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 17th, 2020–Dec 18th, 2020

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

Regions

Cariboos.

Recent snow is gaining cohesion and slab properties over a weak layer of surface hoar. Scattered reports document increasing reactivity, expect to find an increasingly touchy slab more snow and wind on the way.

Confidence

Low - Uncertainty is due to the limited number of field observations. Recent weather patterns have resulted in a high degree of snowpack variability within the region.

Weather Forecast

THURSDAY NIGHT - Mainly cloudy with flurries, 5 cm / southwest wind, 25-45 km/h / alpine high temperature near -8 

FRIDAY - Cloudy with flurries, 5-15 cm / southwest wind, 45-70 km/h / alpine high temperature near -5

SATURDAY - Snow, 5-15 cm / southwest wind, 45-70 km/h / alpine high temperature near 0 / Freezing level rising to 1500 m

SUNDAY - Flurries, 5-15 cm / southwest wind, 20-40 km/h / alpine high temperature near -5

Avalanche Summary

Snowmobilers remotely triggered a storm slab over surface hoar Wednesday near Allen Creek (MIN report). Keep this in mind as I expect slabs to become increasingly reactive as fresh snow gains cohesion and bonds over a weak and touchy surface hoar layer.

Several large natural avalanches were reported last Friday at Chappel Creek (see this MIN report). These avalanches occurred on south aspects at treeline elevations. Based on the depth of these avalanches, they likely failed on recently buried surface hoar and/or sun crust layers. 

Snowpack Summary

About 20-40 cm (with the higher numbers surrounding Blue River) low density snow has buried a layer of surface hoar in many areas. Slabs are becomingly increasingly reactive as fresh snow bonds and gains cohesion where it overlies touchy surface hoar.

A weak layer of surface hoar that was buried about a week ago is now down 30-60 cm. In many areas the weak layer exists as a crust, and in some areas, it has been found as surface hoar. 

Near the base of the snowpack is a crust that was buried in early November. This crust likely has weak facets associated with it. There have been no recent avalanches reported on this layer, though it may be possible to trigger from shallow, rocky terrain.

Terrain and Travel

  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Avoid freshly wind loaded terrain features.
  • As the storm slab problem gets trickier, the easy solution is to choose more conservative terrain.

Problems

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.