Avalanche Forecast
Issued: Jan 18th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
Ian Jackson,
Avalanche control results in Yoho today showed that conditions are ripe for triggering in steep alpine and treeline wind affected terrain.
Summary
Weather Forecast
Wednesday looks to be cold (lows of -20 to -25 at treeline) and clear with moderate NW alpine winds gradually increasing to strong by the evening. On Thursday, a small system is forecast to bring 5-10 cms of snow with strong W alpine winds and freezing levels staying below 1000m. Friday looks to be overcast with moderate NW winds and light snow.
Snowpack Summary
10-15 cms of low density snow with little wind effect sits on top of windslabs in the alpine and in some treeline areas. These overlie facets in many places, producing moderate to hard test results. The Dec. 2 crust and facets are generally 60-90cm deep in the snowpack. Some thin snowpack areas have lingering basal depth hoar and facets.
Avalanche Summary
Observations from a flight showed evidence of a small avalanche cycle to size 2 that had occurred overnight. Avalanche control in Yoho today produced slabs with every shot. Most were failing on a windslab or facet layer 40-60cm deep and then entraining facets in the track. One stepped down to the November facets ~ 180 cm deep.
Confidence
Due to the number of field observations
Problems
Wind Slabs
10-25 cms yesterday added to the previous windslabs in alpine and treeline terrain. In some areas, these have been enough to initiate deeper layers in the snowpack once triggered.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Minimize overhead exposure during periods of heavy loading from new snow, wind.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
This problem represents both the Dec. 2nd crust/ facet layer (treeline and below) and layers of faceted snow that were formed during the late December cold snap (all elevations). If triggered, either layer will result in large avalanches.
- Forecasters are operating with alot of uncertainty at this time.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 19th, 2022 4:00PM
