Avalanche Forecast
Issued: Mar 5th, 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.
istorm,
Avalanche Canada
Wind slabs are the primary avalanche problem but don't forget about deeper layers in shallow snowpack areas and in eastern areas of the region. Persistent layers are trickier to manage.
Summary
Confidence
Weather Forecast
Friday Night: Temperatures starting to cool. Trace to 5 cm snow. Strong SW winds continue.
Saturday: Wind veers toward the west and starts to ease (to moderate) late in the day. Trace to 10 cm snow. Overcast. Temperatures continue to cool with all elevations finally falling below freezing.
Sunday: Quieter pattern with southwest winds easing to light, treeline temperatures around -5 C, and little in the way of new snow.
Monday: Similar to Sunday but winds shifting to NW and increasing
Avalanche Summary
The warm temperatures this week triggered loose wet avalanches on solar (south throug west) aspects. Strong winds triggered wind slabs naturally up to size 2 and explosive controlled avalanche (near Pine Pass) up to size 3.
Snowpack Summary
We have a range of accumulated new snow totals since last weekend: somewhere around 90 cm in Pine Pass (the deepest), down to something like 30 or 40 cm in Kakwa. The key point is there's recent loose snow at higher elevations available for wind transport. Strong south to west winds in exposed areas have scoured some slopes and build windslabs on others. Freezing levels reaching treeline Thursday with +3 C at Renshaw, =8 C in Kakwa on the east side of the divide.
About a metre of snow covers a weak layer of facets (and potentially surface hoar) from mid February and a slightly deeper, widespread persistent weak layer from late January/early February that consists of surface hoar. It is most prevalent around treeline elevations, but likely reaches into the alpine and in openings below treeline too. These layers are both significantly shallower in the east of the region.
Terrain and Travel
- Avoid freshly wind loaded terrain features.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Wind Slabs
The recent storm created wind slabs across exposed leeward and crossloaded terrain.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Our persistent slab problem appears to have been put to rest in deep snowpack areas in the west of the region, but on the eastern slopes (e.g. Kakwa) this is less certain. The most likely triggers are surface avalanches stepping down, cornice fall, or the weight of a machine hitting a thin-spot.
Aspects: All aspects.
Elevations: Treeline.
Likelihood
Expected Size
Valid until: Mar 6th, 2021 4:00PM
