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Avalanche Forecast

Archived

Apr 1st, 2021–Apr 2nd, 2021

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

Purcells.

High elevation north aspects are still offering good skiing and riding conditions, but this is likely where you'll find some overlap with wind slab distribution. Analyze slopes for wind loading patterns and seek out more sheltered, low density snow.

Confidence

Moderate -

Weather Forecast

Thursday night: Increased cloud with possible isolated flurries. Light to moderate southwest winds.

Friday: A mix of sun and cloud. Light southwest winds. Alpine high temperatures around 0 with freezing levels to 2000 metres.

Saturday: A mix of sun and cloud with cloud increasing. Light southwest winds. Alpine high temperatures around +1 with freezing levels to 2200 metres.

Sunday: Cloudy with continuing flurries from the overnight period and 5-15 cm of new snow above about 1700 metres. Light west winds. Alpine high temperature around -3 with freezing levels to 1700 metres.

Avalanche Summary

Reports from Wednesday showed a trend toward observations of small (size 1) wet loose point releases from steep solar aspects. Explosives control in the Golden area produced several small (size 1) wind slab releases from north through east facing ridgetop features. Minimal propagation was noted in these results.

On Monday, numerous skier and explosive triggered storm slab avalanches were reported size 1-1.5, largely on NW aspects. By Tuesday, storm slabs became more stubborn to explosives and results were limited. Observations in the Hellroaring area, which received less snow, include a few size 1 wind slabs and a cornice-triggered size 1.5.

Reports during the storm on Sunday included several natural storm slabs size 1-2 and a natural size 2 loose wet avalanche on a northeast aspect around 1700 m. It is suspected to have scrubbed down to a crust near the ground, as rain and warm temperatures destabilized the full depth of the snowpack. Larger wet loose (to size 3.5) and wind slab avalanches (to size 3) from this cycle have been observed more recently.

Snowpack Summary

Surface melt-freeze crusts exist on solar aspects and below about 2000 metres. Above this elevation, 15-40 cm of recent snow has otherwise seen some redistribution by southwest to northwest wind, and seems to be bonding well with underlying surfaces.

A widespread crust layer from the mid-March warm spell can be found 30-60 cm deep, and small surface hoar has been observed at this depth on some isolated north-facing slopes. Reports suggest the snow is generally well bonded to these layers. Deeper layers are strong and have been unreactive over the past few weeks. 

Terrain and Travel

  • Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.
  • Extra caution is needed around cornices under the current conditions.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.

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.