Avalanche Forecast
Issued: Feb 4th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
ghelgeson,
Avalanche Canada
Conservative terrain choices are critical right now. Large avalanches remain sensitive to human triggering and many have run in terrain you wouldn't consider "scary." Take a look through recent MIN posts for an idea of what's been happening.
Summary
Confidence
Weather Forecast
We’re looking at dribs and drabs of snow through the weekend before the pattern gives way to a ridge of high pressure on Monday.
THURSDAY NIGHT: Freezing level at valley bottom, light northwest wind with potentially stronger wind at ridge top, 2 to 6 cm of snow possible.
FRIDAY: Overcast, freezing level at valley bottom, light west wind at most elevations with strong northwest wind at ridge top, 1 to 5 cm of snow possible.
SATURDAY: Broken cloud cover, freezing level at valley bottom, light southwest wind at most elevations with strong northwest wind at ridge top, 4 to 10 cm of snow possible.
SUNDAY: Scattered cloud cover, freezing level at valley bottom, light west wind at most elevations with moderate northwest wind at the highest ridge tops, trace of snow possible.
Avalanche Summary
Wednesday delivered quite a bit of human triggered avalanche activity to size 2. While all aspects were involved, the bulk of the activity was on northwest, north and northeast facing slopes between 1900 and 2300 m. This MIN from the RMR backcountry is a great representation of the widespread activity. A notable size 3 avalanche was reported from the southeast corner of the region near Balfour, BC. The skier triggered avalanche was on a north/northwest facing slope around 2000 m, it propagated across an entire drainage and may be wider than one kilometre. It likely ran on the early January surface hoar.
On Tuesday, numerous natural storm slabs up to size 3 and skier triggered up to size 2.5 were reported on all aspects/elevations throughout the region. These storm slabs were primarily running on a weak layer of surface hoar down 50-80 cm. Additionally, a notable size 3.5 naturally triggered persistent slab avalanche failing on a rain crust buried in early January was reported near Trout Lake.
Snowpack Summary
60 to 100 cm of recent snow, warm temperatures, and moderate southerly winds have formed touchy storm slabs. These storm slabs are sitting on multiple weak layers of surface hoar which have potential to surprise backcountry users by how easily they may be triggered and how wide the slabs propagate across slopes. The first sits below the recent snow and the second is around 10-30 cm. deeper.
The lower snowpack is generally well settled and strong in most areas.
Terrain and Travel
- Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
- Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
- Be careful as you transition into wind affected terrain.
Problems
Storm Slabs
Storm slabs may be surprisingly large and easy to trigger due to the presence of buried weak layers of surface hoar.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Touchy storm slabs have recently overloaded a weak layer of surface hoar buried late January. Human triggering of this layer will remain likely where it is well preserved. The most likely places being large, open, convex slopes at treeline and below.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Feb 5th, 2021 4:00PM
