Avalanche Forecast
Issued: Feb 10th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
dsaly,
Avalanche Canada
Pay attention to the wind, theres a lot of recent snow to build fresh wind slabs.
Summary
Confidence
Avalanche Summary
On Thursday the fresh snow was reactive to skiers, with sluffing, natural storm slab avalanches to size 2.5, and wind slabs to size 1.5 reactive to skiers. With more snow in the forecast, expect the snowpack to continue to be reactive to skier- and rider-traffic.
On Wednesday, skiers triggered a large, size 2 avalanche near Ningunsaw. The Deep Persistent avalanche was triggered on an east aspect near ridgetop in a thin, rocky start zone and failed on basal facets.
On Wednesday and Thursday morning, avalanche control operators reported natural and explosive-triggered wind and storm slab avalanches up to size 3, likely occurring with the recent heavy snowfall.
Evidence of a widespread natural avalanche cycle was observed throughout the region on Monday and Tuesday, with storm slabs and wind slabs observed to an impressive size 3 (very large). Many slabs started off dry but finished running as wet loose slides at the bottom of their runouts.
Snowpack Summary
40-70 cm recent storm snow covered older wind-affected surfaces and a supportive melt-freeze crust up to 1800 m and steep solar slopes. South-southwesterly winds have been creating wind-affected surfaces and wind slabs of varying age and reactivity on an ongoing basis.
Recent and forecast storm snow will form only the uppermost portion of 100-150 cm of February storm snow settling over a layer of facets, crust, and previous wind-affected surfaces in alpine terrain. We're continuing to track this layer given recent avalanches on this interface under the patterns of continuous loading and successive natural avalanche cycles.
The mid and lower snowpack continues to bond and stabilize while a number of buried weak layers are still being tracked by professionals in the region, having produced a few large avalanches in the not-too-distant past.
Weather Summary
Friday night
Light flurries, 5 cm overnight. Southwest winds increasing to 30-40 km/hr. Treeline low temperature -9 C with freezing level dropping to valley bottom.
Saturday
Mostly cloudy with isolated flurries, 5-10 cm. Southwest winds gusting 50-70 km/hr. Treeline high temperature -5 C.
SundayHeavy snow starting late Saturday, 15-30 cm by Sunday afternoon. Southwest wind gusting to 80 km/hr with the storm. Treeline high temperature -2 C. Freezing level rising above 1000 m.
MondaySnow tapering early morning, 25-50 cm storm totals forecast. Southwest winds 40-60 km/hr. Treeline high temperature -5 C./hr. Treeline high temperature -2 C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Don't let the desire for deep powder pull you into high consequence terrain.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
Problems
Wind Slabs
The increasingly strong southwest wind overnight will build reactive slabs for Saturday morning. Along with flurries through the day and another round of precipitation forecast to start late Saturday, expect new snow to continue to be reactive to rider traffic, especially when accumulation happens rapidly (over 20 mm/24 hrs) or in areas impacted by wind.
Aspects: All aspects.
Elevations: Alpine, Treeline.
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 11th, 2023 4:00PM
