Avalanche Forecast

Archived

Mar 15th, 2021–Mar 16th, 2021

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 possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

South Coast.

A warming trend will weaken cornices and snow on sun-exposed slopes during the heat of the day. Wind slabs may linger at high elevations.

Confidence

High -

Weather Forecast

MONDAY NIGHT: Partly cloudy, 10 km/h northwest wind, treeline temperature -4 C.

TUESDAY: Mix of sun and cloud, 10 km/h west wind, treeline temperature -2 C, freezing level rising to 1000 m.

WEDNESDAY: Mostly cloudy, 20 to 40 km/h south wind, treeline temperature 0 C, freezing level 1500 m.

THURSDAY: Cloudy with snow or rain, accumulation 10 to 20 cm, 40 to 60 km/h south wind, treeline temperature 0 C, freezing level 1400 m.

Avalanche Summary

We haven't yet received word of avalanche activity from Sunday's storm, but it is likely that storm slabs and wind slabs were triggerable on Sunday and Monday. Looking forward, wind slabs could still be triggered by riders in steep terrain at high elevations. Sun-exposed slopes and cornices will weaken with daytime warming.

Snowpack Summary

Wind slabs may linger in steep, lee terrain features at treeline and alpine elevations from Sunday's 20 cm of snow with strong south to east wind. On sun-exposed slopes above 1200 m, this recent snow will weaken with daytime heating, particularly on sun-exposed slopes. Below 1200 m, a wet snowpack or a hard melt-freeze crust will be found. Along ridgelines, cornices are large and will weaken with daytime heating.

Terrain and Travel

Carefully evaluate steep lines for wind slabs.
Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
Extra caution is needed around cornices under the current conditions.

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.

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.

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.