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 1st, 2021–Feb 2nd, 2021

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

Purcells.

  

New snow and strong southerly winds will form fresh storm slabs reactive to human triggers. Conservative terrain choices will be CRITICAL to playing safe today.

Confidence

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

Weather Forecast

  

MONDAY NIGHT: Snow; 5-15 cm. / Strong, south ridgetop wind / alpine low temperature -5 / Freezing level 1400 m.

TUESDAY: Snow; 5-15 cm. / Moderate, southwest ridgetop wind / alpine high temperature -4 / Freezing level 1500 m.

WEDNESDAY: Mostly cloudy with sunny periods / Light, northwest ridgetop wind / alpine high temperature -7 / Freezing level valley bottom.

THURSDAY: Cloudy / Moderate, northwest ridgetop wind / alpine high temperature -8 / Freezing level valley bottom.

Avalanche Summary

Small but touchy storm slabs propagating across entire features were reported near Golden on Sunday. 

Check out this MIN on the 29th and this MIN on the 28th from near Kicking Horse.

We're continuing to track a layer of surface hoar from early January which was reactive in previous weeks. Refer to: MIN report 1 & MIN report 2 from Hope Creek on the 20th.

Snowpack Summary

25-45 cm of forecast and recent snow will have accumulated by Monday afternoon. This recent snow arrived with light to moderate wind, warm temperatures and will have numerous storm interfaces, including another layer of surface hoar from Saturday that may serve as failure planes. Check out this MIN and this MIN from the south Purcells. All this recent snow sits on top of a known weak layer of widespread surface hoar, facets, sun crust and old wind surfaces from the last drought.   

Buried 50-90 cm is an older surface hoar and / or a thin melt crust from Jan 11th. This layer was more prominent in the north Purcells in sheltered, open slopes at treeline and may become reactive with incoming warm temperatures and snow.

Two deeper layers persist, though they have been recently unreactive. Down 100-150 cm lies the December weak surface hoar / crust / facet layers. Closer to the ground lies the early November crust facet complex. Though unlikely to trigger, caution for these layers remains with large loads in steep, shallow, rocky areas with a thin to thick snowpack or shallow areas below treeline.  

Terrain and Travel

  • Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
  • In times of uncertainty conservative terrain choices are our best defense.
  • Use increased caution at all elevations. Storm snow is forming touchy slabs.
  • Be aware of the potential for large avalanches due to the presence of buried surface hoar.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.