Avalanche Forecast

Saturday night: Low of -11 at 1700m in the north and -5 in the south. Light to moderate northwest winds and no new snow expected.

Sunday: mix of sun and clouds with freezing levels rising to 1500m in the north and 2200m in the south. Light northwest winds shifting to west in the afternoon.

Monday: light precipitation bringing trace amounts of snow. Light southwest winds in the morning shifting to moderate northwest in the afternoon. A high of -3 at 1700m.

Tuesday: a mix of sun and cloud with a high of -2 at 1700m. Light to moderate northwest winds.

On Saturday several skier triggered wet loose avalanches to size 1.5 were observed on steep sun exposed terrain at treeline.

On Friday numerous loose wet avalanches up to size 1.5 were observed on solar aspects below treeline. A natural cornice fall and a natural icefall also occured, these occured on east aspects.

On Thursday loose wet avalanches were observed up to size 1.5 on solar aspects at lower elevations. One size 2 wind slab avalanche was triggered by explosives on a morainal feature at 2200m.

On Wednesday in the southern part of the forecast region a skier triggered a size 2 wind slab avalanche in a steep rocky feature at 2600m on a east aspect. This avalanche ran on the mid January crust.

On Tuesday several small cornice falls were observed triggering slab avalanches up to size 2 in lee and cross loaded features at treeline and above. A skier triggered a size 1.5 slab avalanche on a steep treeline feature on a south aspect, this avalanche ran on the late January layer.

This MIN post from the Dogtooth shows the type of open slopes where the buried surface hoar may be reactive at lower elevations.

A melt-freeze crust is expected on solar aspects into the alpine and on all aspects below treeline. This crust will likely break down and become moist as the freezing level rises and the sun comes out. Previous strong wind from the southwest through northwest have formed wind slabs at higher elevations and over hanging cornices on some ridge features.

The January 30 interface is now typically down 20-50cm and consists of a melt-freeze crust on solar aspects extending into the alpine, surface hoar in sheltered areas at and below treeline, and small facets in some areas.

Several old surface hoar layers are now buried in the upper snowpack 40-120cm deep. 

The early December crust/facet layer of concern sits around 80 cm deep in the eastern Purcells and shallow terrain, and up to 150 cm in the west. This layer produced numerous large avalanches in January but is now considered dormant. See this forecaster blog on how to manage this layer as it may come into play again later this season. 

• Minimize exposure to sun-exposed slopes when the solar radiation is strong.
• Cornices become weak with daytime heating or solar exposure.
• Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
• Be careful as you transition into wind affected terrain.