Avalanche Forecast
Issued: Mar 26th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Wind Slabs.
lbaker,
Avalanche Canada
In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Small isolated wind slabs may be found on exposed lee features in the alpine and below ridgetops. Carefully evaluate steep lines for wind slabs before committing to them.
Summary
Confidence
High
Avalanche Summary
No new avalanches were reported in the region on Saturday.
On Friday, a couple of cornice failures triggered loose dry avalanches up to size 2 on large alpine slopes.
A couple of deep persistent slab avalanches were reported this week. On Wednesday, a cornice fall entrained a mass of snow which then triggered a size 3 deep persistent slab avalanche. It occurred at 2350 m on a north east facing slope. On Tuesday, a size 2.5 deep persistent slab avalanche was reported in the South Chilcotin range, around 2200 m on a south-facing slope.
Snowpack Summary
10-20 cm of recent snow and light to moderate southwesterly wind may have formed small wind slabs on lee features at upper elevations.
Below the new snow is a melt freeze crust exists on all aspects at treeline and below, and on solar aspects to mountain top. On high north aspects is a mixture of decomposing dry snow and small surface hoar in isolated locations.
The mid-snowpack is generally strong but the lower snowpack is a different story.
A weak layer of sugary facets is still prominent at the base of the snowpack. Small surface avalanches and cornice falls are the most likely things to trigger this layer. However, there remains a significant concern for human triggering in rocky, shallow, or thin-to-thick snowpack areas at treeline and above.
Weather Summary
Sunday Night
Clear skies. Light southeast ridgetop wind. Temperatures at treeline reach a low of -8 C. Freezing levels drop to valley bottom.
Monday
Sunny with convective clouds bringing isolated localized flurries, trace accumulation. Light east ridgetop wind. Temperatures at treeline reach a high of -5 C. Freezing level 1400 m.
Tuesday
Sunny. Strong northeast ridgetop wind. Temperatures at treeline reach a high of -1 C. Freezing level 1500 m.
Wednesday
Mix of sun and cloud. Light northwest ridgetop wind. Temperatures at treeline reach a high of 0 C. Freezing level 1800 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Avoid exposure to slopes that have cornices overhead.
- Carefully evaluate steep lines for wind slabs.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Problems
Deep Persistent Slabs
A layer of weak facets sits near the base of the snowpack. This layer is most likely to be problematic in steep, wind affected terrain where the snowpack depth varies from thick to thin. Especially in the northern part of the region around the Chilcotins, Birkenhead, and Hurley.
Recent natural avalanche activity was observed on this layer, likely triggered by warm temperatures and strong sunshine heating the snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
10-20 cm of recent snow and light to moderate southwesterly wind may have formed small wind slabs on lee features at upper elevations.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 27th, 2023 4:00PM
