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 Wind Slabs and Persistent Slabs.
MBender,
Avalanche Canada
Watch for new wind slab development at upper elevations. A persistent slab problem is still a consideration in sheltered terrain.
Summary
Confidence
Weather Forecast
SUNDAY Night: Cloudy with scattered flurries, accumulation 1-5 cm. Light to moderate southwest wind. Alpine high temperatures around -7 C. Freezing level at valley bottom.
MONDAY: Mix of sun and cloud. Light west and southwest wind. Alpine high temperature -4. Freezing level 1400 m.
TUESDAY: A mix of sun and cloud. Light west and southwest wind. Alpine high temperature -5. Freezing level 1400 m.
WEDNESDAY: Cloudy with sunny breaks and isolated flurries. Light to moderate northwest wind. Alpine high temperature -6. Freezing level 1300 m.
Avalanche Summary
Avalanche observations from the past week are limited to some reports of natural avalanches in the Barkerville area on Wednesday. Warm sunny weather likely caused a cycle of wet loose avalanches over the past few days.
Given the lack of recent field observations we remain uncertain about the likelihood of persistent slab avalanches. Since there was significant activity on these layers between Feb 23-28, we recommended remaining cautious because these types of weaknesses can take a long time to heal. Only consider pushing into bigger, steeper avalanche terrain if you are equipped to rule out the possibility of deeper weak layers in your local riding area.
Snowpack Summary
Up to 10 cm of new snow has accumulated above moist and crusty interfaces that formed during last Thursday's warm up. Deeper accumulations can be expected in lee terrain features as a result of southwest winds. High, shaded terrain will have a mix of soft snow and some old buried wind slabs.
In the last week of February multiple weak layers produced large avalanches, but we have little to no information about how these layers have trended since then. Recent weather patterns have likely helped these layers strengthen, but uncertainties are high.
Layers of concern include a 50-100 cm deep layer of facets that was buried in mid-February, a 50-150 cm deep layer of surface hoar from early February that was most prevalent at treeline (and existed as a facet/crust combination on steep south-facing terrain), and finally another persistent weak layer from late January that is now roughly 100-150 cm deep.
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
Problems
Wind Slabs
A bit of new snow and wind at upper elevations continue to build fresh thin wind slabs.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Uncertainties about buried weak layers warrants conservative terrain choices. There are several persistent weak layers 50-150 cm below the surface that have produced large natural and human triggered avalanches in the last week of February. We are uncertain whether time has helped these weaknesses heal or whether they are still reactive to human triggering.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 8th, 2021 4:00PM
