Avalanche Forecast
Issued: Dec 25th, 2019 2:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs.
ghelgeson,
Avalanche Canada
Avalanche activity has waned, but a slab up to 160 cm in depth may remain sensitive to human triggering, especially in more aggressive terrain. You can't feel a problem like this under your track or skis so the solution is in our terrain selection, keep it relatively simple.
Summary
Confidence
Weather Forecast
The most recent weather model runs are showing very little precipitation through the end of the year aside from small dribs and drabs. Looks like the wind will begin to pick up out of the south/southwest on Thursday, especially in the higher alpine terrain features.
WEDNESDAY NIGHT: Freezing level at valley bottom, light west/southwest wind, no significant precipitation expected.
BOXING DAY: Clear skies at dawn with increasing cloud cover throughout the day, overcast by sundown. Freezing level at valley bottom, calm/light wind up to at least 2000 m with potential for moderate to strong south/southwest wind in the high alpine late in the day, trace of snow possible during the day, potential for 2 to 8 cm by Friday morning.
FRIDAY: Broken cloud cover, freezing level at valley bottom, calm/light wind at most elevations, moderate west/northwest wind in the alpine, trace of snow possible during the day.
SATURDAY: Scattered cloud cover at dawn building to broken by sundown, freezing level at valley bottom, calm/light wind at most elevations, potential for moderate to strong southerly wind in the alpine, no precipitation expected.
Avalanche Summary
The recent storm was a significant one and there is now a great deal of uncertainty as to how quickly the snowpack is regaining strength. Avalanche activity is tapering, but avalanches during and just after the storm were spectacularly large and destructive.
Aside from sluffing in steep terrain, no new avalanche activity was reported from Tuesday.
Avalanche activity on Monday was sharply reduced from the previous days, but there was still a size 2.5 avalanche triggered by a snowcat on a NE facing slope at 2500 m. A small skier controlled avalanche was also reported from a northeast facing slope at 2300 m.
Between last Thursday and Sunday there were numerous reports of natural, human and explosive triggered avalanches up to size 3.5. Many of these were triggered remotely.
Snowpack Summary
The South Columbias received 60 to 100 cm from last weekend's big storm which is slowly settling into a slab. There is now anywhere from 100 to 160 cm of snow resting on a widespread layer of large, feathery, surface hoar which we're calling the "December 11th Surface Hoar." Activity on this interface is tapering dramatically, but this layer produced some very large natural avalanches during and just after the storm.
A combination of surface hoar, crust & facets formed in late November is now over 170 cm deep. This layer is likely trending toward dormancy.
Terrain and Travel
- In times of uncertainty conservative terrain choices are our best defense.
- Start with simple terrain and gather information before thinking about more committing features.
- Caution around convexities or sharp changes in terrain.
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
Problems
Persistent Slabs
All of the old storm snow is slowly settling into a slab which rests on weak surface hoar 100 to 160 cm below the surface. Natural avalanche activity has waned, but human triggering remains possible, especially in more challenging/complex terrain. This isn't the kind of avalanche problem you can feel under your skis, track or feet, it's far too deep for that. The only way to manage a problem like this is to choose well supported terrain free of overhead hazard.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 26th, 2019 5:00PM
