Avalanche danger ratings assume 15 cm, possibly up to 20 cm of new snow tonight until Wednesday morning.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
TUESDAY NIGHT: Light snowfalls with accumulations between 5 to 15 cm but higher amounts (up to 25cm) are possible with upslope winds. Alpine temperature low -9C. Light northeast winds. WEDNESDAY: Flurries are possible with upslope wind. Mix of sun and cloud. Alpine temperature reaching -6C. Light east ridgetop winds.THURSDAY: Mainly cloudy. Dry. Alpine temperature high of -9C. Light west winds.FRIDAY: Mix of sun and cloud. Alpine temperatures reaching -4C with a freezing level of 1600m. Light west winds.
Avalanche Summary
Small and isolated (size 1-1.5) wind slab avalanches were naturally and human triggered Monday on steep alpine features. Storm and wind slabs are likely to be develop on exposed terrain at treeline and alpine.
Snowpack Summary
With up to 20 cm snow and wind in the forecast, storm and wind slabs are likely to develop. This new snow will bury hard wind slabs and wind pressed snow in alpine terrain. Last months cold temperatures have transformed most of the snowpack into weaker faceted snow with few if any distinct layers. In deep snowpack areas, it is possible to find a slab sitting above a layer of facets and surface hoar that was buried in mid-January and is 30-60 cm deep. The layer is most prominent in the Elk Valley between 1600 m and 1900 m, but no recent avalanche activity has been reported on this layer.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.