Avalanche Forecast

Issued: Apr 3rd, 2014 9:25AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Storm Slabs, Persistent Slabs and Deep Persistent Slabs.

bcorrigan, Avalanche Canada

Cariboos.

New snow amounts and rising temperatures are driving the hazard these days. Cornices will become weak as temperature rise.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Synopsis: A frontal systemÂ with an upper level trough is moving slowly onto the coast will bring clouds and precipitation inland.Friday: Cloudy with flurries, up to 20 cm of precipitation possible. No overnight freeze and freezing levels up to 1400m. Winds light, gusting to moderate from the south west.Saturday: Cloudy with flurries. Trace of precipitation in the forecast for the region, daytime freezing level around 1400m, overnight freezing levels will drop close to valley bottom, winds, light to moderate from the south west.Sunday: Cloudy with flurries. Possible 5 to 10 cm of precipitation, for the region, freezing levels around 1500m, winds, light gusting moderate to strong.

Avalanche Summary

Avalanche activity appears to have slowed down, but there were two reports of skier remote avalanches size 1.5 to 2, indicating that it's still possible to trigger reasonably large avalanches from a distance.Â One report of a cornice failure stepping down to a persistent weak layer producing a size 2 avalanche. Neighboring regions have reported large natural avalanches on north and east aspects. There is concern that weak layers will become more reactive with rising temperatures and solar warming. This spring, a low probability, high consequence avalanche problem plagues the Columbia regions. Highly destructive and largely unpredictable avalanches are possible right now.

Snowpack Summary

Convective squalls have produced 5 to 10 cm in the last 24 hrs throughout the forecast region. Previous storm snow continues to settle and bond. Suncrust from the last clear sunny days is now being buried by convective activity, wind slabs exist in lee terrain on NW through E aspects at tree line and into the alpine.Three persistent weaknesses now contribute to a highly variable, complex snowpack.A mid-March sun crust/surface hoar layer down 50-80cm has potential for human-triggering in select locations. New wind slabs may have been formed on this layer. An early-March crust/facet/surface hoar layer down around 80-120cm has become less susceptible to human-triggers, but still has the potential to produce large avalanches. We have reports of avalanches stepping down to this layer. A mid-February crust/facet/surface hoar layer that we've been watching is now down at least 1.5m and although direct triggering has become less likely, a large load like a cornice failure or smaller avalanches gaining mass could trigger this layer and produce very a large and destructive avalanche.

Problems

Storm Slabs

Recent storm snow and wind slabs may still be reactive to human triggers in select locations. Sun will increase the reactivity of the storm snow, especially on solar aspects, in the afternoon and sluffing can be expected in steep terrain.

Assess start zones carefully and use safe travel techniques.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Avoid regrouping in runout zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

Weak layers buried earlier this month remain reactive to light triggers on convex slopes, southern aspects, and steep alpine terrain. A small avalanche might trigger a deep persistent weak layer and result in a highly destructive avalanche.

Use conservative route selection, stick to moderate angled terrain with low consequence.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Cornices become weak with daytime heating. >

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Deep Persistent Slabs

Isolated large destructive avalanches are expected to continue. The variable nature of the problem makes it difficult to predict exactly when and where an avalanche will occur.New snow loading, sun and warm temperatures may wake up these layers.

Avoid large convexities or areas with a thin or variable snowpack.>Resist venturing out into complex terrain, even if you observe no obvious signs of unstable snow.>Local knowledge of slopes that have yet to avalanche is valuable for knowing which slopes to avoid.>Be aware of thin areas that may propogate to deeper instabilites.>Be aware of thin areas that may propogate to deeper instabilites.>Local knowledge of slopes that have yet to avalanche is valuable for knowing which slopes to avoid.>Resist venturing out into complex terrain, even if you observe no obvious signs of unstable snow.>Avoid large convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Apr 4th, 2014 2:00PM