Avalanche Forecast

Archived

Apr 6th, 2023–Apr 7th, 2023

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Purcells, Dogtooth, East Purcell, West Purcell.

Continue to use good travel habits, and use extra caution in thin, rocky start zones.

Carefully choose the terrain you play in. A weak, unpredictable layer continues to lurk near the bottom of the snowpack.

Confidence

Moderate

Avalanche Summary

On Wednesday, west of Panorama, a large (size 2.5), naturally triggered wind slab avalanche was reported. It occurred on a Northeast aspect in the alpine during a stormy period.

A few skier-triggered storm or wind slab avalanches were triggered on Tuesday. All were relatively thin (10 -20 cm), occurring along exposed ridge features in the western Purcells.

On Sunday a size 3 naturally triggered, deep persistent slab avalanche was reported in the western Purcells (southwest of Panorama). It occurred in large alpine terrain, west facing at 2800 m.

Snowpack Summary

Dry, powder snow remains on shaded (northerly) slopes. Moist snow or thin crusts exist on solar aspects at all elevations.

The mid-snowpack may still contain a number of weak layers, primarily in sheltered treeline terrain. However, no recent avalanche activity has occurred on these layers suggesting they are likely no longer a primary concern.

The lower snowpack includes a widespread layer of large, weak facets and/or depth hoar crystals. This weak layer has been responsible for several very large and destructive avalanches throughout the season, including one in the last week.

Weather Summary

Thursday Night

Mostly clear, cloudy on the west side of the Purcells. No new snow expected. Light southwest ridgetop wind, trending to moderate at higher elevations. Freezing level 1800-2000 m. Treeline temperature around -2°C.

Friday

Partly cloudy, fully cloudy on the west side of the Purcells. No new snow expected. Light southwest ridgetop wind, trending to moderate at higher elevations. Freezing level 2000-2200 m. Treeline temperature around -2°C.

Saturday

Mostly cloudy, with scattered flurries and trace accumulation. 5-15 cm possible on the west side of the Purcells. Light southwest ridgetop wind, trending to moderate at higher elevations. Freezing level around 2000 m.

Sunday

Mostly cloudy. 0-5 cm of snow expected. Light southwest ridgetop wind, trending to moderate at higher elevations. Freezing level around 2400 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.
Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Carefully evaluate bigger terrain features on an individual basis before committing to them.

Problems

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.