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

Feb 3rd, 2021–Feb 4th, 2021

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Sea To Sky.

Wind loading is expected on southerly slopes with a forecast change in wind direction, which is not the typical pattern for the region.

A persistent weak layer is now buried up to 100 cm. Avalanches on this layer will become harder to predict, so a conservative approach is key.

Confidence

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

WEDNESDAY NIGHT - Mainly cloudy with a few flurries / moderate to strong northwest wind / alpine low temperature near -10 

THURSDAY - Mainly cloudy with a few flurries / moderate to strong northwest wind / alpine high temperature near -7

FRIDAY - Mainly cloudy / strong northwest wind, easing to moderate west wind / alpine high temperature near -5 / freezing level 1400 m 

SATURDAY - Mainly cloudy with scattered flurries / moderate to strong west wind / alpine high temperature near -7

Avalanche Summary

Human triggered avalanches are still expected to be easy to trigger in many areas.

There have been reports of numerous size 1-2 natural, human and explosives triggered avalanches every day since Saturday. Many of these avalanches have failed on the recently buried persistent weak layer.

Snowpack Summary

50-100 cm of recent fresh snow sits on a persistent weak layer that consists of facets at upper elevations, surface hoar in sheltered areas, a melt-freeze crust below 1900 m, and a sun crust on south-facing slopes. There could be more than 100 cm on this layer in wind loaded areas.

A crust from early December may be found around 200+ cm deep in the snowpack. In shallow rocky areas, it may still be possible to trigger this layer. In deeper snowpack areas, it appears to be unreactive.

Terrain and Travel

  • Keep in mind that human triggering potential persists as natural avalanching tapers off.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • Be aware of highly variable recent wind loading patterns.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.