Avalanche Forecast

Issued: Mar 26th, 2015 9:33AM

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

swerner, Avalanche Canada

Cariboos.

A complex and unpredictable snowpack exists. Avalanche Canada has released a Special Avalanche Warning for this region. Check out the details here: http://www.avalanche.ca/news/VRHTjCUAADQcpVdL/spaw-150324

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Unsettled warm, wet and windy conditions will continue through the weekend. As the stationary cold front slowly slides southward cooler air will replace the warm air overnight on Friday before another storm sets up on Saturday. On Friday, light precipitation up to 10 mm are expected with strong SW ridgetop winds and freezing levels rising to 2500 m. Freezing levels will drop overnight Friday to 1200 m then rising to 2000 m on Saturday. Ridgetop winds will blow moderate to strong from the SW-W and light convective precipitation will continue. On Sunday, precipitation amounts 3-12 mm are expected with ridgetop winds strong from the west. Freezing kevels will stay steady around 2000 m.

Avalanche Summary

On Wednesday, no new avalanches were reported. Earlier in the week, widespread natural and human triggered avalanches were reported up to size 2.5. With forecast warm, wet and windy weather widespread natural avalanche activity is likely. Human-triggered storm slabs and persistent slabs remain a serious concern, especially in steep alpine terrain. Remote triggering slab avalanches from afar also remain a concern. There is currently a Special Avalanche Warning for this region through the forecast period. For more technical information regarding the fatalities last weekend go here: old.avalanche.ca/cac/library/incident-report-database/view/12b2631a-5b7f-4f0e-a2d8-c6f89bfb494d.

Snowpack Summary

New snow up to 20 cm at higher elevations has added to the 40-60 cm of dense storm snow which sits over the mid-March interface. This buried persistent weak layer is comprised of a series of crusts, wind affected surfaces, and old wind slabs. Digging deeper is the mid- February persistent weak interface which is now down 80-120 cm and continues to be very reactive, producing very large and destructive avalanches. In exposed terrain, strong SW winds had redistributed the new snow into wind slabs on leeward features. From 2000 m down, the upper snowpack has become moist or wet, and has seen no significant re-freeze overnight.

Problems

Storm Slabs

Rising temperatures, wind, snow and rain are likely increasing the reactivity of the storm slabs. Natural avalanches and human triggered avalanches are likely. These slabs may be moist or wet at lower elevations.

Use conservative route selection, stick to moderate angled terrain with low consequence.>Avoid wind loaded features at upper elevations.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

The persistent weak layer buried mid-February is down up to 80-120 cm below the surface and has been the culprit of many large avalanches recently. Smaller avalanches could easily step down to this layer.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for wide propagations and remote triggering from far distances away.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

3 - 6

Loose Wet

Rising freezing levels and an extended period of warm temperatures will likely deteriorate the upper snowpack, resulting in loose wet avalanche activity.

Watch for clues, like natural avalanche activity, sluffing off of cliffs, moist/ wet snow surfaces, and snowballing. These are indicators that the snowpack is warming up and deteriorating.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Valid until: Mar 27th, 2015 2:00PM