Avalanche Forecast

Issued: Dec 23rd, 2014 8:10AM

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

rbuhler, Avalanche Canada

Northwest Inland.

This forecast was created using limited field data. If you are out in the mountains, please consider sending us your observations or posting on our new website.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Conditions on Wednesday will be unsettled as the storm is replaced by a ridge of high pressure that will establish itself for Thursday and Friday. By Wednesday afternoon the precipitation should have ended but scattered flurries are possible. Freezing levels should drop to near valley bottom and alpine winds should taper off to light from the NW. A mix of sun and cloud is expected for Thursday with freezing levels around valley bottom and light alpine winds. By Thursday afternoon, a weak disturbance may bring light scattered flurries. Friday should be mostly dry and cloudy with light alpine winds.

Avalanche Summary

We received a report on Sunday from the Hankin area of a natural size 1 slab avalanche. This occurred on a north aspect at treeline. The crown depth was around 20cm and it failed on the most recent rain crust. Check out the report here: http://goo.gl/WdmvxL

Snowpack Summary

The new snowfall is adding to the weekend storm slab which is typically between 20-40 cm thick. Very strong winds have transported snow in the alpine and at treeline into pockets of windslab that may not be well bonded to the old surfaces. Below the new snow you'll likely find wind-scoured surfaces and old wind slabs in exposed terrain, and settled storm snow closer to treeline. Near the base of the snowpack, weaknesses such as the mid-November crust-facet layer are still of concern. I'd use extra caution around steep, unsupported high elevation terrain as avalanches at this interface could propagate over wide distances.

Problems

Storm Slabs

The new storm snow is adding to the storm loading from the weekend. Strong winds are loading leeward slopes in exposed terrain.

Travel in avalanche terrain is not recommended with current conditions.>Use conservative route selection, stick to low angled terrain with low consequence.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

Deeply buried weak layers may release during periods of high loading from new snow and wind. Triggering of these deep layers is most likely from shallow snowpack areas such as areas around rock outcrops.

Be aware of thin areas that may propogate to deeper instabilites.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Dec 24th, 2014 2:00PM