Avalanche Forecast
Issued: Dec 24th, 2020 8:00AM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
Percy Woods,
The storm has passed but the persistent weak layers linger within human triggering range. Avalanches triggered on these layers may be large and of high consequence.
Summary
Weather Forecast
Sunny with cloudy periods and no precipitation.
Alpine temperatures reaching a high of -5 C accompanied by moderate SW winds.
Freezing level around 900 metres.
Look for an alpine temperature inversion.
Cloudy with sunny periods Christmas day along with a trace of precip and warming temperatures.
Snowpack Summary
120cm snow in the past week along with warm temps and strong S-SW winds culminating in slab formation at all elevation bands. Dec 13 surface hoar/facets are down 120cm+ and the Dec 7 crust/surface hoar layer is down 140cm+. The Nov 5 crust lingers near the base of the snowpack and several avalanches over the storm period stepped down to it.
Avalanche Summary
Avalanche control just west of Glacier Park produced slides to size 4 yesterday. Monday evening artillery and RACS controlled avalanches averaged size 3. Natural avalanches to size 3.5 occurred up Connaught creek Monday night. Natural activity has decreased with the passage of the storm. Human triggering remain likely in wind effected terrain.
Confidence
Problems
Wind Slabs
120cm of storm snow fell in the last week with mild temperatures and strong S/SW winds. Post storm strong Northerly winds reverse loaded southerly aspects too, so expect slab formation on all aspects especially in the alpine and exposed areas of TL.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
- Watch for reverse loading created by N-NE winds.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
The December 7th surface hoar/crust paired with the December 13th surface hoar has made an excellent weak layer for LARGE slab avalanches. Storm or wind slabs have lots of potential to step down to this layer.
- Be aware of the potential for wide propagations.
- Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 25th, 2020 8:00AM
