Avalanche Forecast
Issued: Feb 20th, 2021 4:30PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Storm Slabs.
Tim Haggarty,
A significant storm will arrive Sunday. Expect conditions to change during the day. By Monday, a significant step back in terrain choice will be warranted.
Summary
Weather Forecast
Continued light snowfall overnight Saturday. Sunday, trace amounts of snow, up to 10 cm, favouring the North part of the region will fall, as a warm front arrives late in the day. Freezing levels will approach 1800m and alpine winds will reach 70-80km/h. A cold front Monday will bring 10-15cm of snow, peak winds and cooling as it sweeps N to S.
Snowpack Summary
Extensive wind effect with a few thin wind-slabs and fresh cornice growth developing in the alpine. At treeline and below the snowpack is well settled except the surface snow which is facetted and sluffs in steep terrain although wind effect is starting to creep down. A facet and sun crust layer buried Jan 27 persists at treeline down 30-40 cm.
Avalanche Summary
Moderate wind transport at ridge top led to a least one small cornice triggered avalanche in Kootenay NP today. Sunshine Village reported working with fresh cornice growth and small fresh wind slabs at ridge crests and into isolated treeline areas. Thursday, Sunshine triggered a very large cornice that initiated a size 2.5 persistent slab.
Confidence
Intensity of incoming weather systems is uncertain on Sunday
Problems
Wind Slabs
Winds will be strong out of the west overnight Saturday and reach Extreme as the storm arrives Sunday. Expect the small wind-slabs in the alpine to develop further and extend to treeline elevations especially as fresh snow and warming temps are added
- Pay attention to overhead hazards like cornices which could trigger slabs.
- Use caution in lee areas. Recent wind loading has created wind slabs.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Storm Slabs
New snow, intense winds and warm temperatures associated with the storm arriving late Sunday will promote slab development at all elevations as snowfall continues through Tuesday. Expect the new slabs to be touchy over the current faceted surfaces.
- The new snow will require several days to settle and stabilize.
- Use conservative route selection, choose moderate angled and supported terrain with low consequence.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 21st, 2021 4:00PM
