Avalanche Forecast

Issued: Feb 14th, 2016 7:25AM

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

rbuhler, Avalanche Canada

Northwest Inland.

Benign weather on Monday should lower the hazard throughout most of the region.The hazard may be higher than posted in the far north of the region where buried weak layers may still be reactive to human-triggering.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Tuesday

Weather Forecast

A ridge of high pressure is expected to keep the region mostly dry on Monday. Freezing levels are expected to stay below 900m with light alpine winds. A storm system is expected to reach the region on Monday evening or overnight and should continue through Tuesday. 5-15cm is expected between Monday evening and Tuesday afternoon. Freezing levels are forecast to reach around 1000m and alpine winds are forecast to be moderate from the southwest. Wednesday is expected to be mainly dry with freezing levels below 700m and light alpine winds.

Avalanche Summary

On Saturday, a natural size 1.5 wind slab avalanche was reported on a west aspect at 2200m elevation which was 20cm thick. No new avalanches were reported on Friday. On Thursday in the far north of the region, a skier accidently triggered a size 2 persistent slab avalanche on a northwest aspect at 1650m and explosives triggered a size 2.5 persistent slab on a northeast aspect at 1400m. These both failed on the early January surface hoar layer down 100-150cm. Wind slabs are expected to remain reactive to human-triggering on Monday in steep, unsupported leeward features and around loaded convexities.Â In the far north, deeply buried persistent weak layers may still be reactive to large triggers.

Snowpack Summary

Recent snowfall and mostly southwestern winds have formed wind slabs in the leeward features in the alpine and at treeline. Storm snow from last week has settled due to recent warm temperatures. There may be a buried layer of surface hoar in the top 30 cm of the snowpack from early February, this layer was found at Hankin, but has not been widely reported. Crusts may be developing at mid-elevations as the freezing level slowly descends. The early January persistent weak layer of buried surface hoar is down 50-80 cm in most of the region, but may be down a metre or more in the deeper snowpack areas in the southwest of the region. Shallow snowpack areas in the east and north of the region may have a weak base layer of facetted snow on or just above the ground.

Problems

Wind Slabs

Recent snow and strong winds have formed wind slabs on mainly north to easterly aspects at treeline and in the alpine.

Avoid freshly wind loaded features.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

Buried weak layers are still reactive in the snowpack, especially in the far north of region, and have the potential to produce very large avalanches. Thin spot triggering, cornice releases, and smaller avalanches all have the potential to step down.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, widely propagating avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Feb 15th, 2016 2:00PM