Avalanche Forecast

Archived

Mar 27th, 2023–Mar 28th, 2023

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.

Alpine

Natural avalanches unlikely, human triggered possible.

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.

Large triggers such as cornice falls continue to trigger persistent slabs. Human triggering of the persistent and deep persistent slab remains possible especially in terrain with thin to thick snowpack depths.

Solar warming should once again factor into your trip planning - avoid exposure to southerly slopes and exposure to cornices during peak warming.

Elevated hazard rating below tree line reflects increasing freezing level and solar warming - take advantage of good overnight freezing by starting and finishing early.

Confidence

Moderate

Avalanche Summary

Limited new activity noted on the Icefields Parkway on Sunday - a couple of dry loose size 1.5 in the alpine Mount Cirus; serac activity estimated size 2 off of Stutfield.

Maligne patrol noted a cornice triggered persistent slab size 2.5 east aspect and a size 2 persistent slab west aspect both visible just south of Medicine lake.

Cornice failures and loose wet avalanches may increase late afternoons with forecasted clear skies and rising daytime freezing level.

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

Snowpack Summary

2-10cm of new snow from early Sunday sits over a breakable sun crust at all elevations on solar aspects. Approximately 20-50cm down is a persistent slab sitting over a facet layer in sheltered terrain or a weak crust at low elevations / southerly slopes. The lower snowpack is generally weak with large facets and depth hoar at the base.Snow depth varies from 60-170cm.

Weather Summary

Surface ridge of high pressure will provide for clear skies on Tuesday. Freezing level will rise to 1600m with light northerly winds. Mostly clear conditions will continue on Wednesday. An approaching low from the north will bring increasing cloud late Wednesday with the potential for isolated flurries. Freezing level will reach 2100m. Mix of sun and cloud on Thursday with continued diurnal temperature pattern.

Terrain and Travel Advice

Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Cornices become weak with daytime heating or solar exposure.

Problems

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.

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.