Avalanche Forecast
Issued: Mar 20th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
lbaker,
Avalanche Canada
Use caution around wind loaded terrain where windslab may be reactive to skier traffic.
Summary
Confidence
Avalanche Summary
On Sunday, several loose wet, size 2, avalanches were observed below treeline. A skier controlled, size 1, wind slab avalanche was reported at 1400 m on a northeast aspect.
On Saturday, a few natural wind slab avalanches were observed up to size 2 in the alpine. Numerous loose wet avalanches to size 2 were observed in steep, rocky solar terrain and on all aspects below treeline.
On Friday, a size 3, naturally triggered, deep persistent slab avalanche was reported in the Stikine area, on a south facing slope at 1300 m. This avalanche occurred on the basal facets, up to 250 cm deep, likely triggered by a combination of warm temperatures and sun effect.
Snowpack Summary
Variable winds have built wind slabs on exposed terrain features near ridge top. A melt freeze crust or moist snow exists on the surface below 1500 m and on solar slopes above.
A weak layer of surface hoar is found 10-25 cm down in sheltered terrain. On solar aspects, this layer appears as a melt-freeze crust.
The middle of the snowpack is strong and contains numerous hard crusts.
The lower snowpack is composed of weak basal facets. This layer has produced limited recent avalanche activity, however it can quickly become active again with any significant change to the snowpack, such as rapid loading (heavy snowfall or rain) or prolonged and extensive warming. Avoiding thin and rocky slopes is still recommended.
Weather Summary
Monday Night
Mainly clear with a few clouds. Moderate southeast winds at ridgetop. Treeline temperature -2°C. Freezing levels hover around 1200 m.
Tuesday
Mix of sun and cloud. Moderate southwest winds at ridgetop. Treeline temperature 0°C. Freezing levels 1500 m.
Wednesday
Mix of sun and cloud with isolated flurries, trace accumulation. Moderate southwest winds at ridgetop. Treeline temperature -3°C. Freezing levels 1200 m.
Thursday
Mix of sun and cloud with isolated flurries, trace accumulation. Strong southwest winds at ridgetop. Treeline temperature -2°C. Freezing levels 1300 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Be carefull around freshly wind loaded features.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Problems
Wind Slabs
Storm snow has been redistributed by switching winds into deeper deposits in exposed alpine and treeline features. A buried layer of surface hoar is increasing reactivity and propagation of wind slabs. Avoid sheltered and shaded slopes where surface hoar is more likely to be found.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Weak, sugary faceted grains exist near the base of the snowpack. Riders are most likely to trigger this layer on steep, rocky slopes where the snowpack is shallow. The likelihood of avalanche activity on this layer will increase during periods of rapid change to the snowpack, such as heavy snowfall, rain, or rapid warming. Cornices are also very large at this time of year and a cornice failure could trigger this layer.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 21st, 2023 4:00PM
