Avalanche Forecast
Issued: Jan 20th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Wind Slabs.
TH,
Avalanche Canada
The snowpack remains generally shallow and weak with a few deeper areas found to the west of the region.
Although the upper snowpack may be starting to "feel" more supportive, bear in mind that what you are feeling are effectively surface slabs that overlie weak, very unsupportive, faceted snow. This structure is not to be trusted.
Stick to low consequence terrain.
Summary
Confidence
Moderate
Avalanche Summary
No new natural activity observed today. The Lake Louise avalanche control team triggered another deep persistent slab on a S aspect at treeline with explosives yesterday (sz 1.5). They also found fresh windslabs this morning in immediate lees. These were generally 10-15cm, but up to 30cm deep, and propagated fairly well : up to 60m wide.
Snowpack Summary
Dribs and drabs of snow over the past 2 weeks have amounted to 10cm. This sits on a surface hoar /crust layer which is sporadic in the region. The Dec 17 surface hoar/sun crust layer is down 25-50cm, and generally not reactive. The Nov. 16 deep persistent layer is down 40-90cm and continues to produce sudden failures in snowpack tests. In Little Yoho, these two layers are deeper and more spread apart in the snowpack.
Weather Summary
West to NW winds Friday evening with alpine Temperatures -10 to -15C. Saturday an upper trough moves through the region bringing light accumulations of snow north of Lake Louise with west winds and freezing levels near valley bottom. Saturday night a cold front will pass bringing 5cm , northwest winds and alpine temperatures near -10C. Ridgetop winds will remain 20-40km/hr for the period.
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Deep Persistent Slabs
The lower snowpack is comprised of weak facets and depth hoar with the upper snowpack forming a 40 to 90cm thick slab above. This weak basal layer is uniform across most of the forecast region and has been responsible for most of the avalanche activity to date this season.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Fresh new slabs from moderate winds overnight Thursday are found in isolated immediate lees. Winds are forecast to reach these speeds again Saturday and are likley to arrive with at least some new snow which should work to build this problem further.
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Jan 21st, 2023 4:00PM
