Parks Canada conducted a heli-bombing mission on the Sunshine access road today and got minimal results. 8/18 shots triggered windslabs that were size 1 to small size 2.

Ski hills were reporting fewer results than expected but both were reporting touchy cornices with Sunshine triggering a size 2 with shoveling. Lake Louise patrollers triggered a couple size 1 windslabs in lee alpine terrain that failed ~ 50 cm deep but not on the first ski cut.

30-70 cm of recent snow with W-SW wind has formed windslabs. In sheltered areas below treeline, this new snow sits on a layer of surface hoar buried on Jan 3. This layer is spotty but is more prominent in western areas.

Warming temps on Jan 13th are causing moist surface snow to treeline.

50-90 cm overlies the Dec 15 melt-freeze crust, present to 1800-2000 m, and 100-200 cm over the November facet/crust interfaces. In thinner snowpack areas, facets are present at the base

A ridge of high pressure is building over the region bringing dry conditions for the foreseeable future. Overnight Tuesday, a warm layer of air will bring freezing levels quite high (~ 3000m), but cooling will start on Wednesday with more seasonal temperatures on Thursday and Friday. Winds will be moderate to strong from the West on Wednesday which may keep things cooler, but ease on Thursday.

On Monday, widespread natural avalanche activity up to (size 2) was reported. Numerous human-triggered (size 1-1.5) were also seen and failing in the recent storm snow. Wet loose avalanches were reported below 1700 m.

Natural avalanche activity is expected to continue with warm temperatures on Wednesday.

Rain and rising freezing levels have created wet snow surfaces up to 2100 m and higher. In the alpine, up to 90 cm of recent snow has been transported by strong south winds. In areas protected from the wind, a surface hoar layer buried in early January may be found down 100+ cm.

The prominent mid-December crust is now buried around 1.5 m deep, and is present up to 2300 m. Triggering this layer is considered unlikely, except with large loads like a cornice failure or in thin snowpack areas.

Tuesday Night
Mostly cloudy. 20 km/h southwest ridgetop wind. Treeline temperature 2 °C. Freezing level 3100 m.

Wednesday
Mix of sun and clouds. 30 km/h southwest ridgetop wind. Treeline temperature 3 °C. Freezing level 2900 m.

Thursday
Mix of sun and clouds. 40 km/h northwest ridgetop wind. Treeline temperature -4 °C. Freezing level 800 m. Possible alpine temperature inversion.

Friday
Sunny. 30 km/h northwest ridgetop wind. Treeline temperature -2 °C. Freezing level 800 m. Strong alpine temperature inversion.

More details can be found in the Mountain Weather Forecast.

Artillery control in Rogers Pass overnight produced many avalanches from sz 2.5 to 3.5. Natural avalanches before control commenced were running to valley bottom in the Tupper/Macdonald corridor. Natural avalanche activity has decreased with the storm passage.

Ski operations neighbouring Rogers Pass report storm slabs being triggered both naturally and by humans to sz 2.

To summarize the snowpack, we have a heavy, warm, widespread storm slab perched atop a well-settled mid to lower snowpack.

Deeper in the snowpack lingers the Jan 1 persistent weak layer (PWL), buried 90-130cm. The PWL varies in character depending on elevation and aspect. Treeline and below, the PWL is a layer of surface hoar in sheltered areas. Above Treeline and into the Alpine, the PWL is a crust on solar slopes.

The main storyline to follow Wed is the high freezing levels.

Tonight: Mainly cloudy. Alp low 0°C. Winds SW 25km/h. Freezing level (FZL) 1600m

Wed Mainly cloudy with sunny periods. Alp high 3°C with a weak inversion. Winds SW 30-40km/h. FZL 1600-2600m

Thurs Cloudy with sunny periods. Alp high -3°C. Winds NW 15-25km/h. FZL 1000m.

Fri Sunny, Alp high 0°C. Winds light to 20km/h. FZL 1600m. Alpine temp inversion.