Strong solar radiation and warm temperatures will weaken cornices and the snowpack. Avoid overhead hazard, especially in the afternoon. The danger rating is for the hottest time of the day. Check out this blog on warming and how to stay safe.
Summary
Confidence
Weather Forecast
A ridge of high pressure over the province continues to bring sunny, dry weather. Freezing levels are forecast to steadily rise through the week.
Tuesday night: Clear moderate northeast wind, alpine low -12 C, freezing level at valley bottom except for the west of the region where it will rise to 2200 m.
Wednesday: Sunny, moderate northeast wind, alpine high +5 C, freezing level 2500 m.
Thursday: Sunny, moderate east wind, alpine high +9 C, freezing level 2700 m.
Friday: Sunny, light northeast wind, alpine high +10 C, freezing level 3000 m.
Avalanche Summary
On Monday a few small wet loose avalanches were reported on steep south facing slopes.
Wind slabs have shown quite limited reactivity over the weekend, a few natural and ski cut size 1-1.5 were observed on Saturday. On Friday, most activity in the recent snow has been limited to size 1 loose snow avalanches. One size 2 was reported.
A couple of natural cornice failures size 2.5 observed on Sunday did not trigger slabs on slopes below.
Neighboring Glacier National Park reported a few very large (size 3-4) glide slab releases on Thursday. Glide slabs are hard to predict and can release at any time so it is important to avoid slopes with glide cracks.
Snowpack Summary
The snow surface consists of a melt-freeze crust on solar aspects. Dry snow can still be found on northerly aspects at treeline and in the alpine. The 20-30 cm of recent snow sits on a series of melt-freeze crusts on all aspects below 1900 m and southerly aspects to mountain top. On North aspects in the alpine, the recent snow sits on dry wintery snow surfaces and possibly surface hoar on wind-sheltered slopes.
The recent warm weather is expected to have helped old persistent weak layers heal, including a few crusts buried over the last month as well as a facet layer 150 cm deep from the mid-February cold snap. With each day of warm weather the likelihood of persistent slab avalanches might increase slightly.
Terrain and Travel
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
- Loose avalanches may start small but they can grow and push you into dangerous terrain.
- Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.
Problems
Cornices
Cornices are large and will become more fragile with rising temperatures and sun exposure. Many natural cornice failures were reported recently. Cornice falls are dangerous on their own and they can trigger slabs on slopes below.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Loose Wet
Surface snow can quickly lose cohesion and become unstable with strong solar radiation and warm temperatures. Avoid exposing yourself to sunny slopes, especially in the afternoon.
Aspects: South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Apr 14th, 2021 4:00PM
