Avalanche Forecast
Issued: Feb 19th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Persistent Slabs and Deep Persistent Slabs.
AB,
Avalanche Canada
Snowfall and wind for the next 48 hours will hold the danger rating at HIGH in the alpine. The deep slab problem could finally have enough load with the incoming snow to start producing avalanches that run full path.
Summary
Confidence
Avalanche Summary
No significant avalanches were observed or reported on Sunday. However, numerous avalanches up to size 3 were reported in the past 5 days, previous to the recent storm snow and wind. With the recent weather inputs, forecasters expect there to be a substantial cycle Mon and Tues.
Snowpack Summary
15 to 35 cm of storm snow over the past 72hrs with moderate to strong SW-W winds have created extensive wind effect in the alpine and contributed to wind slab development. Several persistent weak layers exist 35-65cm below the surface. These weak layers include crusts, facets and surface hoar buried in January and are producing sudden test results in some locations. Deeper in the snowpack, the November crust/facet layer is found about 40 cm above the ground and also continues to produce sudden test results.
Weather Summary
Snowfall up to 20cm is expected Monday late afternoon and into the next day. The wind will remain elevated in the 60-80km/hr range from the West until late in the day Monday. After the regime of wind and snow temps will dive as an arctic air mass settles midday Tuesday.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Make conservative terrain choices and avoid overhead hazard.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Cornice failure may trigger large avalanches.
Problems
Wind Slabs
Up to 30cm of recent storm snow with consistent strong Westerly wind continues to build slabs. Use caution in all lee areas with wind effect. These avalanches have the potential to start small, but then step down to the deeper weak layers.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Slabs 30-60 cm deep overly three persistent weak layers formed in January which are a mix of crusts (solar aspect), facets (cold aspects) and isolated surface hoar. We have primarily seen avalanches failing on crusts on solar aspects but examples have been seen on other aspects as well.
Aspects: South East, South, South West, West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Facets and depth hoar at the bottom of the snowpack provide weak support for the entire snowpack. Incremental snowfall since the start of February has brought the overlying slab to the tipping point and we have starting to see signs that the weak base is becoming overloaded. The snowfall and wind expected through Tuesday are likely to cause large, destructive avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 20th, 2023 4:00PM
