Avalanche Forecast
Issued: Jan 28th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Wind Slabs and Persistent Slabs.
wlewis,
Avalanche Canada
The snowpack is thin and weak, with several buried weak layers of concern. Find the newest blog here for managing this weak snowpack.
Small avalanches, even wind slabs, have the potential to trigger larger avalanches deeper in the snowpack. Continue to choose low consequence terrain, avoiding terrain features capable of producing large avalanches.
Summary
Confidence
Avalanche Summary
Numerous skier triggered and natural wind slabs were reported throughout the region on east facing slopes throughout the last three days.
A few notable avalanche occurred on Wednesday, where small wind slabs 'stepped down' to deeper weak layer causing large avalanches.
On Tuesday there was a report of a size 3.5 natural avalanche in the Dogtooth Range. This was likely a deep persistent avalanche with a wide propagation triggering near ridgetop at the upper end of treeline on an easterly aspect.
On Monday there was a size 3 skier triggered a deep persistent avalanche on an east aspect starting at 2300 m in the Terminator area in the Dogtooth Range. This MIN outlines the avalanche.
Snowpack Summary
Up to 10 cm of wind affected new snow has buried wind affected surfaces, a small layer of surface hoar and a sun crust.
The mid-snowpack contains a couple of layers of major concern. The first is down 30 to 50 cm and is a layer of surface hoar from early January. The second is a layer of surface hoar, facets, and crust created in December and found 40 to 60 cm down. The surface hoar is most prevalent in sheltered areas while crusts with faceted snow are more widespread.
The bottom of the snowpack is weak and faceted and contains a weak layer from late November. Thin snowpack areas where weak layers sit closer to the surface should still be treated as suspect.
The total depth of this weak and shallow snowpack ranges between 80 and 180 cm at treeline and is shallowest in the eastern part of our region.
Weather Summary
Saturday Night
Mostly clear skies overnight with trace accumulations possible. Moderate northeast winds. Freezing levels below valley bottom.
Sunday
Sunny with no snowfall expected. Moderate northerly winds continue, alpine high temperatures of -16°C.
Monday
Sunny with increasing afternoon cloud. Winds switch to moderate (gusting strong) westerlies. Alpine high of -16°C.
Tuesday
A mix of sun and cloud. Trace accumulations of snowfall. Moderate westerlies. Alpine high of -12°C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Deep Persistent Slabs
A weak layer near the base of the snowpack, buried in November, has been recently reactive in the Dogtooth Range and Western Purcells. Human and natural triggering of this layer remains possible, especially in shallow areas with variable snow depths. Avoid thin and rocky start zones and choose well supported terrain features. And check out the latest blog for how to manage this problem.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Pockets of wind slabs may be found at higher elevations. Recent winds have varied from east to west throughout the region - look for wind affected snow on all aspects as you approach or descend from ridgelines.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Several weak layers sit in the upper and mid snowpack at prime depth for human triggering. Avoid convex rolls in sheltered terrain where buried surface hoar may be present. Choose supported terrain features, and avoid large open slopes.
Smaller avalanches could create a "domino effect" and create large avalanches with wide propagation.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 29th, 2023 4:00PM
