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Avalanche Forecast

Archived

Apr 4th, 2014–Apr 5th, 2014

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

Regions

South Columbia.

Snowfall amounts and solar input are driving the hazard ratings at this time. More snow or more sun than anticipated may push the hazard higher than forecast. For more insight check out the latest Forecasters Blog.

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Synopsis: A series of slow moving frontal systems will move through the BC interior.Tonight: Cloudy with flurries, possible 5 to 10cm of precipitation, overnight freezing levels will drop close to valley bottom Winds light, gusting to moderate from the south west.Saturday: Cloudy with flurries, 5 to 10cm of precipitation expected, daytime freezing level around 1500m, No overnight freeze and freezing levels may go up to 1600m, winds light to moderate from the south west.Sunday: Cloudy with flurries, trace to 5cm of precipitation possible, freezing level may rise to 1400m, winds light, gusting to moderate from the south west.Monday:  Sunny with a few cloudy periods, no precipitation in the forecast, freezing levels rise  to 2500m and winds should be light to moderate from the south west.

Avalanche Summary

Reports of large avalanches have dropped off, but we are still getting reports of loose dry and loose wet avalanches from steep alpine terrain. One size 2.5 natural avalanche triggered by solar warming and several 1 to 1.5 avalanches. Sluffing in steep terrain is being reported on all aspects.A low probability, but high consequence avalanche problem exists in the Columbia regions. Highly destructive and unpredictable avalanches are possible during these spring conditions. Smaller avalanches have been reported stepping down to old, deeply buried weak layers and producing very large avalanches. Solar input is a big factor as spring progresses.  Watch out for large mature cornices!

Snowpack Summary

Recent warm temperatures have resulted in good settlement and bonding of the storm snow from earlier in the week, but wind slabs may still be touchy on north and east aspects.Three persistent weaknesses contribute to a highly variable snow pack with the possibility of triggering deeper instabilities. The mid-March sun crust/surface hoar layer down 50-80cm still has potential for human-triggering in isolated areas. The early-March crust/facet/surface hoar layer down around 80-120cm has become less susceptible to triggering by light loads, but still has the ability to produce large avalanches, we continue to hear reports of avalanches stepping down to this layer. The mid-February crust/facet/surface hoar layer is typically down at least 1.5m and direct triggering has become unlikely. However, large loads like cornices or smaller avalanches picking up mass might still trigger this layer and produce very large avalanches.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.