Avalanche Forecast

Issued: Nov 29th, 2018 4:55PM

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

jsmith, Avalanche Canada

North Columbia.

There is a lot of uncertainty with the reactivity of the buried surface hoar layer down 40-80 cm. Human triggered avalanches are more likely at treeline and sheltered locations in the alpine where this weak layer exists. New forecaster blog HERE.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

Overnight THURSDAY: Cloudy with isolated flurries / Alpine Low -9 / Light, southwest wind / Freezing level 300 m.FRIDAY: Cloudy with isolated flurries / Alpine high -9 / Light, southwest wind / Freezing level 700 m.SATURDAY: Mostly cloudy / Alpine high -10 / Light, northeast wind / Freezing valley bottom.SUNDAY: Mix of sun and cloud / Alpine high -10 / Light, northwest wind / Freezing level valley bottom.

Avalanche Summary

No avalanches were reported in this region on Wednesday. However, we currently have very few observations from within this region. Please post your observations to the Mountain Information Network (MIN). Although not in this region, a notable size 3, human triggered avalanche was reported in the South Columbia region on November 24th. The avalanche reportedly occurred on a northwest aspect, on a lee feature in the alpine and likely ran on a crust near the bottom of the snowpack. The full report can be found on the Mountain Information network. Click here to read the report

Snowpack Summary

Recent storm snow amounts range from 40-90 cm. This new snow sits on top of a weak layer of surface hoar (feathery crystals) and sun crust on steep south facing slopes. The surface hoar is most pronounced at treeline, but it may be found in sheltered alpine areas.At the base of the snowpack is a crust that formed in late October. There have been no recent reports in this region of reactivity on this layer.Total snowpack depths vary greatly with elevation. Recent reports show depths of 120-210cm in the alpine, 80-150 cm at treeline and 10-120 cm below treeline.

Problems

Persistent Slabs

Be especially cautious with this buried weak layer in the Treeline elevation band, on large open slopes that have a deep enough snowpack to bury all the bushes and make the slope smooth. It may also be present in sheltered, N. facing alpine slopes.

Start in conservative terrain while you gather additional information about the snowpack.Use small slopes with no consequence to test for the presence of the buried weak layer.Watch for signs of instability such as ‘whumphing’, cracking, and evidence of recent avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Valid until: Nov 30th, 2018 2:00PM