Avalanche Forecast
Issued: Feb 6th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
cgarritty,
Avalanche Canada
Initial assessment is the mindset to run with on Tuesday. Make observations about new snow amounts, reactivity, and wind slab distribution as you travel. Keep choosing terrain with the possibility of very large persistent slab avalanches in mind. This isn't the day to rule them out.
Summary
Confidence
Moderate
Avalanche Summary
We don't yet have observations from Monday's storm but it's expected that heavy snowfall and high winds sustained a natural storm slab cycle will take place throughout the region.
In the north of the forecast region, recent explosive control produced storm and wind slab avalanches up to size 2.5. This is a small sample of the avalanches that have been running through the recent stormy period and an indication of human triggering potential that may linger through the near term.
Large avalanches on more deeply buried persistent weak layers are continuing to be reported.
Snowpack Summary
A switch to lighter snowfall on Tuesday will see 5-10 cm adding to an impressive (and approximate)100-140 cm of storm snow from the past week. The new snow will add to heavily wind-affected surfaces and wind slabs as storm snow collectively settles over a layer of facets, crust, and previous wind-affected surfaces in alpine terrain. At treeline, our latest 30-40 cm overlies a widespread, supportive melt-freeze crust found up to 1800m and at all elevations on steep solar slopes.
The previous storm snow is not bonding well to the underlying surfaces.
The mid and lower snowpack continues to bond and stabilize while a number of buried weak layers remain a concern, having produced a few large avalanches recently.
Weather Summary
Monday night
Clearing with isolated flurries. Winds easing to light southwest.
Tuesday
Mostly cloudy with flurries bringing 5 to 10 cm of new snow, mainly in the far south of the region. Light southeast winds. Treeline high temperatures around -5.
Wednesday
Mostly cloudy with flurries bringing up to 5 cm of new snow. Light to moderate southwest winds shifting southeast. Treeline high temperatures around -4.
Thursday
Cloudy with increasing snowfall bringing 15-25 cm of new snow. Strong south winds. Treeline high temperatures around -1.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Make observations and assess conditions continually as you travel.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Storm Slabs
Recent heavy snowfall has perpetuated a natural avalanche cycle involving large storm slabs and wind slabs. A quick trend away from widespread storm slabs and toward a more terrain-specific wind slab problem is possible, but far from a certainty for Tuesday.
The largest and most reactive slabs will be found on north and east aspects at treeline and above.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A deeply buried weak layer still presents a Low Probability/High Consequence situation. New snow and wind has been testing this weakness in the snowpack and the results still aren't in. This layer would be most likely to be triggered in places where the snowpack is shallow and rocky.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 7th, 2023 4:00PM
