Avalanche Forecast

Archived

Apr 28th, 2023–Apr 29th, 2023

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Regions

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

This weekend will be a beautiful time to enjoy recreating in non-avalanche terrain, or in controlled areas like a ski hill.

Confidence

High

Avalanche Summary

Several deep persistent slabs and several loose wet avalanches were observed from the icefields parkway Thursday.No patrol on Friday but widespread natural loose wet avalanche observed from Jasper townsite.

Post avalanche observations to the MIN.

Snowpack Summary

Multiple melt-freeze and sun crusts exist in the upper snowpack on all aspects and elevations except true north facing alpine slopes. As alpine temperatures reach double digits, these crusts are losing cohesion and amalgamating into a moist surface snow. A crust/facet PWL lingers in the mid-pack in many areas at tree line and above. The main concern is the depth hoar and basal facets at the base of the snowpack.

Weather Summary

A dramatic rise in daytime temperatures and strong solar radiation is forecasted for the next several days. There is also forecasted to be warm air trapped at higher elevations overnight, so don't let cool early mornings at valley bottom mislead you into thinking there has been a good overnight freeze.

Terrain and Travel Advice

Only the most simple non-avalanche terrain free of overhead hazard is appropriate at this time.

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.

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.