Avalanche Forecast

Issued: Mar 5th, 2019 4:49PM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Wind Slabs and Persistent Slabs.

Avalanche Canada kdevine, Avalanche Canada

Wind slabs continue to be reactive at higher elevations. A persistent slab problem still exists at lower elevations and has been responsible for occasional human-triggered avalanches.

Summary

Confidence

Moderate -

Weather Forecast

TUESDAY NIGHT - Clear periods / southeast winds 20-35 km/h / alpine low temperature near -9WEDNESDAY - Cloudy with sunny periods and isolated flurries / southeast winds 10-25 km/h / alpine high temperature near -6THURSDAY - Flurries, 5-10 cm / southwest winds 10-25 km/h / alpine high temperature near -7FRIDAY - Cloudy with scattered flurries / west winds, 15-25 km/h / alpine high temperature near -11

Avalanche Summary

Observations from the past few days have shown size 1-2 wind slabs releasing with skier traffic on a range of aspects in the alpine and at treeline. A few storm slabs were reported in the south of the region where up to 30 cm of snow fell at the end of the week. Small (size 1-1.5) loose dry avalanches have also been observed releasing naturally from steeper, sun exposed slopes. Persistent slab avalanche activity on the mid-January weak layer has slowed down, but not stopped. This layer has evolved a lower likelihood avalanche problem focused at treeline and below. Check out the great photos from a MIN dated from February 23 for a higher consequence example of this layer's potential. Take note of the low angle terrain, treeline elevation, and the light load of a single ski track that triggered this avalanche.

Snowpack Summary

Up to 20 cm of recent snow exists in a few areas in the south of the region from some light snowfall at the end of last week. This snow likely sits on a sun crust on sun-exposed aspects. Below any new snow, strong ridge-top winds (most recently from the northeast) have created wind slabs on all aspects at upper elevations. These wind slabs have shown prolonged reactivity because they are sitting on facets (sugary snow).There are two prominent weak layers in the upper snowpack that were buried in mid and late January. They can be found between 40-90 cm below the surface. These layers consist of surface hoar (feathery crystals) and may be associated with crusts on steeper, south facing slopes. These weak layers have been most prominent and most reactive at lower elevations - especially below treeline.The lower snowpack is generally considered to be strong, except for shallow, rocky areas where the cold temperatures continue to facet (weaken) the snowpack.

Problems

Wind Slabs

An icon showing Wind Slabs
Wind slabs can be found on all aspects and continue to be reactive due to the weak, faceted snow they sit on.
Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Avoid wind loaded pockets near ridge crests and back off from slopes that feel hollow or drum-like.Steep and rocky terrain are likely places to trigger buried wind slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Persistent Slabs

An icon showing Persistent Slabs
A pair of persistent weak layers are buried approximately 40 cm and 80 cm below the surface. These layers have evolved into a lower likelihood avalanche problem that still demands slope assessment and diligent group management at lower elevations.
Exercise increased caution around low elevation cut-blocks where this layer has been well preserved.Maintain diligent group management around open and/or sparsely treed slopes at treeline and below.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Unlikely

Expected Size

1 - 2

Valid until: Mar 6th, 2019 2:00PM