Avalanche Forecast
Issued: Feb 27th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Storm Slabs.
kdevine,
Avalanche Canada
A complex snowpack can be safely managed by sticking to simple terrain. With persistent slab avalanches, there are often no obvious signs of instability. When triggered, these avalanches are large and destructive.
Summary
Confidence
Weather Forecast
SATURDAY NIGHT - Mainly cloudy with flurries, 5-10 cm / moderate southwest wind / alpine low temperature near -14
SUNDAY - Mainly cloudy with scattered flurries / strong west wind / alpine high temperature near -6 / freezing level 1500 m
MONDAY - Mainly cloudy with flurries, 5 cm / strong southwest wind / alpine high temperature near -6 / freezing level 1500 m
TUESDAY - Mainly cloudy / strong southwest wind / alpine high temperature near -9 / freezing level 1000 m
Avalanche Summary
Multiple persistent weak layers in the snowpack may have reached their tipping point. Avalanches on these layers will be large and destructive. The only way to truly manage this problem is to stick to simple terrain.
There was a report of a natural size 2.5 avalanche running full path in the Dore River area on Thursday. A MIN report about this can be viewed here.
Several natural and human-triggered avalanches size 2-3.5 were reported on Tuesday near Valemount at alpine and treeline elevations. One very large human-triggered avalanche was initiated from a wind-loaded start zone at the top of a large alpine feature. It propagated for hundreds of meters along a ridge and ran to valley bottom. Thankfully the rider was able to escape unharmed.
On Tuesday, there was a fatal avalanche just outside of the region, northeast of Valemount in Swift Creek. The avalanche was a size 3.5 and is suspected to have failed on the late January persistent weak layer. The report can be found here.
Snowpack Summary
The snowpack in the Cariboos is currently complex, with multiple persistent weak layers.
The region has received 40-90 cm of fresh snow in the past week. There are deep wind deposits in lee features at upper elevations. The recent snow sits on a persistent weak layer of facets that formed on the surface during the early to mid-February cold snap.
There is now 80-180 cm of snow above another persistent weak layer from early February which is composed of surface hoar. This layer is most prevalent at treeline and below treeline. On steep south-facing terrain, this layer may consist of facets on a sun crust.
Yet another persistent weak layer from late January exists down 90-200 cm. There have been very few recent reports of avalanches on this layer, however, there have been several large avalanches on this layer in the neighboring North Rockies region recently.
Terrain and Travel
- Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Be aware of highly variable recent wind loading patterns.
Problems
Persistent Slabs
40-80 cm of recent storm snow sits on a layer of weak, sugary facets. At upper elevations, the recent snow has been blown into reactive slabs in lee features. Recent avalanches have propagated widely and surprised riders.
Two more persistent weak layers are buried between 80-200 cm. These have not produced recent avalanches in the region that we know of, but have been responsible for several recent large avalanches in the neighboring North Rockies region, including two fatal avalanches in the past week.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Storm Slabs
Storm slabs may continue to be reactive, especially in wind-loaded areas.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 28th, 2021 4:00PM
