Issued: Mar 31st, 2023 4:00PM
The alpine rating is Wind Slabs and Deep Persistent Slabs., the treeline rating is , and the below treeline rating is Known problems include
Make conservative terrain choices while we see how the snowpack reacts to the storm. New snow and wind are making wind slab avalanches possible.
On Thursday, south of Valemount, several small (size 1.5) naturally triggered avalanches were reported on SE-SW aspects in the alpine. They occurred on slopes facing the sun during the warmest part of the day.
On Wednesday, west of McBride, a large (size 3.0), naturally triggered, cornice avalanche was reported on a north aspect in the alpine. It travelled 600 m down the slope and entrained a large amount of loose snow.
Up to 10cm of soft snow sits over a thin crust on steep slopes facing the sun right up into the alpine. Snow that fell earlier in the week has been redistributed by northeast winds. On high, north-facing terrain, wind slabs may sit over facets and surface hoar.
The mid-snowpack is generally strong. There continues to be a weak layer of facets from November at the base of the snowpack. This layer remains a concern in rocky, shallow, or thin to thick snowpack areas at treeline and above.
Mostly cloudy. 0-5 cm of snow expected. Light southwest ridgetop wind, trending to moderate at higher elevations. Freezing level at valley bottom. Treeline high around -5°C.
Partly cloudy. 5-10cm of snow expected. Light southwest ridgetop wind, trending to moderate west at higher elevations. Wind may die off mid-day, and pick back up from the northwest in the afternoon. Freezing level rising to 1200 m. Treeline high around -5°C.
Mostly cloudy. 0-2 cm of snow expected. Light variable wind. Freezing level at valley bottom in the morning, rising to 1200 m.
Partly cloudy. 0-2 cm of snow expected. Light northwest wind. Freezing level at valley bottom in the morning, rising to 1300 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Expect slab conditions to change drastically as you move into wind exposed terrain.
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
- Closely monitor how the new snow is bonding to the crust.
- Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.
Up to 10cm of fresh snow has likely been redistributed by moderate southwest wind. Expect to find deeper, reactive pockets of windslab on leeward slopes.
On any aspect except north, these slabs will be sitting on a refrozen crust formed by the recent sun and warm temperatures. It will be easier to cause an avalanche where a slab forms over this crust.
Aspects: North, North East, East, South East, North West.
Deep Persistent Slabs
A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's depth. Suspect terrain for human triggering includes steep, shallow, and rocky terrain where the snowpack transitions from thin to thick.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Valid until: Apr 1st, 2023 4:00PM