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

Jan 17th, 2023–Jan 18th, 2023

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

Regions

South Coast Inland, Birkenhead, Duffey, South Chilcotin, Stein, Taseko.

Avalanche hazard may seem to be improving under foot; however, be mindful that deep instabilities remain. Hurley and Birkenhead are the bulls-eye for a poor snowpack structure. Uncertainty is best managed through conservative terrain choices.

Confidence

Moderate

Avalanche Summary

The snowpack structure, with its mid and basal problems, mean avalanche reports remain relevant, even if several days old.

On Monday cornice chunks released slabby pockets in cliffy terrain below.

On Saturday Hurley was the bulls-eye for avalanche activity on persistent weak layers in the middle and bottom of the snowpack. Surface hoar on the Christmas crust was releasing naturally, intentiionally, remotely, and with direct human triggers on gentle slopes near treeline (1800 to 1900 m) with crowns up to 80 cm thick. Some natural avalanches size 3 to 3.5 and ran full path from the alpine to valley bottom.

Thanks for the observations and please continue to post your reports and photos to the Mountain Information Network. It is really helpful for forecasters!

Snowpack Summary

The region's generally weak snowpack structure remains.

Last week's 20-30 cm of snow and southerly winds means wind slabs may linger. Below 1900 m there was a mix of rain and snow which is freezing into a crust.

Mid-pack: 50 to 70 cm down is a crust formed in late December -- this appears to be the snowpack's primary critical layer. Between 1900 and 1700 m surface hoar can be found above this crust which was reactive last week. This crust varies in thickness with terrain and elevation, in many places it's more of a soft-weak-rotting section of the snowpack.

Lower-pack: There is a widespread weak layer of facets and depth hoar at the bottom of the snowpack. Snowpack depths around treeline are about 150 cm deep.

Weather Summary

Tuesday Night: South wind strengthens to moderate, strong at high elevations. Trace to 5 cm of new snow. Freezing level near 1000 m. Treeline temperatures around -5 C.

Wednesday: Moderate to strong southwest wind at high elevations, lessening to moderate in the afternoon. 5 to 10 cm of new snow. Freezing level 1000 m, briefly rising to near 1300 m late in the day. Overcast. Treeline temperatures around -5 C.

Thursday

Mix sun and cloud. Dry. Cooler with treeline temps around -10 C. Light west wind.

Friday

Mix of sun and cloud. Dry. Treeline temps around -5 C. Light southwest wind.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be mindful that deep instabilities are still present and have produced recent large avalanches.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
  • Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.

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.

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.