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 23rd, 2012–Feb 24th, 2012

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

South Columbia.

A Special Public Avalanche Warning has been issued for this region for February 24-27. Current conditions are very touchy and require extremely conservative decision making.

Confidence

Good

Weather Forecast

Friday: Moderate snow beginning in the morning - 5-15cm. The freezing level (FL) is around 500-800m. Ridge top winds should be moderate from the SW. Saturday: Continued moderate snowfall - an additional 10-20cm overnight and through the day. FL 800-1000m. Winds should ease to light from the west. Sunday: Unsettled conditions with convective flurries likely. FL drops to valley bottom. Winds are light and variable.

Avalanche Summary

A large natural avalanche cycle occurred on Wednesday. Slab avalanches were reported up to Size 3.5 on all aspects and at all elevations. There were also numerous reports of skier triggered and remotely triggered avalanches on a variety aspects. The potential for human triggered avalanches remains high in all terrain over 30 degrees.

Snowpack Summary

Moderate west-northwest winds have created weak wind slabs in exposed alpine and treeline terrain. Up to 70cm of new snow now sits on the February 16th Surface Hoar layer and is slowly settling into a cohesive slab. The February 8th weakness is now down 80-100cm. This layer is a combination of weak layers: In most locations it marks a widespread surface hoar layer. On steep south & west facing aspects a sun crust that formed during the drought was also buried on Feb. 8th. This crust likely has a bit of faceting below it too, meaning that most terrain in the region has a weak layer 40-60cm under the snow surface. These buried weaknesses have made conditions very tricky with the potential for triggering in lower angle terrain and from a distance. It is should be noted that large cornices remain widespread throughout the region and may fail as temperatures fluctuate over the next few days.

Problems

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.

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.