Storm cycle in effect. The combination of new snow, strong winds, and warm temperatures is promoting a natural avalanche cycle. Local ski hills reported continued loading on exposed terrain at alpine and treeline elevations throughout Monday. We expect natural avalanche activity to peak on Tuesday.

30-60 cm of recent storm 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, but this layer is not widespread and more prominent on Hwy93S and in Yoho.

There is 50-90 cm over 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 westerly flow will bring more precipitation with accumulation values between 15 to 50 cm, and rain at lower elevations. Precipitation to taper on Tuesday, with a clearing trend developing in the afternoon. Temperatures will continue to rise through Wednesday, with freezing levels reaching 2000 to 2500 m at the peak of the warmth. Winds will remain strong over the next few days and begin to taper on Thursday.

On Sunday a few small storm slab avalanches where reported, failing on a the surface hoar layer. These avalanches were in areas protected from the wind, such as small opening in areas of dense trees.

Last week, large natural persistent slab avalanches were widespread size 2 to 3.5.

Up to 90 cm of recent snow has been transported by strong south winds. In areas protected from the wind, a surface hoar layer can 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 or in thin snowpack areas.

Monday Night
Cloudy. 15 to 25 cm of snow. 40 km/h west ridgetop wind. Treeline temperature -2 °C. Freezing level 1500 m.

Tuesday
Cloudy. 1 to 2 mm of precipitation as snow or rain at treeline. 30 km/h west ridgetop wind. Treeline temperature -1 °C. Freezing level 1900 m.

Wednesday
Mostly sunny. 40 km/h southwest ridgetop wind. Treeline temperature 2 °C. Freezing level 2600 m.

Thursday
Mostly sunny. 30 km/h northwest ridgetop wind. Treeline temperature -3 °C. Freezing level 800 m.

More details can be found in the Mountain Weather Forecast.

With the ongoing storm, a natural avalanche cycle to size 3.5 is currently underway in Rogers Pass and will continue into Tuesday.

Recent MIN reports show a number of avalanche occurrences. A group heading to the Asulkan hut triggered an avalanche that involved 3 people, one who was mostly buried. Read about that here.

Neighboring operations are reporting both reactive windslab and persistent slab problems that are producing avalanches up to size 3.5!

Warm temps and heavy snowfall has created a widespread storm slab. This is perched atop wind slabs in the Alpine and exposed Treeline areas.

Below this week's storm snow, a layer of surface hoar is buried 80-120cm deep in sheltered areas at treeline & below. On solar slopes, the storm snow sits over a crust which is also acting as failure plan for human triggered avalanches.

Heavy snowfall continues Monday night while the temps rise into Tuesday.

Tonight: Snow, 20-25cm. Alp Low -3°C. Winds SW 30 km/h gusting to 45. Freezing level (FZL) 1500m

Tues Flurries, 5-10cm. Alp high 1°C. Winds SW 30-45km/h. FZL 2500m

Wed Mainly cloudy. Alp high 4°C with a weak inversion. Winds SW 30-40km/h. FZL 1900m

Thurs Cloudy with sunny periods. Alp high -1°C. Winds NW 15km/h. FZL 900m.