Avalanche Forecast
Issued: Mar 19th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
wlewis,
Avalanche Canada
Watch for reactive conditions on specific features. Buried weak layers are still a concern, as well as wind loading at higher elevations.
Minimize exposure to south facing slopes during strong sunshine, avalanche danger can rise rapidly.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast. Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.
Weather Forecast
SATURDAY NIGHT: 4-10 cm possible overnight. Freezing levels drop to valley bottom. Moderate southwest winds.
SUNDAY: A mix of sun and cloud with moderate southwest winds and possible afternoon flurries. Freezing levels reaching 1300 m. Alpine high of -2.
MONDAY: 5 cm possible overnight. Isolated flurries possible over the day with mostly cloudy skies. Freezing levels reaching 1800m, with strong westerly winds.Â
TUESDAY: Freezing levels remain high, reaching toward 3000 m. Up to 10 mm of rain is expected. Strong southwest winds. Alpine high of +8 expected.Â
Avalanche Summary
On Friday, several small wind slabs were observed to have been naturally triggered out of steep north facing terrain features.Â
Avalanche activity has been tapering off over the week, with a natural cycle observed last on Wednesday. Explosive control also produced size 3 storm snow avalanches. Reactivity now appears limited to wind loaded features.Â
Small loose wet avalanches were seen on all aspects below the freezing line the past 5 days, and on sun affected slopes at all elevations. Even short bursts of spring sunshine can have a significant effect on the snowpack.Â
Snowpack Summary
Up to 80 cm over recent storm snow sits over a weak surface hoar layer in sheltered terrain, and on a sun crust on south facing slopes. The surface hoar hasn't shown activity in avalanches observations since Wednesday, however snowpack tests still indicate it is weak and reactive. The most concern is in wind loaded features, of the Pine Pass and the Renshaw area.Â
At higher elevations consistent southwest winds are creating deeper deposits on north through east facing features. Below 1500 m, moist snow or a melt-freeze crust likely exists from recent rain and warm temperatures.
The mid and lower snowpack is generally well-settled and strong in most areas, with multiple crusts throughout.Â
Terrain and Travel
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Wind Slabs
Moderate southwest winds have formed wind slabs at higher elevations.
These slabs may be surprisingly deep and propagate widely where they are sitting on a weak layer of surface hoar or a sun crust.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Around 40 cm of recent snow sits over a weak layer of surface hoar on sheltered and shaded slopes. Wind loading has buried this layer up to 100 cm deep in some areas. Reactivity has been mostly reported on east-facing slopes, in southern areas.
A sun crust also sits on south facing slopes below the recent storm snow, and has the potential to be reactive to human triggers.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 20th, 2022 4:00PM
