Avalanche Forecast

Archived

Nov 30th, 2021–Dec 1st, 2021

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

South Rockies.

Avalanche danger will increase through the day Wednesday. Avoid all avalanche terrain including low elevation runout zones during this period of heavy loading from new snow, wind, and rain.

Confidence

High - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.

Weather Forecast

Tuesday night: Flurries, 3-8 cm. Strong southwest wind. Freezing level rising 2000 to 2400 m by morning.

Wednesday: 10-25 cm wet snow, rain below 2000 m. Strong southwest wind. Freezing level 2400 m.

Thursday: 5-10 cm overnight then clearing. Moderate westerly wind. Freezing level dropping 2000 to 1700 m.

Friday: Mostly sunny. Light wind. Freezing level valley bottom.

Avalanche Summary

We are expecting a widespread natural avalanche cycle to accompany Wednesday's storm.

Neighboring Kananaskis Country reported a widespread natural avalanche cycle up to size 3 running full path on Sunday as well as a few naturals up to size 2 on Monday. Several of these large avalanches stepped down to a buried crust.

Reports in the region remain limited. If you go out in the mountains, please share your observations and/or photos on the Mountain Information Network!

Snowpack Summary

Heavy amounts of wet snow in the alpine accumulate over wind pressed surfaces while rain soaks the snowpack treeline and below.

Two crusts are found in the snowpack: the mid-November rain crust buried 20-30 cm and reported up to 2100 m, and a crust from early November found at the bottom of the snowpack up to 2300 m, this crust is being to break down and facet. Heavy loading by the current storm will answer our questions about the potential for failure at this layer.

Snowpack depths range from 40-150 cm at treeline elevations. Higher elevations may hold a deeper snowpack, but also be more heavily impacted from recent winds. Snowpack depths decrease rapidly below 1900 m.

Early season hazards are very real right now, be wary of thin/shallow snowpacks, rocks, stumps, creeks, and other sharks hidden under fresh snow.

Terrain and Travel

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.