Avalanche Forecast

Archived

Apr 22nd, 2019–Apr 23rd, 2019

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Sea To Sky.

Wind slabs may react to human triggers around ridges and lee features. Loose wet avalanches remain a concern, best to travel early and avoid moist/wet slopes.

Confidence

Moderate -

Weather Forecast

MONDAY NIGHT: Cloudy with isolated flurries, trace to 5 cm, moderate southwest wind, alpine temperature -2 C, freezing level 1600 m.

TUESDAY: Cloudy with isolated flurries, light to moderate west-southwest wind, alpine temperature -1 C, freezing level 1800 m.

WEDNESDAY: Mix of sun and clouds, light southwest wind, alpine temperature -1 C, freezing level 1800 m.

THURSDAY: Mostly cloudy, light southeast wind, alpine temperature +1 C, freezing level 2200 m.

Avalanche Summary

On Saturday morning around the Whistler Backcountry, a natural wet loose avalanche cycle to size 2 was observed on all aspects from 1900-2200m. Wet slab avalanches to size 3 were observed on loaded northerly features in the alpine. Natural cornices failures to size 2 were also observed and explosives triggered cornices size 2-2.5. Further south in the region, cornices failing naturally triggered large (up to size 3) slab avalanches on the slopes below.

On Friday morning, explosives triggered two wet loose size 2 avalanches and several size 2 cornices, in some cases cornices triggered wet slab avalanches to size 2 on the slopes below. One natural storm slab avalanche was observed on a north aspect, the likely trigger a natural cornice failure on the slope.

On Thursday night and into Friday, a loose wet avalanche and cornice cycle occurred in the region during the storm, producing small to large avalanches (size 1 and 2). Most of the avalanches occurred in the alpine as well as treeline.

Snowpack Summary

Flurries Monday accompanied by south-southwesterly winds accumulated up to 10 cm at upper elevations. In the alpine, cold wind-affected snow is holding onto northerly aspects, and a crust has developed on solar slopes. Warm overnight temperatures are preventing strong crust recovery as you lose elevation, thin crusts will break down quickly during the day increasing the likelihood of loose wet avalanches.

Below treeline the snowpack is saturated and rapidly melting.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

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.