Avalanche Forecast

Archived

Feb 12th, 2023–Feb 13th, 2023

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Lizard-Flathead, South Rockies, Flathead, Lizard, Bull, Elkford East, Elkford West.

Use caution in wind-affected areas on Monday as new snow and wind will form fresh wind slabs.

Confidence

Moderate

Avalanche Summary

No new avalanches were reported on Saturday. On Friday, several skier-triggered wind slab avalanches were reported in the Fernie area. They were size 1 to 2, occurring in both alpine and open forested terrain, as illustrated in MIN reports here, here, and here.

Wind slab avalanches will continue to be a problem on Monday with more snow and wind expected. Deep persistent slab avalanches should also be on your radar in the Elkford and Flathead areas.

Snowpack Summary

Up to 15 cm of new snow is possible on Monday, which will fall above various layers, including sun crusts and hard wind-affected snow. Sheltered, shaded areas will likely have deeper soft snow from last week.

In the Lizard range specifically, the mid-pack is consolidated with a supportive 10 to 20 cm thick frozen crust buried 80 to 100 cm.

In the Elkford and Flathead areas, deeply buried weak layers are slowly gaining strength but are still a concern, especially in steep rocky terrain features where the snowpack is thin.

Weather Summary

Sunday night

Cloudy, flurries start in the early morning with trace accumulations of snow, 50 to 70 km/h southwest wind, treeline temperatures around -4 ºC.

Monday

Cloudy with scattered flurries bringing 5 to 15 cm of snow, 40 to 60 km/h southwest wind, treeline temperatures around -4 °C with freezing level around 1300 m.

Tuesday

Mix of sun and cloud, isolated flurries with trace amounts of snow, 20 km/h northeast wind, treeline temperatures drop to -8 °C.

Wednesday

Mix of sun and cloud, no significant precipitation, 30 km/h west wind, treeline temperatures around -6 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.