Avalanche Forecast

Issued: Feb 13th, 2014 3:00PM

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

Alberta Parks matt.mueller, Alberta Parks

Lots of change out there today, and more to come tomorrow. It's a  good time to keep the head up and be aware of changing snow conditions. Cautious terrain choices are recommended. Ice climbers respect terrain traps, dry avalanches are likely.

Summary

Confidence

Good

Weather Forecast

The snow is expected to taper overnight, before another round starts mid day friday. The winds will also decrease, but will remain at the perfect level for slab development. Wind directions will vary locally, but a prevailing SW-S flow will be the main theme. Temperatures will remain similar today. A daytime high of -4 at valley bottom.

Avalanche Summary

Field teams remoted a sz2 from 100m away this afternoon. The terrain was a 40-45 degree unsupported roll with a variable snow pack at the low alpine elevation range. The avalanche involved only the storm snow, the failure plain was the facet layer from the cold snap. A natural sz2 was also visible in an alpine bowl to the west.

Snowpack Summary

At upper treeline elevations we have had 42cm's of snow in the last 48hrs. This new snow has come in two separate storm events. The upper snow pack has a storm weakness (storm shear) that is down about 20cm's (depending on the area). The upper layer is slightly stiffer (due to wind) which will create a short term avalanche problem in itself. A larger concern is the general storm interface down 42cm's. The quality of the bonding within these layers is spotty, and generally suspect. A related concern is in the thinner areas. Lots of whumphing and cracking where the base has no structure or support. The general summary is it is a very touchy upper snowpack sitting a weak facetted base. At lower elevations, the storm snow is less wind effected and generally bonding well to itself, and other layers. \

Problems

Storm Slabs

An icon showing Storm Slabs
With the combination of moderate winds and a relatively warm storm, wind slabs are developing rapidly. Today saw slabs develop, and react within an hour of being  wind exposed.  Assess  the snowpack as a whole when going from treeline to alpine.
Avoid freshly wind loaded features.>Avoid convexities or areas with a thin or variable snowpack.>Make observations and assess conditions continually as you travel.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
The new load is a concern with this layer. Forecasters are unsure of how the basal layers will handle the rapid load. LOTS of whumphing and cracking on those lower layers today. Assess snowpack depth by probing to get a feel for what's beneath you.
Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Feb 14th, 2014 2:00PM