Avalanche Forecast
Issued: Mar 18th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Loose Wet and Deep Persistent Slabs.
GL,
Avalanche Canada
The region is trending towards spring like conditions. Start early and finish early as the sun is having the strongest effect typically by mid-afternoon. It is wise to choose ice climbs with no overhead hazard and least amount of overall sun exposure.
Summary
Confidence
Avalanche Summary
On Saturday, no new avalanches were noted in Marmot Basin backcountry. On Friday, Banff Park's helicopter bombing created some large avalanches in the Mt. Whymper area. Friday's Maligne patrol did not observe anything significant. Same for Friday's Icefield patrol except for surface pinwheeling and small loose wet below treeline. From March 14-16, the Icefields parkway had numerous medium to large slab avalanches in the alpine on steep rocky features. Some were cornice triggered.
Don't forget to post avalanche observations to the MIN.
Snowpack Summary
A suncrust has formed on solar aspects at all elevations. This caps off the 15-20cm of new snow from March 13th. Moderate SW winds after March 13th created pockets of windslab on lee aspects. Approximately 20-30cm down is a buried sun crust at low elevations on steep southerly slopes and a surface facet layer in sheltered terrain. The mid-pack is 40 to 80cm of supportive snow. Near the ground it is generally weak with large facets and depth hoar.
Weather Summary
Sunday will be sun and cloud, -3 °C, light wind, and 1900 metres freezing level. Monday will be similar with 1600 metres freezing level. Tuesday will be a repeat of Monday with 2000 metres freezing level. No change for Wednesday.
Detailed weather forecasts from Avalanche Canada: https://www.avalanche.ca/weather/forecast
Terrain and Travel Advice
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- It’s possible for avalanche danger to remain elevated into the early evening hours.
Problems
Wind Slabs
March 13th 20cm of storm snow accompanied by moderate southwest winds has created wind slabs in the alpine and on isolated features at tree line. Wind slabs will become more reactive on sun exposed slopes as temperatures rise. Even a small wind slab may wake up the deep persistent problem.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Loose snow avalanches will be vary from wet to dry depending on aspect and elevation. If the terrain is steep and protected from wind, a loose snow avalanche is possible. Even these smaller avalanches may trigger the deep persistent slab in isolated spots.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The bottom of the snow pack is inherently weak with well developed Facets and Depth Hoar. Wind slab avalanches have stepped down to the deep persistent slab since the last storm meaning large triggers can influence this basal weakness. The likelihood is slowly increasing for this high consequence avalanche problem.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 19th, 2023 4:00PM
