Avalanche Forecast
Issued: Apr 7th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Wind Slabs and Deep Persistent Slabs.
lbaker,
Avalanche Canada
New snow and strong winds are building deep pockets of cohesive slab on north and east aspects at higher elevations. Dial back your terrain choices if you are finding more than 20 cm of new snow.
Summary
Confidence
Avalanche Summary
On Thursday, there were reports of several cornice triggered avalanches throughout the Monashees up to size 3. These avalanches did not step down to deeper weak layers.
On Wednesday, storm snow continued to be reactive to natural and human triggers. A few surprise skier triggered storm slab avalanches were reported up to size 2. Naturally triggered storm slab and wind slab avalanches were observed up to size 2.5. Many of these avalanches are reported to be failing on a surface hoar layer buried near the end of March or a crust on solar aspects. Avalanche activity has primarily been observed on north and east aspects from 1700 m to 2200 m. Reports indicate that the Selkirks seem to be the most reactive with rider remote-triggered slabs in the upper 50 cm of snow.
Snowpack Summary
10-15 cm of recent storm snow overlies 15-40 cm of settling snow. A widespread crust is found down 20-50 cm, except for on north-facing slopes at treeline and above, where it sits on old, faceted surfaces, and surface hoar in sheltered terrain. A surface hoar layer (down 60 cm) has recently been reactive to human triggering primarily in the Selkirks, especially on northeasterly slopes from 1700 m to 2100 m.
Strong southwest wind will build fresh wind slabs on leeward slopes and behind terrain features.
The mid-snowpack is generally strong but the lower snowpack is a different story. The November facets are still prominent at the base of the snowpack. This layer remains a concern in rocky, shallow, or thin to thick snowpack areas at treeline and above.
Weather Summary
Friday Night
Cloudy with flurries. 5 cm of new snow are expected for most areas of the region, with up to 15 cm in local areas around Revelstoke. Ridgetop wind 40 km/h from the southwest. Freezing levels remain at 1500 m.
Saturday
Mainly cloudy with isolated flurries, 1-3 cm accumulation. Ridgetop wind 30 km/h gusting to 50 km/h from the southwest. Freezing levels 1700 m.
Sunday
Mainly cloudy with isolated flurries, 3-5 cm accumulation. Ridgetop wind 70 km/h from the southwest. Freezing levels fluctuate between 1700 m and 2000 m.
Flurries continue through the night bringing 7-12 cm of new snow.
Monday
Cloudy with flurries bringing mixed precipitation, 15-30 mm expected. Ridgetop wind 50 km/h gusting to 80 km/h from the southwest. Freezing levels fluctuate between 1500 m and 2000 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Persistent Slabs
A weak layer from late March is found down 50 cm and is responsible for a number of recent human triggered and natural avalanches in the region. With incremental loading through the next few days watch for signs that this layer may be becoming more reactive in the terrain around you.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
New snow and strong southwest winds are building deep pockets of fresh wind slabs on leeward slopes. Look for signs of instability especially as you transition into wind affected terrain.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's depth.
Suspect terrain for human triggering includes steep, shallow, and rocky terrain where the snowpack transitions from thin to thick.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 8th, 2023 4:00PM
