Avalanche Forecast
Issued: Feb 13th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Persistent Slabs and Deep Persistent Slabs.
llarson,
Avalanche Canada
Recent snow will take some time to stabilize, avoid steep, open terrain and back off if you see evidence of nearby avalanches, or if you notice cracks appear in the snow surface or other signs of instability.
Summary
Confidence
Moderate
Avalanche Summary
Natural and human triggered wind slabs and storm slabs continue throughout the region. Avalanche activity last week on the deep persistent weak layer continues to remind us that these layers are taking time to heal and continue to require diligence.
Going forward storm and wind slabs developed with the most recent new snow and moderate to strong winds will take some time to bond to previous surfaces. Triggering these layers in the upper snow pack could step down to weak layers deeper in the snowpack.
Snowpack Summary
10 to 30 cm of new snow accumulated in the region over the past few days with the highest amounts in the north of the region. This new snow has been redistributed by moderate to strong southwest winds at upper elevations building wind slabs in lee features in open alpine and treeline terrain.
These new wind slabs will be forming over previous surfaces of soft snow in sheltered terrain and old wind slabs in open terrain and continue to build over a melt-freeze crust that extends up to 1800 m in the northern part of the region and up to 2000 m further south. Small facets may be found above the crust. This layer warrants close monitoring as we move through the period where a critical load and slab properties may develop over it.
Deeper in the snowpack two layers of surface hoar which formed in early January are now roughly 80 to 140 cm deep. Although snowpack tests are indicating strengthening here, these weak layers are still being watched closely by local operators and may be associated with recent isolated step-down avalanches.
Large and weak facets from November are near the base of the snowpack and although avalanche activity on this basal weakness has been on a bit of a decline, it still figures prominently in the assessments and terrain use (and avoidance) of professionals throughout the region.
Weather Summary
Monday night
Cloudy with easing but convective flurries, 2 to 5 cm of new snow, 5 to 10 km/h northwest winds, treeline temperatures around -10 °C.
Tuesday
A mix of sun and cloud with isolated flurries, 5 to 10 km/h west winds, treeline temperatures around -11 °C.
Wednesday
Mainly cloudy, 5 to 10 km/h southwest winds, trace accumulations, treeline temperatures -7 °C.
Thursday
Mainly cloudy, flurries 5 to 10 cm of accumualtion, 20 to 30 km/h winds, treeline temperatures -8 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Use careful route-finding and stick to moderate slope angles with low consequences.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
Problems
Storm Slabs
Continuing, convective snowfall and strong southwesterly winds are building storm slabs and wind slabs that will be reactive to natural and human triggers. Expect wind loaded spots to be particularly reactive.
Keep in mind that storm slabs have strong potential to step down to deeper weak layers, resulting in large and consequential avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Numerous problematic weak layers exist in the top meter of the snowpack. Recent large persistent slab avalanche observations are strong evidence that these layers are still an active concern in this region. Recent avalanches have been triggered by a mix of large loads like cornices but also remote triggers.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A layer of large and weak facets sits near the base of the snowpack. This layer continues on a sporadic basis to produce very large avalanches that can travel far. Riders are most likely to trigger an avalanche on this layer in steep, shallow terrain, or by triggering a smaller avalanche that could step down to this layer. Your best defence is to stay diligent in choosing low-consequence terrain away from overhead exposure.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 14th, 2023 4:00PM
