Avalanche Forecast

Many more avalanches were triggered by riders and explosives on the weak layers described in the Snowpack Summary on Monday. The avalanches occurred in alpine and treeline terrain and on all aspects. This adds to many other notable avalanches in the Purcells, such as this one near Golden). Triggering large persistent slab avalanches will likely remain a concern for a while within this region.

Roughly 40 cm of recent snow has settled into a slab that overlies weak faceted grains. The snow is also stressing buried weak layers, including:

• A surface hoar layer buried in mid-December that is 40 to 60 cm deep

• Weak faceted snow and decomposing crusts near the bottom of the snowpack, ranging from 70 to 150 cm deep.

These layers have produced large avalanches over the past week and need more time to strengthen.

Monday Night

Clear with no precipitation, 10 km/h south wind, light inversion, treeline temperature -6 °C.

Tuesday

Sunny with no precipitation, 10 km/h southwest wind, treeline temperature -8 °C.

Mostly sunny with a trace of precipitation, 10 km/h northwest wind, treeline temperature -12 °C.

Mix of sun and cloud with a trace of snow, 20 to 30 km/h southeast wind, treeline temperature -10 °C.

More details can be found in the Mountain Weather Forecast.

• Choose conservative terrain and watch for clues of instability.
• Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
• Remote triggering is a concern, watch out for adjacent and overhead slopes.
• Back off if you encounter whumpfing, hollow sounds, or shooting cracks.