Avalanche Forecast

Archived

Jan 27th, 2024–Jan 28th, 2024

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

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 possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Kootenay Boundary, Lizard-Flathead, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, Ymir, Flathead, Crawford, Moyie, St. Mary, Kokanee, Retallack, Valhalla.

There is high variability with the amount of precipitation and whether it'll fall as rain or snow.

Rain on snow will rapidly raise the danger.

Confidence

Moderate

Avalanche Summary

No new avalanches were reported by 4:30 pm on Saturday.

A few small (size 1) storm slab avalanches were triggered on Friday by riders and with explosives.

On Thursday there were a few small (size 1-1.5) storm slab avalanches west of Winlaw. North aspect, treeline, 35 cm deep.

Numerous natural and human-triggered large (size 2) avalanches were reported on Tuesday and Wednesday. Some were remotely triggered from far away..

Snowpack Summary

The snowpack has two buried weak layers of concern:

A layer of facets and surface hoar buried 30 to 60 cm deep, covered by a thin crust at lower elevations but remaining active higher up.
A crust and facet combo from the new year down 80 to 100 cm. This layer seems to be becoming active now that it has a significant load over it from the continued trickle of snow.

Currently, the mid and lower snowpack is generally well-bonded, featuring a thick crust near its base.

Weather Summary

Saturday Night

Cloudy with 5 to 10 cm of snow, south alpine wind 10 to 30 km/h, treeline temperature 0 °C, freezing level 2500 m.

Sunday

Cloudy with 5 to 10 cm of snow or rain, southwest alpine wind 30 km/h, treeline temperature 2 °C, freezing level 2500 m.

Monday

Mostly cloudy with a trace of snow or rain, south alpine wind 25 to 35 km/h, treeline temperature 5 °C, freezing level 3000 m.

Tuesday

Mostly cloudy with 5 cm of snow, south alpine wind 35 to 45 km/h, treeline temperature 3 °C, freezing level 2000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

The first few hours of rain will likely be the most dangerous period.
Make conservative terrain choices and avoid overhead hazard.
Avoid steep convex slopes.

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.