Avalanche Forecast
Issued: Mar 2nd, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet, Cornices and Wind Slabs.
ahanna,
Avalanche Canada
The CONSIDERABLE rating reflects the potential for wet snow avalanches in the south of the region, where above freezing temperatures are forecast up to 2000m Wednesday. Further north, where freezing levels remain around 1500m, avalanche danger is MODERATE.
Summary
Confidence
Weather Forecast
Tuesday night: Partly cloudy. Moderate southerly . Freezing level 1000 to 500 m. Southwesterly wind light below 2000 m, moderate 2000-2500 m, strong above.
Wednesday: Mix of sun and cloud. Moderate southerly wind increasing to strong above 2000 m. Freezing level rising to 1500 m in the north and 2000 m in the south.
Thursday: Mix of sun and cloud. Moderate to strong southerly winds. Freezing level 1700 m in the north and 2200 m in the south.
Friday: Mix of sun and cloud. Moderate to strong southerly winds. Freezing level 1500 m.
Avalanche Summary
Natural glide slab avalanches size 2-2.5 were observed out of steep north facing paths below treeline in the Coquihalla area Monday. Glide slabs are notoriously difficult to forecast but with the warming trend ahead, we may see an uptick in activity. Glide slabs are most likely in areas of smooth ground cover such as rock slabs at lower elevations experiencing prolonged warm temperatures with limited overnight refreeze. These avalanches will be large, involving the full depth of the snowpack. Carefully consider your access/egress routes where they cross under large paths.
Over the weekend, the Coquihalla area saw heavy skier traffic. While most reports described good ski quality in the trees, one MIN reported a skier triggered wind slab on a northeast aspect around treeline.
On Sunday, a size 1.5 skier accidental was reported on a northwest aspect in the alpine near Duffey Lake. The slab is thought to have failed on a thin layer of underlying facets over the firm bed surface of old, previously wind-stiffened snow.
Snowpack Summary
Upper elevations are wind affected throughout the region.
- In the Coquihalla area, the snowpack is generally well consolidated with no concerns of buried weak layers.
- In the north of the region, 15-30 cm of snow sits over a widespread layer of facets and isolated crusts. This interface is of most concern in areas where a thin layer of facets separates recent wind slab (above) and old buried hard slabs (below) which can act as a bed surface.
- A persistent weak layer composed of a crust, facets or surface hoar depending on elevation/aspect is now down 70-120 cm. This layer, buried in late January, continues to be noted in snowpack tests with mixed results. There have been no recent avalanches reported on this layer. Large triggers, such as an avalanche in motion, cornice fall, or intense loading from snow/ wind and/or a rapid rise in temperature can awaken these deeper weak layers. The lower snowpack is well settled and strong in most areas.
Terrain and Travel
- Back off slopes as the surface becomes moist or wet with rising temperatures.
- A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
- Avoid lingering or regrouping in runout zones.
- Cornices become weak with daytime heating or solar exposure.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
Problems
Loose Wet
A wet loose avalanche problem exists in the south of the region, where sunny skies are coupled with freezing levels reaching 2000 m Wednesday. Loose wet avalanches are most likely on steep sun exposed slopes and at elevations experiencing above freezing temperatures for the first time.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Cornices are large, looming, and can become weak with rapid warming. Avoid exposure to slopes with cornices overhead and stay well back of them when travelling on ridgetop.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine.
Likelihood
Expected Size
Wind Slabs
Older wind slabs exist on a variety of aspects and may remain reactive where they sit over a thin layer of facets on a hard bed surface.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 3rd, 2021 4:00PM
