Avalanche Forecast
Issued: Apr 7th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Cornices.
swerner,
Avalanche Canada
Fresh snow amounts are variable across the region, and may have formed reactive wind slabs on many aspects due to changing wind directions. Keep in mind that even brief periods of sun could initiate avalanche activity in the new snow.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain. Uncertainty is due to the extreme variability of wind effect on the snowpack.
Weather Forecast
Wednesday Night: Cloudy with snow 5-10 cm. Ridgetop wind moderate from the northwest. Alpine temperatures near -13 and freezing levels valley bottom.
Thursday: Mostly cloudy with some sunny periods and isolated flurries. Ridgetop wind moderate to strong from the west-northwest. Alpine temperatures near -10 and freezing levels 1000 m.
Friday: Snow 10 cm. Ridgetop wind strong from the southwest. Alpine temperatures near -10 and freezing levels 1000 m.
Saturday: Mix of sun and cloud. Light to moderate northwest wind and freezing levels 1300 m.
Avalanche Summary
New snow and strong winds shifting from the southwest to northwest may have formed fresh and reactive wind slabs on leeward slopes at treeline and in the alpine.Â
Loose surface avalanches within the new snow can be expected from steeper slopes and terrain features, especially if the sun comes out.
Give cornices a wide berth from above and below, especially when the sun is out.
Snowpack Summary
Winter weather returns with new snow 10-20 cm across the region. Shifting wind directions from the southwest to the northwest could form new wind slabs on leeward slopes and behind terrain features. The new snow sits on a series of melt-freeze crusts on all aspects below 1900 m and southerly aspects to mountain top. On North aspects in the alpine, the new snow will sit on dry wintery and wind-affected snow surfaces.Â
The recent warm weather is expected to have helped old persistent weak layers heal, including a few crusts buried over the last month as well as a facet layer 150 cm deep from the mid-February cold snap.
Terrain and Travel
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Use ridges or ribs to avoid areas of wind loaded snow.
- Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Wind Slabs
New snow and strong southwest to northwest wind may form fresh wind slabs. They will most likely be isolated to immediate lees of ridgecrests and roll-overs at upper elevations.
Loose snow avalanches within the new snow may occur from steeper slopes and terrain features, especially in places that receieved heavier amounts of new snow, and if the sun comes out.
Aspects: North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Cornices are especially fragile this time of year, especially when the sun is out. Cornice falls are dangerous on their own and they can also trigger slabs on slopes below.
Aspects: North East, East, South East.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 8th, 2021 4:00PM
