Avalanche Forecast

Archived

Feb 17th, 2023–Feb 18th, 2023

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

Multiple vintages of lingering wind slab mean you can still find trouble if you really go looking for it. If you want to avoid the problem, seek out pockets of sheltered terrain where soft snow still exists.

Confidence

High

Avalanche Summary

This MIN describes a small wind slab avalanche on a northeast facing slope in the upper reaches of the Coal Creek area near Fernie on February 16th.

A wind slab avalanche was reported in this MIN from Fish Bowl near Fernie on February 15th.

Snowpack Summary

For the most part, the upper snowpack has been heavily altered by the wind and, on south aspects, the sun. That being said, opportunities to avoid lingering wind slabs and find softer snow still exist in sheltered, mostly north facing terrain features.

The middle of the snowpack is well consolidated and sits on a thick crust. The bottom of the snowpack still consists of weak, sugary crystals that are slowly gaining strength in areas with a deeper snowpack.

Deep persistent slab avalanches should still be on your radar in areas outside of the Lizard Range such as the Bull River, Elkford, and the Flathead.

Weather Summary

Friday night

Cloudy. Wind from the southwest at 20 km/h. Temperature -6˚C.

Saturday

Cloudy. 2-4 cm of new snow. Wind from the southwest 5 - 10 km/h. Temperature -7˚C in the morning rising to near 0˚C in the afternoon.

Sunday

A short clearing Saturday night into Sunday morning then clouding over again by noon. 5 cm of new snow in the afternoon. Wind from the 10 km/h gusting to 25 km/h. Temperature -7˚C in the morning rising to near 0˚C.

Monday

Cloudy. 5-10 cm of new snow. Wind from the southwest at 10 km/h. Temperature -5˚C in the morning rising to near 0˚C in the afternoon.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Watch for areas of hard wind slab on alpine features.
Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
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.