Avalanche Forecast
Regions: Field, Little Yoho.
While freezing levels remain elevated and winds values continue to transport snow at upper elevations, the forecast team is uncertain on how the deeper instabilities will react to these changes.
Confidence
Moderate
Avalanche Summary
No new avalanches observed or reported in the Little Yoho region.
Snowpack Summary
Moderate to strong SW winds have created windslab at upper elevations. In protected areas, 10-20 cm of loose snow sits over a denser mid-pack which has formed a slab over the weak facet layers below - this snow will create new wind slabs in lee areas. The December 17 weak layer is down 25-60 cm and becoming much less reactive in tests. The November 16 deep persistent layer of facets and depth hoar is near the base of the snowpack, continuing to show sudden failures. Profile from Ogden Bench on Wednesday.
Weather Summary
Warm temperatures will continue Saturday with freezing levels near 1600m. 0 to 5cm of new snow is expected in the Little Yoho region by mid-day Saturday. Ridgetop winds will begin to weaken Friday evening. More unsettled weather is forecasted for Sunday and the start of the week.
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices at this time.
Avalanche Problems
Wind Slabs
On Friday, wind values ranged from Moderate to Strong at upper elevations with some areas gusting to extreme. With increased winds and up to 20cm of loose snow available for transport, we expect isolated windslab development in the alpine.
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood: Possible - Likely
Expected Size: 1 - 1.5
Persistent Slabs
The December 17 facets that formed during the prolonged deep freeze in early December are down 30-60 cm. Although the layer is gaining strength, it is still worth monitoring this layer in the deeper snowpack areas (west) where it is still reactive in the mid-pack.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1.5 - 2.5
Deep Persistent Slabs
The lower snowpack is comprised of weak facets, with a slab formed over this weakness at treeline and in the alpine. This weak basal layer is uniform across most of the region and has the potential for human triggering. With the warmer weather in the forecast, we are including this problem below treeline.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1.5 - 3