Avalanche Forecast
Regions: Little Yoho.
New snow combined with some intense winds and mild temperatures have formed new surface slabs. With the Dec 18 Persistent Weak Layer still a concern in this area be conservative and manage your exposure carefully. TH
Weather Forecast
The remains of Sunday's storm should play out early Monday morning and bring another 5 to 10 cm as temperatures start to cool. Winds should also diminish around midnight but will likely remain in the moderate range at the treeline level. Expect a light snowfal (5 to 10cm) Monday with continued cooling into Tuesday before we may see some clearing.
Snowpack Summary
New windslabs are being formed in open lee areas treeline and above. The Dec 18 surface hoar layer is down 40-50 cm. This layer is very prominent and is producing moderate test results and lots of whumphing. With up to 20cm of new snow in the last 72 hrs and another 5 to 10 expected Sunday and Monday morning, this layer may become active again.
Avalanche Summary
Skiers were able to easily trigger the sensitive new windslabs that have formed at Treeline and above today in neighboring areas. These soft slabs propagated up to 20m and were up to 40cm deep. Poor visibility made it difficult to see further evidence of avalanche activity.
Confidence
Intensity of incoming weather systems is uncertain on Sunday
Avalanche Problems
Wind Slabs
New windslabs 15 to 50 cm deep can be found in almost any lee areas including cross loaded features. These slabs will continue to build Sunday night and Monday with continued precipitation and winds.
- If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.
- Be cautious as you transition into wind affected terrain.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood: Very Likely
Expected Size: 1 - 3
Persistent Slabs
A persistent weak layer from Dec 18th of surface hoar/crust/facets lurks 50-60 cm's below the surface. This layer is most reactive at the tree line elevation where it is a surface hoar/crust combination.
- Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.
- Choose conservative lines and watch for clues of instability.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2 - 3
Storm Slabs
15 to 25 cm now lies over the Jan 16 interface that consists of Surface Hoar, Facets, Suncrusts, and windslabs. Mild temperatures will encourage the formation of a soft slab over this weak layer.
- Minimize exposure during periods of heavy loading from new snow, wind.
- The new snow will require several days to settle and stabilize.
Aspects: North, North East, East, South East, South.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 2