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 24th, 2012–Feb 25th, 2012

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

Regions

South Rockies.

Confidence

Fair - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

Moderate to heavy snowfall on Friday is expected to continue overnight into Saturday morning. Expect 10-15 cm in the West of the region and about 5-10 cm in the East by Saturday noon. The freezing level should remain at about 800 metres during the storm and then drop down to valley bottoms by Saturday evening. Winds are forecast to be moderate to strong from the South until about midnight and then ease a bit and clock to the west for the morning hours of Saturday. Expect to see some convective flurries on Sunday as a ridge of high pressure slides in behind the storm bringing light northerly winds by late in the day. There may be some sunny breaks on Sunday, and mostly clear skies and cooler temperatures for Monday.

Avalanche Summary

Natural avalanches have become less frequent, but human triggered avalanches continue to release from light additional loads. Skier controlled avalanches up to size 2.0 were reported today to be easy to initiate in some areas and a bit more stubborn in others. The forecast new snow and wind may cause new windslabs that may overload the PWL in some areas.

Snowpack Summary

Gusty wind has transported snow into windslabs at all elevations. In southern and western parts of the region, 40-50 cm of recent snow sits of a highly reactive weak layer of crusts, surface hoar and facets. At 1950 metres elevation we have some snow pack test results that show that the 40 cm slab of snow above the February 8th weak layer is sliding with easy to moderate forces applied and it is propagating widely with either sudden planar or sudden collapse characteristics. The slab is reported to be less consolidated on northerly aspects than it is on southerly aspects. In areas further north, less snow has fallen on this interface--in the northern Elk Valley for instance, only around 15-20 cm lies above this interface. In lower snow areas, avalanche activity will likely lag behind higher snow areas, except for areas which have seen significant wind transport. In general, the mid-pack is quite strong in most locations. However, lingering concern remains for basal facets, particularly in shallower snowpack areas with steep, rocky start zones.

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.