Avalanche Forecast
Issued: Mar 23rd, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs.
wlewis,
Avalanche Canada
Cooler temperatures and cloudy skies should reduce avalanche activity. Alter your travel plans if you see periods of strong sunshine or rapidly warming temperatures, deep persistent avalanches have been recently observed.
Avoid thin and rocky terrain features where weak layers sit closer to the surface.
Summary
Confidence
High
Avalanche Summary
Significant natural avalanche activity has been observed on the deep persistent weak layer of facets at the base of the snowpack this week, likely triggered by strong solar input (sunshine) and warm temperatures. Cooler temperatures and cloud cover should reduce the likelihood of continued activity.
Yesterday a cornice fall triggered a size 3 avalanche at 2350m on a north east facing slope. A size 2 avalanche was reported on a southwest facing slope at 1950 m.
A size 2.5 deep persistent slab avalanche was reported Tuesday in the South Chilcotin range, around 2200 m on a south-facing slope.
Wet-loose avalanches up to size 1.5 have been reported daily during the recent warm, sunny weather. Larger avalanches have been produced by isolated terrain features like large, smooth rock slabs.
Snowpack Summary
A melt freeze crust exists on all aspects at treeline and below, and on solar aspects to mountain top. This crust is unlikely to breakdown with cooler temperatures and cloud cover forecast. The surface snow in northerly-facing alpine terrain remains generally cold and dry.
Convective conditions have the potential to deliver light accumulations of snowfall to isolated areas, which are challenging to predict. Moderate southwest winds may build small wind slabs on north and east facing terrain in these areas.
The middle of the snowpack is generally settled and bonding, with no current concerns. At the base of the snowpack is a layer of weak and sugary facets exists, reportedly up to 50 cm thick. This layer continues to be a concern especially during periods of change (rapid warming, heavy snowfall or cornice falls), producing irregular avalanche activity.
Weather Summary
Thursday Night
Mostly cloudy with overnight flurries. Moderate southerly winds. Freezing levels drop to near 500 m.
Friday
Mostly cloudy with possible flurries. Winds ease to light southwesterlies. Freezing levels reach 1200 m.
Saturday
Mostly cloudy. Light southwesterlies. Freezing levels reach 1200 m.
Sunday
A mix of sun and cloud with light easterly winds. Freezing levels around 1300 m. Flurries possible.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- A crust on the surface will help bind the snow together, but may make for tough travel conditions.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
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
Valid until: Mar 24th, 2023 4:00PM
