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Avalanche Forecast

Dec 18th, 2019–Dec 19th, 2019
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: South Rockies.

Triggering an avalanche is most likely in wind affected terrain and steep, rocky slopes.

Confidence

No Rating - Uncertainty is due to the limited number of field observations.

Weather Forecast

Wednesday Night: Mostly cloudy. Alpine temperature -10 C. Southwest wind 25-35 km/hr.

Thursday: Flurries, trace to 5 cm. Alpine temperature -6 C. Southwest wind 20-35 km/hr.

Friday: Snow, heavy at times 20-30 cm. Alpine temperature -3 C. Southwest wind 20-40 gusting to 80 km/hr. Freezing level rising to 1900 m.

Saturday: Continued flurries, 5-15 cm. Alpine temperature -2 C. Southwest wind 30 gusting to 75 km/hr. Freezing level 1600 m.

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.

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

Wind Slabs

Wind has redistributed recent snow, scouring exposed slopes and forming wind slabs around lee features.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 1.5

Persistent Slabs

The likelihood of triggering a large avalanche on one of the crusts and weak layers in the lower snowpack is gradually reducing, but the consequence of doing so is high.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1.5 - 2.5