Avalanche Forecast
Issued: Feb 23rd, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
JSmith,
Avalanche Canada
Touchy storm slabs are developing over a widespread layer of surface hoar at all elevations. Expect these slabs to be most reactive on wind affected slopes.
Summary
Confidence
Moderate - Uncertainty is due to field data and reports showing a wide variation in conditions throughout the region.
Weather Forecast
SUNDAY NIGHT: Cloudy with flurries; 3-5 cm, light to moderate west wind, alpine temperature -9 C, freezing level below valley bottom.
MONDAY: Mostly cloudy with possible flurries; 0-3 cm, light west wind, alpine temperature -5 C, freezing level 1000 m
TUESDAY: Mostly cloudy, light to moderate northwest wind, alpine temperature -5 C, freezing level 900 m.
WEDNESDAY: Mix of sun and cloud, light to moderate northwest wind, alpine temperature -3 C, freezing level rising to 1300 m.
Avalanche Summary
On Saturday the new snow was reported as being reactive to skier traffic as a very thin soft slab in wind affected terrain. These slabs will become increasingly touchy as the new snow stacks up and settles into a cohesive slab. There have been a few sporadic large avalanches over the past 10 days. Most recently, a large (size 3) deep persistent slab avalanche was remotely triggered last Sunday just outside the forecast region near Mt. Seven. Photos in the Mountain Information Network report show this avalanche was initiated by a skier causing a whumpf on a ridge that released a small wind slab on an east-facing alpine slope which then stepped down to the facets at the bottom of the snowpack.Â
Snowpack Summary
10-25 cm of recent snow has buried a widespread layer of surface hoar (size 5-15 mm.). This layer exists at all elevations. This same layer of surface hoar may be sitting on a thin sun crust on solar aspects which is a particularly nasty combination. The new snow will likely become increasingly reactive to human triggers as it stacks up and settles into a cohesive slab. The middle of the snowpack is strong, but the base of the snowpack contains basal facets that have resulted in sporadic, large deep persistent slab avalanches, especially in shallow rocky start zones.Â
Terrain and Travel
- Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
- Be alert to conditions that change with elevation and wind exposure.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Storm Slabs
10-25 cm of recent snow is sitting on top of a widespread layer of surface hoar at all elevations. On solar aspects the surface hoar is sitting on a crust, a particularly nasty combination.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Weak snow at the bottom of the snowpack continues to pose a deep persistent slab avalanche problem. The most recent activity has been focused around the Golden area, but steep, rocky, shallow terrain throughout the region should be treated with caution. Avoid big alpine slopes that are threatened by cornices overhead.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 24th, 2020 5:00PM
