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

Mar 5th, 2012–Mar 6th, 2012

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

Regions

South Coast.

Confidence

Good

Weather Forecast

Flurries are expected to end today and skies should clear by dinner time causing overnight temperatures to drop below freezing in the valley bottoms. Tuesday is forecast to be sunny with light northwest winds at ridgetops. Alpine temperatures should stay close to -10.0 in the afternoon. Steep solar aspects may see some moist snow at treeline. High pressure is expected to continue to dominate the area on Wednesday causing continued clear skies and light northerly winds. Clear skies are forecast to continue on Thursday morning. The wind is expected to veer to the southwest by the afternoon, and the freezing level may rise up to about 2200 metres in advance of the next system moving in from the Pacific.

Avalanche Summary

A couple of small size 1.0-1.5 thin slab avalanches were reported from Sunday. Some of the large rock slab features along the Coquihalla highway corridor were starting to slide; these are not in terrain suitable for recreation. I suspect that there will be reports of more activity as the storm clears and operators can see some alpine terrain.

Snowpack Summary

There has been about 50 cm in the past 24 hours in the Coquihalla area, and about 35cm in the Duffey Lake area. Moderate to strong southerly winds created windslabs in the alpine and at treeline. The freezing level went up to about 1600 metres on Sunday causing moist snow up to about 1800 metres. A trailing cold front brought the temperatures down at the same time as the most intense snowfall. A weak layer of buried stellar crystals and/or decomposed and fragmented crystals is now buried by about 70-90 cm of storm snow. The new windslabs may take a couple of days to settle and bond.

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.

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.