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

Jan 3rd, 2012–Jan 4th, 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 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.

Regions

Cariboos.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

A warm front passes over this region late today (Tuesday) bringing light or locally moderate precipitation--say 10 to 15 cm between Tuesday evening and midday on Wednesday. Freezing levels will rise to approximately 1800 m during this time and strong southwesterly winds are expected. On Wednesday evening, a cold front will pass, bringing another similar pulse of snow (10-15 cm between Wednesday evening and Thursday morning) and freezing levels down to surface levels. Late Thursday and into Friday a ridge of high pressure develops, keeping things cold and mostly dry. Winds should ease to light by Friday afternoon.

Avalanche Summary

A size 2 human-triggered avalanche occurred on Monday on a northwest aspect at 1700 m. The avalanche was triggered in wind slab; the fracture line was 30 cm deep. Several large cornice-triggered avalanches also occurred on Sunday and Monday. One stepped down into lower facet layers producing a crown up to 2 m deep.

Snowpack Summary

Total snowpack depths are approximately 250 cm at treeline. Recent daily new snow amounts have not been particularly high in the last few days, giving the storm snow a chance to settle and gain a little strength. Strong winds have redistributed some of this snow into the classic lee areas in exposed terrain-behind ridgelines, summits and exposed rolls and features. A surface hoar/facet/crust interface from mid-December is well preserved and acting as a persistent weak layer. This is buried 100 to 150 cm deep and has been reactive to natural and human triggers. The increased depth is beginning to make triggering more difficult but bear in mind it also increases the size of anything that does go on this layer, which in turn increases the consequences.

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.