Avalanche Forecast

Archived

Dec 4th, 2023–Dec 5th, 2023

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

North Columbia, South Columbia, Blue River, Esplanade, Jordan, North Monashee, North Selkirk, West Purcell, Badshot-Battle, Central Selkirk, Goat, Gold.

Snow and rain with a rising freezing level will create a natural avalanche cycle.

Seek out low-angle terrain free of buried surface hoar.

Confidence

Moderate

Avalanche Summary

Several size one to two natural and skier-triggered avalanches were reported in our region this past weekend. Many of these were remotely triggered and ran on the buried surface hoar layer. These avalanches occurred at treeline elevation and on all aspects.

This MIN from Saturday does a great job describing conditions and this one from Sunday shows how the buried surface hoar layer getting triggered and causing avalanches.

Snowpack Summary

Around 30 mm of precipitation falling as rain and/or snow will have been added to the snowpack by the end of the day Tuesday. This will add to the up to 40 cm of new snow from this weekend which covered a layer of large surface hoar. On steep south-facing slopes, this surface hoar sits on a thin sun crust. At higher elevations, the weekend's snow will have formed wind slabs on north and east-facing slopes.

The mid-pack is generally well-settled. Lower in the snowpack a crust with sugary facets beneath it can be found 20 cm off the ground.

Weather Summary

Monday Night

Cloudy, 20 to 30 cm accumulation mix of snow and rain highest amounts in the south, alpine winds south 20 to 30 km/h, freezing levels reaching 2500 m.

Tuesday

Cloudy, up to 15 cm accumulation mix of snow and rain in some areas, alpine winds southwest 25 to 35 km/h, freezing level 2000 to 2500 m.

Wednesday

Mostly cloudy, 10 to 20 cm accumulation mix of rain and snow, alpine winds southwest 15 to 25 km/h, freezing level down to 1500 m by end of the day.

Thursday

Cloudy with chance of sunny breaks, up to 15 cm accumulation focused in the southwest, alpine winds southwest 10 to 20 km/h, freezing level 1500 to 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Remote triggering is a concern, watch out for adjacent and overhead slopes.
Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Minimize exposure during periods of heavy loading from rain.
Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.

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.