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 10th, 2019–Dec 11th, 2019

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

Regions

South Columbia.

Don't underestimate the potential for human triggered avalanches. Keep your guard up especially as you transition into wind exposed terrain, and evaluate conditions before committing to larger features.

Confidence

Moderate - Uncertainty is due to the complexity of the snowpack’s structure. Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

Tuesday Night: Cloudy with scattered flurries, alpine low -9, moderate southwest wind.

Wednesday: Mainly cloudy with isolated flurries, alpine high -4, moderate southwest wind increasing to strong overnight.

Thursday: Flurries accumulating 5-10 cm, alpine high -4, southwest wind gusting to strong.

Friday: Cloudy with scattered flurries accumulating to 5 cm, alpine high -3, light northwest wind.

Avalanche Summary

Although natural avalanche activity has largely subsided, a few natural persistent slabs are still being reported. Monday in the south of the region, a size 2.5 persistent slab avalanche was observed, suspected to have been triggered by wind loading. On Monday, skier triggered avalanches up to size 2 were reported on south aspects. Results from explosive control work have been hit or miss, occasionally producing avalanches up to size 3. 

Snowpack Summary

Last week's storm snow has seen some redistribution by the wind. Isolated soft wind slabs can be found in the lee of features such as ridge tops. Below the 40-80 cm of snow from last week, lies a thick layer of faceted crystals, previously wind-affected surfaces, and/or surface hoar in sheltered areas (around treeline and below). The surface hoar layer within the storm snow can still be found in some locations but has not shown recent reactivity.

A weak layer formed in late November is now buried 60-100 cm below the surface. This is the layer of concern relating to the persistent slab avalanche problem. The weak layer may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect. It can most likely be found in areas sheltered from the wind, but open to a view of the sky, such as near treeline. Below this, variety of crusts from late October are buried deeper in the snowpack.

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.