Avalanche Forecast

Issued: Apr 4th, 2014 9:51AM

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

bcorrigan, Avalanche Canada

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.

Summary

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

Storm snow may be reactive to human triggers on wind loaded features. A small avalanche could easily injure a rider, or trigger something larger. Solar input is important, especially in the afternoon. Large mature cornices can fall at any time.

Minimize exposure to sun exposed slopes when the solar radiation is strong.>Be cautious as you transition into wind affected terrain.>Pay attention to overhead hazards like cornices.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

Weak layers buried earlier this month remain reactive to rider triggering on convex slopes, south aspects, and steep alpine terrain. A small avalanche might gain enough mass to trigger a persistent weakness and trigger a highly destructive avalanche.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Minimize exposure to sun exposed slopes when the solar radiation is strong.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Deep Persistent Slabs

Highly destructive avalanches continue to occur. The variable nature of this problem makes it difficult to predict exactly when and where a big avalanche might happen. A cornice failure, or sun and warm temperatures could 'wake-up' weak layers.

Avoid large convexities or areas with a thin or variable snowpack.>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.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Apr 5th, 2014 2:00PM