Avalanche Forecast
Issued: Dec 24th, 2019 3:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
ghelgeson,
Avalanche Canada
Avalanche activity has slowed over the last 48 hours, but the recent cycle was so large and destructive that conservative terrain selection remains prudent. It's nearly impossible to trust a snowpack that has recently produced size 3.5 avalanches.
Summary
Confidence
Weather Forecast
We’re entering a rather quiet weather period with coolish temps and no significant snowfall expected, at least through boxing day. The region should see winds pick up later in the week and there is potential for a small shot of snow Thursday night.
CHRISTMAS EVE: Freezing level at valley bottom, light variable wind, no significant precipitation expected.
CHRISTMAS: Scattered cloud cover, freezing level near valley bottom, light northwest wind, no significant precipitation expected.
BOXING DAY: Scattered cloud cover in the morning building to overcast by sundown, freezing level at valley bottom, moderate to strong south/southwest wind, trace of snow possible during the day, potential for 5 to 10 cm by Friday morning.
FRIDAY: Broken cloud cover, freezing level at valley bottom, moderate to strong west/southwest wind, trace of snow possible during the day.
Avalanche Summary
The recent storm was a significant one, and there is a great deal of uncertainty at this time as to how quickly the snowpack will gain strength. Avalanche occurrences are beginning to taper, but recent avalanches have been very large. Patience and conservative terrain selection is the name of the game right now.
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 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 have seen 60-100 cm of new snow since Thursday night. Storm slabs are likely widespread and may be reactive to human triggering.
There is anywhere from 100-160 cm of snow on top of a widespread layer of large, feathery surface hoar crystals. This layer is suspected to have been responsible for numerous recent avalanches and it may continue to be reactive to human triggers.
A weak layer that formed in late November is now over 160 cm deep. This is the layer of concern relating to the listed persistent slab avalanche problem. The weak layer may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect.
Terrain and Travel
- Make conservative terrain choices and avoid overhead hazard.
- Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
- Be aware of the potential for large avalanches due to the presence of a buried crust.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Problems
Storm Slabs
Storm slabs could still be triggered by humans, especially in wind loaded areas.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
There is a weak layer of surface hoar down 100-160 cm. Numerous recent avalanches have occurred on this layer and human triggering is a possibility.
Another weak layer that formed in late November is now down over 170 cm. This layer could be triggered from shallow snowpack areas, and it is also possible for avalanches triggered on the shallower layer to step down to this layer, resulting in very large avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 25th, 2019 5:00PM
