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

Dec 30th, 2020–Dec 31st, 2020

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 Rockies.

Wind slabs may linger up high and it is still possible to trigger large avalanches on buried weak layers.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

WEDNESDAY NIGHT: Cloudy with light snowfall, accumulation 1 to 3 cm, 30 to 50 km/h west wind, alpine temperature -9 C.

THURSDAY: Partly cloudy, 20 to 30 km/h northwest wind, alpine temperature -8 C.

FRIDAY: Cloudy with snowfall, accumulation 5 cm, 20 to 50 km/h southwest wind, alpine temperature -5 C.

SATURDAY: Cloudy with snowfall, accumulation 10 to 15 cm, 40 km/h southwest wind, alpine temperature -5 C.

Avalanche Summary

No recent avalanches have been reported in the region.

Snowpack Summary

Wind from predominantly the southwest has redistributed last week's snow, resulting in wind slabs in exposed terrain features at and above treeline elevations. Wind-affected snow in exposed terrain and soft snow in sheltered terrain overly a hard melt-freeze crust below 1900 m.

Weak layers of feather surface hoar and/or sugary faceted grains may be found above a hard melt-freeze crust around 40 to 90 cm deep. Avalanches were reported on these layers on December 23 and 25.

The base of the snowpack consists of faceted grains and a hard melt-freeze crust from early-November. The most recent activity on this layer was on December 23.

Terrain and Travel

  • Watch for areas of hard wind slab on alpine features.
  • Avoid slopes that sound hollow or drum-like.
  • Be aware of the potential for large avalanches due to the presence of buried weak layers.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.