North Columbia

Storm slab size and reactivity to triggers will increase as the new snow or rain accumulates

Fall back to simple terrain as conditions worsen

Moderate

• Forecast snowfall amounts are uncertain.
• Uncertainty is due to the limited number of field observations.

On Thursday

• A naturally triggered size 2.5 avalanche was observed in the Northern Cariboos.

On Wednesday

• Numerous loose dry sluffs out of extreme terrain were observed southwest of Valemount. They were up to size 2 and likely triggered by wind or sun.

• Looking forward: The likelihood of both human and natural-triggered avalanches is expected to rise as storm snow accumulates on Sunday.

15 to 40 cm has recently fallen in the region. An additional 5 to 20 cm is expected by Saturday afternoon. There is a chance of rain below 1400 m, which could cause wet loose avalanches.

Combined with forecast strong southerly winds, the new snow will continue building reactive storm slabs. These slabs will likely be deeper and more reactive on wind-loaded lee slopes near ridgetops.

The prominent mid-December crust is buried up to 110 cm deep and extends to 2200 m. Triggering the crust is considered unlikely, except with large loads or in thin snowpack areas.

Saturday Night
Cloudy. 4 to 10 cm of snow. 35 km/h south ridgetop wind. Treeline temperature -4 °C. Freezing level 1000 m.

Sunday
Cloudy. 2 to 10 cm of snow. 50 km/h south ridgetop wind. Treeline temperature -3 °C. Freezing level 1400 m.

Monday
Mix of sun and clouds. 4 to 5 cm of snow. 30 km/h southwest ridgetop wind. Treeline temperature -9 °C.

Tuesday
Cloudy. 5 to 15 cm of snow. 40 km/h southwest ridgetop wind. Treeline temperature -8 °C.

More details can be found in the Mountain Weather Forecast.

• Use increased caution at all elevations. Storm snow is forming touchy slabs.
• Watch for rapidly changing conditions during periods of heavy loading from new snow, wind, or rain.
• As the storm slab problem worsens, the easy solution is to choose more conservative terrain.