Avalanche Forecast
Issued: Mar 7th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Cornices.
mconlan,
Avalanche Canada
Buried weak layers remain possible to be triggered by riders, where they exist. Cornices and sun-exposed slopes will deteriorate during the heat of the day, potentially increasing the likelihood of avalanche activity.
Summary
Confidence
Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
SUNDAY NIGHT: Cloudy with light snowfall then clearing, accumulation 2 to 5 cm, 30 km/h southwest wind, alpine temperature -8 C.
MONDAY: Clear skies, 10 km/h northeast wind, alpine temperature -6 C, freezing level rising to 1500 m.
TUESDAY: Mix of sun and cloud, 20 km/h southwest wind, alpine temperature -6 C.
WEDNESDAY: Mix of sun and cloud with afternoon snowfall, accumulation 2 to 5 cm, 20 km/h west wind, alpine temperature -8 C.
Avalanche Summary
No avalanches were observed on Saturday or Sunday, besides some small loose dry out of steep alpine terrain. The most recent avalanche activity was observed on Friday, where wet loose avalanches, cornices, and persistent slab avalanches were triggered by riders and explosives.
Snowpack Summary
Previous warm air temperature followed by a re-freeze created a crust on the snow surface in many areas, which is covered by a dusting of fresh snow. Dry snow may still be found on north aspects at upper elevations. Wind slabs are likely still present on northerly aspects in the alpine and at treeline elevations.
Up to 50 cm of snow sits above a variety of old interfaces that formed in mid-February. There is 60-100 cm sitting on a persistent weak layer that was buried in late January. These interfaces are mostly made up of sugary faceted grains, hard wind pressed snow, feathery surface hoar in wind-sheltered locations, and a melt-freeze crust on steep solar aspects. Periodic avalanches continue to be triggered on these layers. Check out this MIN for photos of the positioning of the layers in the snowpack.
Terrain and Travel
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Problems
Persistent Slabs
Two persistent weak layers exist in the snowpack:
- The upper layer is buried 30 to 50 cm and primarily consists of sugary faceted grains.
- The deeper layer is buried 60 to 100 cm. This layer consists of surface hoar, faceted grains, and/or a hard melt-freeze crust. The problem has been most prevalent around treeline and in openings below treeline, but also reaches into the lower alpine.
These layers could be triggered by riders anywhere they still exist. A warm and sunny Monday may increase the likelihood of triggering these layers.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Cornices will weaken with sunny skies and relatively mild air temperature. The snow on sun-exposed slopes may also weaken, so use caution during the heat of the day.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 8th, 2021 4:00PM
