Avalanche Forecast
Issued: Apr 11th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Cornices and Loose Wet.
ahanna,
Avalanche Canada
The spring sun can pack a punch and quickly initiate loose wet avalanche activity on steep slopes. Be ready to back off as the snow surface becomes moist. Lingering wind slabs may remain reactive to human triggers on lee features at alpine and treeline elevations.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
A ridge of high pressure sets up over the province bringing sunny, dry weather. Freezing levels are forecast to steadily rise through the week.
Sunday night: Partly cloudy. Light wind switching east. Alpine temperature around -9. Freezing level valley bottom.
Monday: Sunny. Light to moderate east wind. Alpine temperature around -5. Freezing level 1600 m.
Tuesday: Sunny. Moderate east ridgetop wind. Alpine temperature around -2. Freezing level 2000 m.
Wednesday: Sunny. Moderate to strong east ridgetop wind. Alpine temperature around +1. Freezing level 2800 m.
Avalanche Summary
We have not received any reports of avalanche activity since Wednesday when the North Rockies Field team reported and wind slab size 1 from an East aspect at treeline. Since Friday wind slabs have been reported to be stubborn.
In neighboring North Columbia region, wind slabs have shown quite limited reactivity in the last couple of days, the odd ski cut producing size 1-1.5. A couple of natural cornice failures size 2.5 did not trigger slabs on slopes below.
Snowpack Summary
20-40 cm of recent snow may have formed pockets of wind slab on leeward slopes and behind terrain features. On North aspects in the alpine, the recent snow sits on dry wintery snow surfaces and possibly surface hoar on wind-sheltered slopes. Elsewhere, it sits on a series of melt-freeze crusts on all aspects below 1900 m and southerly aspects to mountain top. Reports indicate snow is bonding well at these interfaces.
The recent warm weather is expected to have helped old persistent weak layers heal, including a few crusts buried over the last month as well as a facet layer 150 cm deep from the mid-February cold snap.
Terrain and Travel
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
- Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Problems
Wind Slabs
Lingering pockets of wind slab may be triggerable in unsupported terrain features.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Cornices are especially fragile this time of year, especially when the sun is out. Cornice falls are dangerous on their own and they can also trigger slabs on slopes below.
Aspects: North East, East, South East.
Elevations: Alpine.
Likelihood
Expected Size
Loose Wet
Surface snow can quickly lose cohesion and become unstable with solar warming during the day. Avoid exposing yourself to terrain where a small wet loose release could have big consequences.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Apr 12th, 2021 4:00PM
