Avalanche Forecast

Archived

Mar 22nd, 2023–Mar 23rd, 2023

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.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Jasper, Brazeau, Churchill, Cirrus-Wilson, Fryatt, Icefields, Maligne, Marmot, Miette Lake, Pyramid.

Spring like conditions persist into Thursday afternoon, start early and finish early as solar warming is having the strongest effect typically by mid-afternoon.

The sun is heating up cornices, cliffs and steep rocky features triggering wet loose avalanches and deeper slab instabilities.

Ice climbers, be cautious of narrow gullies that act as terrain traps, as even small slides can have significant consequences.

Confidence

Moderate

Avalanche Summary

Several wet loose avalanches observed in the last week occurring mid to late afternoon at all elevations southerly aspects with many stepping down to the basal weakness or triggering persistent and deep persistent slab avalanches. Large to very large deep persistent slabs have been observed throughout the region, generally triggered by a small loose wet slide, or a cornice fall.

Don't forget to post avalanche observations to the MIN.

Snowpack Summary

Sun crust on solar aspects at all elevations breaking down by early to mid afternoon. Approximately 20-30cm down is a buried sun crust at low elevations on steep southerly slopes and a surface facet layer in sheltered terrain. The mid-pack is 40 to 80cm of supportive facetted snow. Near the ground it is generally weak with large facets and depth hoar.

Weather Summary

On Thursday, expect sun with cloudy periods and freezing levels at 1600 m with light southwest winds. Late Thursday, the ridge of high pressure will give way to a more active pattern bringing 7 cm of snow, light southwesterly winds and freezing levels to 1500 m by the end of Friday.Saturday, expect scattered flurries with up to 5 cm accumulation and winds switching to northwesterly, freezing levels at 1500 m.

Detailed weather forecasts from Avalanche Canada: https://avalanche.ca/weather/forecast

Terrain and Travel Advice

Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Be alert to conditions that change with elevation and sun exposure.
Avoid exposure to steep sun exposed slopes.

Problems

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.

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.