Avalanche Forecast
Issued: Feb 25th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
ahanna,
Avalanche Canada
Human triggering of storm slabs remains possible. Caution around wind loaded features and convexities in the alpine and upper treeline.
Summary
Confidence
High - The number, quality, or consistency of field observations is good, and supports our confidence.
Weather Forecast
Tuesday night: A trace of new snow. Moderate west wind. Freezing level 1000 m.
Wednesday: Cloudy. Moderate northwest wind. Freezing level 1500 m.
Thursday: Mix of sun and cloud. Moderate southwest wind. Freezing level 1700 m.
Friday: Mix of sun and cloud. Moderate southwest wind. Freezing level 2100 m.
Avalanche Summary
A skier triggered wind slab avalanche size 2 was reported on a wind loaded northeast aspect near ridgetop. A few small loose wet avalanches ran on steep solar features during clear periods Tuesday.
On Monday, numerous natural, explosive, skier triggered, and remotely triggered storm slab avalanches were observed size 1-2 on all aspects at alpine and upper treeline elevations.Â
A natural avalanche cycle occurred Sunday, consisting of size 1-1.5 loose dry and soft slab avalanches. Activity was observed on various aspects but was especially concentrated on southeast to southwest where they ran on the surface hoar/crust combo.Â
Snowpack Summary
15-30 cm of recent snow is settling over a layer of surface facets, surface hoar in sheltered shady aspects or sun crusts on solar aspects. In the alpine and exposed treeline, recent snow has been redistributed by strong southwest to northwest wind, loading deep deposits into lee features.
An older layer of surface hoar now sits 30-50 cm deep. This weak layer produced significant avalanche activity focused in the east of the region prior to the last storm. While it is likely bonding over time, there is uncertainty around remnant reactivity. The remainder of the snowpack is well settled.
Terrain and Travel
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
Problems
Storm Slabs
15-30 cm of recent snow sits over a layer of surface facets, surface hoar in sheltered shady aspects or sun crusts on solar aspects. Reactivity at this interface has persisted since the storm and it is expected to remain sensitive to human triggering. Storm slabs will be deepest and most reactive where wind has loaded lee terrain features in alpine and exposed treeline areas. Recent winds have varied in direction from south to northwest, wind loading on a variety of aspects.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
An older layer of surface hoar now sits 30-50 cm deep. This weak layer produced significant avalanche activity focused in the east of the region prior to the last storm. While it is likely bonding over time, there is uncertainty around remnant reactivity. It has not been active in the recent avalanche cycle. If it remains triggerable, it will require large loads.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 26th, 2020 5:00PM
