Avalanche Forecast
Issued: Jan 21st, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Persistent Slabs and Wind Slabs.
rgoddard,
Avalanche Canada
A complex snowpack continues to produce large and destructive avalanches.
Use conservative terrain choices and have a 'plan B' to avoid areas with a thin snowpack.
Summary
Confidence
Moderate
Avalanche Summary
Since Thursday there have been many avalanches in our area that have reached up to size 3.5 (very large). They have been triggered naturally but also with explosives and ski cuts. Many of these avalanches have been from storm slabs, wind slabs, as well as persistent and deep persistent slabs.
The varied size and characteristics of recent avalanches have been due to the complexity of the snowpack. These instabilities will remain with us for the foreseeable future and use of caution when traveling through the backcountry is advised.
Snowpack Summary
Recent storm snow, 15 to 25 cm, can be found in sheltered areas, while open terrain has been wind affected. The recent snow overlies a mid-January interface that includes small surface hoar all the way into the alpine in some parts of the region as well as a rain crust, that reaches up to 2000 m, which can be found in most but not all areas of the region.
There are two additional weak layers in the top metre of the snowpack. The first is down 30 to 50 cm and is a layer of surface hoar from early January. The second is a layer of surface hoar, facets, and a crust from December, down 40 to 90 cm. The surface hoar is most prevalent in sheltered areas while crusts and any associated faceted snow are more widespread.
The bottom of the snowpack contains yet more weak, faceted snow. Large avalanches continue to be produced from this weak snow and will likely persist for the time being.
All of these interfaces are at their shallowest in the east of the region and all of them have produced avalanches recently.
In general, the snowpack is shallow and weak throughout our region with 80 to 180 cm sitting on the ground at treeline and alpine.
Weather Summary
Saturday Night
Increasing cloud, up to 5 cm accumulation in western sections, 8 to 20 km/h southwest wind, alpine temperatures -10 C.
Sunday
Sunny with cloudy periods, trace accumulation, 25 km/h northwest winds, alpine high of -10 C.
Monday
Mostly sunny, trace accumulation, 34 km/h southwest wind, alpine temperatures -10 C.
Tuesday
A mix of sun and cloud, no accumulation, 20 km/h west wind, alpine temperatures -8 C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Deep Persistent Slabs
A weak layer near the base of the snowpack, buried in November, continues to produce large, destructive avalanches with heavy loads. Human triggering of this layer remains possible as well, especially in shallow areas with variable snow depths.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
There are two weak layers in the top meter of the snowpack that continue to produce human-triggered avalanches. The first is a layer of surface hoar down 30 to 40 cm buried in early January. The second is a layer of surface hoar, facets and/or a crust from December. This layer can be found down 40 to 70 cm.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Shifting winds have been acting on 15 to 25 cm of recent snow, likely forming wind slabs on a wide range of aspects in exposed areas. Southwest winds will be the driver on Saturday.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 22nd, 2023 4:00PM
