Archived

Avalanche Forecast

Dec 12th, 2019–Dec 13th, 2019

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

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

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

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

Regions: South Rockies.

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

Confidence

No Rating - Uncertainty is due to extremely variable snowpack conditions reported through the region.

Weather Forecast

THURSDAY NIGHT: Scattered flurries with 5-10 cm of new snow, 40-50 km/h wind from the west, alpine temperatures drop to -10 C.

FRIDAY: Isolated flurries with up to 5 cm of new snow, 30 km/h wind from the west, alpine high temperatures around -6 C.

SATURDAY: Mix of sun and cloud, light wind from the northwest, alpine high temperatures around -8 C.

SUNDAY: Sunny with some clouds, 30 km/h wind from the northwest, alpine high temperatures around -10 C.

Avalanche Summary

Recent avalanche activity is limited to a few wind slab avalanches (size 1-2) triggered with explosives. Avalanche activity has quieted down since last weekend, when several large persistent slab avalanches (size 2-3) were reported at treeline and alpine elevations. Most of them were also triggered with explosives, but one was remotely triggered as a person walked on low angle terrain above the slope. These avalanches have run on buried crusts and weak layers ranging from 40-100 cm deep.

Snowpack Summary

New snow and wind has likely formed fresh wind slabs at upper elevations. In sheltered areas 20-30 cm of snow from last weekend is gradually settling. Weak snow can be found 30-80 cm deep around crust layers that formed in November and October. These persistent weak layers produced large avalanches last weekend but have gained strength since then. Snowpack depths range between 50-100 cm at higher elevations and taper rapidly below treeline.