Avalanche Forecast
Issued: Feb 19th, 2021 4:00PM
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
If you cannot identify avalanche terrain do not enter the backcountry this weekend, if you can, stick to simple terrain that is not threatened by overhead avalanche hazard. Avalanche danger will be on the rise throughout the stormy day, be sure you have a safe exit planned.
Summary
Confidence
Weather Forecast
FRIDAY NIGHT: Freezing level at valley bottom, moderate to strong west/southwest wind, 5 to 15 cm of light density snow expected.
SATURDAY: Overcast, freezing level beginning at valley bottom rising to about 800 m, strong west/southwest wind, 4 to 8 cm of snow expected during the day with another 5 to 10 cm Saturday night.
SUNDAY: Overcast, freezing level beginning around 1000 m, rising to 1800 m early in the day, strong southwest wind, 2 to 8 cm of snow at upper elevations with rain in the valleys. 10 to 15 cm of snow is expected at upper elevations Sunday night.
MONDAY: Scattered cloud cover, freezing level beginning around 1500 m and holding there throughout the day, strong west wind, 1 to 5 cm of snow at upper elevations with light rain in the valleys.
Avalanche Summary
New snow is beginning to stack up and plenty more is on the way which may lead to a natural avalanche cycle as we progress through the weekend.
This surprisingly large human triggered avalanche from near Wells Wednesday is a great example of the strange conditions that are created by reverse wind loading. Huge thanks to the reporting party for sharing this with the community.
Snowpack Summary
Southwest flow has started pushing some more serious precipitation our way. As of Friday afternoon the first wave of the storm has produced 3 to 7 cm around Barkerville and up to 30 cm around Blue River. There is now 15 to 45 cm of snow resting on an untested potpurri of weak layers including surgary facets, feathery surface hoar, and wind-affected snow that formed as a result of the cold, dry and windy drought period.
We've now got 40 to 80 cm of snow above the early February persistent weak layer which is composed of surface hoar. This layer is most prevalent at treeline and in "treeline-like" features like cutblocks. On steep south-facing terrain, this layer may consist of facets on a sun crust.
Terrain and Travel
- Watch for changing conditions today, storm slabs may become increasingly reactive.
- Storm slab size and sensitivity to triggering will likely increase through the day.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Problems
Storm Slabs
20 to 40 cm of recent snow rests on an untested mix of nasty weak layers which include surface hoar, facets, crust and firm old wind slabs. Storm slabs in wind exposed terrain may be quite sensitive to human triggering. This problem is expected to get worse as we move through the weekend.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A persistent weak layer buried 40 to 80 cm deep has produced recent large avalanches and is expected to become increasingly reactive this weekend. This layer has been most sensitive around treeline, but may also extend into alpine terrain and/or down into the trees.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 20th, 2021 4:00PM
