom half of the snowpack consists of crusts from November and October and basal facets. These persistent weak layers produced large avalanches over a week ago but have since gained strength. Overall, a shallow and variable snowpack is found around the region. Snowpack depths range between 50-100 cm around treeline and taper rapidly below.
Avalanche Problems
Storm Slabs
Rapid loading from snow and gusty winds will produce touchy and reactive storm slabs. The likelihood of triggering an avalanche will increase towards the end of the day as new snow accumulates and is redistributed by wind.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 1 - 2.5
Persistent Slabs
A generally weak and shallow snowpack persists in the region, with early season crusts and facets near the bottom. This layer my awaken as rapid loading from snow, wind, or smaller storm slab avalanches stresses deeper instabilities, a resulting in larger and more destructive avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 1.5 - 3