Avalanche Forecast
Issued: Jan 16th, 2018 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs.
Grant Statham,
Parks Canada
Avalanche control on Mt. Dennis produced large avalanches that ran over the ice climbs and crossed the Field Back Road. Be very careful at treeline in Little Yoho. Natural avalanches are unlikely but human triggered avalanches are likely.
Summary
Weather Forecast
The ridge of high pressure is breaking down and a Pacific storm will cross the region starting Wednesday afternoon. Wednesday itself will be colder (-4 to -10) with winds picking up from the west and snow starting in the afternoon. Expect up to 15 cm by the end of the storm on Thursday afternoon.
Snowpack Summary
Recent warm temperatures aloft have settled the upper snowpack, with suncrust formed on S and W aspects. 30-50cm of snow sits over the Dec.15 persistent weak layer of facets and surface hoar. We are concerned about this layer at treeline in Little Yoho where the layer is producing easy to moderate snowpack test results and widespread whumphing.
Avalanche Summary
Tuesday's avalanche control on Mt. Dennis (above the ice climbs) produced large (size 3) avalanches running over the popular ice climbs with debris and trees reaching the Field Back Road. These were the largest results from a 2-day, park wide avalanche control mission which confirms our suspicion of dangerous conditions at treeline in Little Yoho.
Confidence
Problems
Persistent Slabs
This layer is a concern mainly at treeline around Field, Emerald Lake and Little Yoho - this is a very specific band. Natural avalanches are unlikely but human triggered are likely - watch overhead hazard BTL; avalanches can run into the forest.
Avoid open slopes and convex rolls at treeline where buried surface hoar may be preserved.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 17th, 2018 4:00PM
