Avalanche Forecast

Archived

Mar 4th, 2022–Mar 5th, 2022

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

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, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Lizard-Flathead.

Start on simple terrain, and avoid exposure to terrain traps. Storm slabs and loose snow have been avalanching under the weight of a rider, and the snowpack needs more time to adjust to the new load. Avalanche danger may be higher on sunny slopes.

Confidence

Moderate - The snowpack structure is generally well understood. Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

General cooling and clearing trend with cold northern air providing good refreezes overnight, but upslope flow will continue to bring spotty cloud cover and bits of snowfall through the forecast period.

Friday Night: Decreasing cloud through the night. Possible trace of snow expected, but unstable air could lead to localized heavier snowfall. Light variable wind. Freezing levels at valley bottom. Treeline low around -10 °C.

Saturday: Mostly sunny. No new snow expected. Light northeast ridgetop wind, trending to moderate at higher elevations. Freezing level rising to 1500 m through the day. Treeline high around -4 °C

Sunday: Partly cloudy. 0-5 cm of snow expected overnight, and a possible trace through the day. Light northeast ridgetop wind, trending to moderate at higher elevations. Freezing level at valley bottom overnight, rising to 1250 m through the day.

Monday: Partly cloudy. 0-2 cm of snow expected. Light west ridgetop wind, trending to strong northwest at higher elevations. Freezing level at valley bottom overnight, rising to 1500 m through the day.

Avalanche Summary

On Friday, near Fernie, numerous natural, rider, and explosive triggered storm slab avalanches up to size 2.5 were reported. Also, Numerous loose wet avalanches up to size 1.5 were reported in steep terrain on all aspects below tree line.

On Thursday, there were reports of many small Loose Wet avalanches in steep terrain below tree line across the region.

Multiple professional operations have reported that visibility of alpine start zones has been poor, we expect that we will see more evidence of natural avalanches from this storm as the weather clears over the weekend.

Snowpack Summary

20-35 cm of new snow fell with light winds overnight on Thursday and into Friday morning. A melt freeze crust may be present underneath this new snow, on all aspects, and reported as high as 2100 m.

The Lizard Range has received over 120 mm of water from this system which has translated to about 50-70 cm of heavy, upside down type snow at treeline elevation. Snow has generally been rain-soaked below 1600 m. Expect to find moist snow underneath the melt-freeze crust, especially at lower elevations.

The recent storm snow sits on a variety of old surfaces buried in late February: sun crusts, freezing rain crusts, old wind-pressed snow or cold, weak snow crystals on shaded aspects.

Storm snow avalanches may step down to old persistent layers such as the surface hoar layer buried at the end of January. The distribution of this layer is spotty in nature but has produced avalanches and concerning snowpack test results in the past week, mostly in the Flathead. While it does not appear to be as widespread or reactive in the Lizard Range, it has been found in some locations.

The lower snowpack is generally well consolidated, with a crust/facet layer from early December found near the ground. It is currently considered dormant but could become active later this season.

Terrain and Travel

If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
Use small low consequence slopes to test the bond of the new snow.
Minimize exposure to sun-exposed slopes when the solar radiation is strong.
Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
Avoid rock outcroppings, convexities, and anywhere the snowpack is thin and/or variable.

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.

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.