Avalanche Forecast
Issued: Mar 18th, 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
Buried weak layers are keeping danger ratings elevated. Watch for signs of instability like whumpfing, natural avalanches and cracking.
Watch for fresh wind loading at higher elevations from southwest winds.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
FRIDAY NIGHT: Cloudy, isolated flurries bring up to 5 cm overnight. Freezing levels drop to 500 m. Moderate southwesterly winds.Â
SATURDAY: Partly cloudy, 3-10 cm over the day. Freezing levels reach 1500 m. Moderate southerly winds turn west in the afternoon. Alpine high of -1.
SUNDAY: Around 5 cm possible overnight. A mix of sun and cloud with moderate southwest winds. Freezing levels reaching 1500 m. Alpine high of -2.
MONDAY: Isolated flurries possible with mostly cloudy skies. Freezing levels reaching 1800m, with strong westerly winds.Â
Avalanche Summary
On Thursday, several wind slabs to size 1.5 were observed in north east facing alpine features, lee to the southwest winds. Check out this MIN report for a good description of current snowpack conditions, they noted shooting cracks and signs of instability on their trip.
Small loose wet avalanches were seen on all aspects below the freezing line, and on sun affected slopes at all elevations. Even short bursts of spring sunshine can have a significant effect on the snowpack.Â
On Wednesday, explosive control south of Renshaw produced avalanches up to size 3 within the recent storm snow. Natural activity was observed in specific wind loaded features around ridgelines to size 1.5.
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 has shown recent reactivity, with the most concern in Pine Pass and the Renshaw area.Â
At higher elevations consistent southwest winds are creating deeper deposits on north through east facing features. Below 1300 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 the Pine Pass and Renshaw 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 19th, 2022 4:00PM
