Cariboos Avalanche Forecast

Issued: Mar 1st, 2021 4:00PM

Tue Mar 2nd Current Conditions
Alpine Considerable Treeline Considerable Below Treeline Moderate
Wed Mar 3rd 2 Day Outlook
Alpine Considerable Treeline Moderate Below Treeline Moderate
Thu Mar 4th 3 Day Outlook
Alpine Considerable Treeline Considerable Below Treeline Considerable

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Persistent Slabs and Wind Slabs.

The snowpack in the Cariboos remains complex. You may not see obvious signs of instability, but persistent slabs are like sleeping dragons, and you really don't want to be the one to wake them up! Manage this problem by sticking to simple, low angle terrain.

Summary

Confidence

Moderate - Uncertainty is due to the complexity of the snowpack’s structure. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

MONDAY NIGHT - Mainly cloudy with a few flurries, 5-10 cm / strong southwest wind / alpine low temperature near -10 

TUESDAY - Mainly cloudy with a few flurries, up to 5 cm / strong southwest wind / alpine high temperature near -9 / freezing level 1200 m

WEDNESDAY - A mix of sun and cloud / moderate southwest wind / alpine high temperature near -4 / freezing level 1500 m

THURSDAY - Mainly sunny / moderate to strong south wind / alpine high temperature near -3 / freezing level 2200 m

Avalanche Summary

Multiple persistent weak layers in the snowpack may have reached a 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 size 2 human-triggered wind slab avalanche in the east of the region on Sunday. Check out the MIN report here.

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 last 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.

Last 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. 

There is about 50-100 cm of snow sitting on a persistent weak layer of facets that was buried in mid-February.

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. Recent test results also suggest that this layer is still a serious concern, and will propagate widely if triggered.

Terrain and Travel

  • Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
  • Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Avoid freshly wind loaded terrain features.

Problems

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible

Expected Size

2 - 3.5

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.

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible-Likely

Expected Size

1 - 2

Wind slabs are expected to be reactive in lee terrain with moderate to strong southerly winds in the forecast. Previous variable wind direction means that wind slabs may be found on all aspects. The most reactive ones are likely to be found on northerly aspects.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Valid until: Mar 2nd, 2021 4:00PM

Forecast Trend

The latest forecast danger ratings, broken down to elevation. See how an elevation is trending.