Avalanche Forecast

Issued: Mar 5th, 2019 4:48PM

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.

kdevine, Avalanche Canada

North Columbia.

Wind slabs continue to be reactive at upper 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 -12WEDNESDAY - Cloudy with sunny periods / southeast winds 10-25 km/h / alpine high temperature near -6THURSDAY - Flurries, 5 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 -10

Avalanche Summary

Reports from the past couple of days show a continuation of wind slabs reacting to ski cuts, with a trend toward smaller (size 1) releases. Small (size 1-1.5) loose dry avalanches have also been observed releasing naturally from steeper, sun exposed slopes in recent days.Reports of human triggered persistent slab avalanches on the January weak layers have been on the decline, suggesting these layers have evolved into a lower likelihood avalanche problem, but one that still requires a measure of discipline to manage effectively.

Snowpack Summary

Weeks of mainly dry, windy, and cold weather have transformed the snowpack at upper elevations into a mix of wind-affected surfaces and wind slabs on all aspects. These wind slabs have shown prolonged reactivity because they are sitting on facets (sugary snow).There are a couple of prominent weak layers in the upper snowpack that were buried in mid and late January. These can be found approximately 40-80 cm deep. Both layers consist of surface hoar (feathery crystals) and may be associated with a crust on steep, south facing slopes. These weak layers have been most reactive at lower elevations, and 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

Wind slabs can be found on all aspects, and have recently shown prolonged reactivity due to the weak, faceted snow they sit above.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Steep and rocky terrain are likely places to trigger buried wind slabs.Exercise increased caution around wind loaded pockets near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Persistent Slabs

Two persistent weak layers are buried approximately 40 cm and 75 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.

Maintain diligent group management around open and/or sparsely treed slopes at treeline and below.Exercise increased caution around low elevation cut-blocks where this layer has been well preserved.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Unlikely

Expected Size

1 - 2

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