Avalanche Forecast
Issued: Feb 26th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
lbaker,
Avalanche Canada
Dial back your terrain choices if you are finding more than 20 cm of new snow. Use caution as you transition into wind affected areas.
The lower snowpack remains weak, small avalanches may easily step down to deeper layers. Keep a large margin of error by avoiding thin start zones and large slopes.
Summary
Confidence
Avalanche Summary
On Saturday, a small size 1.5 machine accidental persistent slab avalanche was reported from a shallow alpine feature that had previously been explosives controlled.
Explosive control on Thursday and Friday, produced slab avalanches to size 3, including one deep persistent slab avalanche. Evidence of a natural cycle to size 3 continues to be observed.
Deep persistent slab avalanches continue to be periodically reported throughout the region. Including a very large skier-triggered, fatal avalanche last Thursday. This MIN post from Thursday observed a size 3 avalanche near Golden over 1 m deep. Likely a naturally triggered slab, the exact failure plane is unknown. The continued activity indicates the weak and unpredictable snowpack remains concerning.
Snowpack Summary
10-15 cm of new low-density snow sits over 20-50 cm of wind affected storm snow.
A layer of surface hoar is now buried by 30 to 50 cm in sheltered terrain and a thin sun crust on steep south-facing terrain. In general, the mid snowpack is well consolidated and bonding.
The lower snowpack contains a number of buried weak layers such as surface hoar with variable distribution, as well as a widespread layer of large, weak basal facets and depth hoar in places. These weaknesses have been responsible for a number of recent very large, destructive avalanches and will continue to be a concern.
Weather Summary
Sunday Night
Cloudy with isolated flurries, 2 cm accumulation. Westerley ridgetop wind 10-25 km/h. Freezing levels drop to valley bottom. Alpine high of -10 °C.
Monday
Partly cloudy with isolated flurries, trace accumulation. Light southwesterly ridgetop wind. Alpine high of -9 °C. Freezing levels valley bottom.
Tuesday
Mainly cloudy with isolated flurries, 2 cm accumulation. Light variable ridgetop winds. Freezing levels valley bottom, alpine high of -9 °C.
Wednesday
Mix of sun and cloud. Light westerly ridgetop wind. Alpine high of -8 °C. Freezing levels 700 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Avoid rock outcroppings, convexities, and anywhere the snowpack is thin and/or variable.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Storm Slabs
Variable moderate winds and 10-15 cm of storm snow have built reactive storm slabs at higher elevations. Wind affected snow may sit over a layer of surface hoar in sheltered terrain features, or over a sun crust on south facing slopes which may increase reactivity.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
The base of the snowpack remains very weak. Very large human triggered avalanches are possible at higher elevations. Avoid shallow and rocky areas, where the snowpack varies rapidly from thick to thin.
The mid and lower snowpack also contain several surface hoar layers. Due to the overall weak snowpack structure, small avalanches are likely to step down to any of the deeper weak layers creating large and destructive avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 27th, 2023 4:00PM
