Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Mar 20th, 2021–Mar 21st, 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, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Purcells.

Expect southwesterly winds and flurries to form fresh slabs around ridges and lee features. Be mindful that best riding conditions may overlap with the deepest deposits and touchiest slabs.

Confidence

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Weather Forecast

SATURDAY NIGHT: Isolated flurries, up to 5 cm. Light to moderate southwest wind, alpine temperature low -11C, and freezing level dropping to valley bottom.

Weather models are showing a band of moisture moving from the Shuswap to the Purcells through the Nakusp area late Saturday evening and overnight, and may produce enhanced precipitation in localized areas near the South Columbia and Rogers Pass Forecast Regions of up to 15cm. 

SUNDAY: Cloudy with flurries, up to 10 cm of snow during the day and into Sunday night. Light to moderate southwest wind, alpine high -5C, and freezing level beginning near valley bottom rising to about 1400 m.

MONDAY: Cloudy and lingering flurries, 5 cm. Light northwest wind, alpine high -5C, and freezing level beginning near valley bottom rising to about 1500 m.

TUESDAY: Mostly sunny with patchy clouds. Moderate southwest wind, alpine high 0C, and freezing level beginning near valley bottom rising above 1500 m.

Avalanche Summary

A few small loose wet avalanches were reported on Wednesday and Thursday on solar aspects. A small wind slab was also reported from a high elevation east facing aspect Thursday.

On Tuesday, natural cornice falls were observed. Reports indicated that they did not pull a slab on the slope below. Sunshine may initiate loose wet avalanches on steep solar slopes and continue to weaken cornices.

Snowpack Summary

5-15 cm fresh snow accumulated around the region Saturday and covers dry snow and surface hoar (up to 15 mm) on northerly aspects above 1800m, and crusts on solar aspects and lower elevations. Flurries and wind have formed fresh slabs in immediate lees. Large cornices may still pose a hazard close to alpine ridgelines, especially when it's warm and sunny.

A persistent weak layer of facets 40-60 cm deep that was buried in mid-February was reactive in the north of the region earlier this month but since the first week of March, only a couple of avalanches have been reported on this layer resulting from large triggers such as cornice fall. There are several other weak layers deeper in the snowpack composed of old surface hoar, facets and/or crusts, all of which have been recently unreactive.

Terrain and Travel

  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Wind slabs are most reactive during their formation.
  • Avoid exposure to slopes that have cornices overhead.
  • A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.

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.