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 19th, 2019–Dec 20th, 2019

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

Regions

South Columbia.

An intense winter storm is delivering heavy snowfall and strong winds. Widespread avalanche activity is expected. Avoid avalanche terrain.

Confidence

High - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.

Weather Forecast

THURSDAY NIGHT - Periods of snow, 15-25 cm / southwest wind, 30-60 km/h / alpine low temperature near -9

FRIDAY - Snow, heavy at times, 20-40 cm / southwest wind, 40-80 km/h / alpine high temperature near -4 / freezing level 1500 m

SATURDAY - Snow, heavy at times, 15-25 cm / southwest wind, 40-80 km/h / alpine high temperature near -4 / freezing level 1500 m

SUNDAY - Cloudy with sunny periods and isolated flurries / southeast wind, 10-20km/h / alpine high temperature near -8

Avalanche Summary

A widespread natural avalanche cycle is expected on Friday due to heavy snowfall, warm temperatures and strong to extreme winds.

Preliminary reports from Thursday suggest that an avalanche cycle was ongoing with reports of natural, explosives and human triggered avalanches up to size 2.5.

Previous heavy snowfall resulted in an avalanche cycle on Tuesday and Wednesday. Numerous natural and human triggered avalanches up to size 2.5 were reported.

Snowpack Summary

An intense winter storm is underway in the South Columbia's with up to 25 cm on Thursday night, and another 20-40 cm expected throughout the day on Friday. This will bring total recent snow amounts to 50-90 cm.

60-120 cm of snow now sits above a widespread layer of large, feathery surface hoar crystals. With more snow continuing to accumulate above this layer over the next few days, it will likely remain very sensitive to human-triggering.

A weak layer formed in late November is now buried around 1 m below the surface. This is the layer of concern relating to the listed persistent slab avalanche problem. The weak layer may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect. Below this, a variety of crusts from late October are buried deeper in the snowpack.

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.