Avalanche Forecast
Regions: South Rockies.
Don't let your guard down during clear skies; recently formed slabs and a buried weak layer can still be triggered by riders.
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
TUESDAY NIGHT: Partly cloudy, 20 km/h northwest wind, alpine temperature -12 C.
WEDNESDAY: Clear skies, 20 km/h west wind, alpine temperature -11 C.
THURSDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 30 to 60 km/h southwest wind, alpine temperature -9 C.
FRIDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 30 to 40 km/h west wind, alpine temperature -9 C.
Avalanche Summary
We've only received a few reports of storm slab avalanches around 30 cm deep on Monday, localized in the southwest of the region. However, visibility was poor, so the extent of activity likely couldn't be seen.
Looking towards Wednesday, natural avalanche activity is expected to diminish, except perhaps on steep southerly slopes from solar warming. Human triggering of storm, wind, and persistent slabs will remain possible.
Snowpack Summary
Anywhere from 10 to 50 cm of snow fell on Monday and Tuesday, with the most in the south and west of the region near the divide. In areas where more snow fell, storm slabs may remain reactive to human traffic, particularly where it overlies sugary faceted grains from recent cold air. The wind was howling from the south during the storm, which formed wind slabs in exposed terrain.
Around 50 to 80 cm deep, a weak layer of surface hoar may be found in sheltered terrain or otherwise faceted grains and/or a hard melt-freeze crust. This layer has so far shown to be most problematic around the Elk Valley, but you may find it elsewhere.
Weak faceted grains and a decomposing melt-freeze crust are likely found near the base of the snowpack. There have not been recent avalanche observations on this layer, but steep and rocky slopes as well as shallow snowpack areas should be approached with caution.
Terrain and Travel
- Choose conservative terrain and watch for clues of instability.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Avalanche Problems
Storm Slabs
Storm slabs are likely most prevalent in the south and west of the region near the divide, where the most snow has accumulated. Use added caution anywhere you find more than 20 cm of soft snow. Otherwise, wind slab avalanches are expected to be widespread and across the entirety of the region from strong southwest wind pushing the 10 to 50 cm of snow into lee terrain features. Use particular caution on sun-exposed slopes as well as in lee terrain features near ridges. Conservative terrain travel is recommended until the snow has some time to bond to the snowpack.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible - Likely
Expected Size: 1 - 2.5
Persistent Slabs
Around 50 to 80 cm of snow overlies a buried weak layer of surface hoar, faceted grains, and/or a melt-freeze crust, depending on elevation and aspect. Reports to date suggest the Elk Valley being the most problematic area, but don't let your guard down elsewhere. Avalanches have occurred on surprisingly shallow slope angles.
Aspects: All aspects.
Elevations: Treeline.
Likelihood: Possible
Expected Size: 1.5 - 2.5