Avalanche Forecast
Issued: Mar 1st, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
swerner,
Avalanche Canada
Strong southwest wind will howl on Tuesday building fresh wind slabs on northeast slopes. Forecast snowfall amounts vary across the region. If you see more than 25 cm in your riding area bump the avalanche danger up to HIGH and expect to see storm slabs on all aspects.
Summary
Confidence
Low - Forecast snowfall amounts are uncertain.
Weather Forecast
Monday Night: Snow 10-20 cm amounts vary across the region. Ridgetop wind strong from the southwest and alpine temperatures near -10. Freezing levels valley bottom.
Tuesday: Snow 5-10 cm with some sunny periods. Ridgetop wind strong from the South and alpine temperatures near -6. Freezing levels 900 m.Â
Wednesday: Snow 5-10 cm. Ridgetop wind mostly light but gusty from the southwest. Alpine temperatures near -4 and freezing levels 900 m.
Thursday: Cloudy with some flurries. Ridgetop wind strong from the southwest. Alpine temperatures near -1 and freezing levels 1100 m.Â
Avalanche Summary
No new reports on Monday.
On Sunday, a few natural wind slab avalanches were reported up to size 2 at treeline and in the alpine on northeast and northwest aspects. Wind slabs were also easily triggered on leeward slopes by the weight of a skier. Numerous loose wet avalanches were observed from steep terrain features.Â
On Saturday, we received some fantastic MIN reports showing significant wind effect and wind loading at upper elevations. Natural avalanches were reported as well as a skier-triggered slab size 1.5.Â
Thank you for the MIN reports!!
Reactive wind and storm slabs are the primary concerns for the forecast period. Loose-dry sluffing will likely be seen from steep terrain features.Â
Snowpack Summary
Up to 25 cm of recent snow fell by Monday morning. Fresh winds slabs may be reactive on leeward slopes, while touchy storm slabs may be found in isolated wind-sheltered locations. This brings 50 to 80 cm of snow on a variety of old snow surfaces consisting of hard wind-affected snow in exposed terrain and weak, faceted snow or surface hoar crystals in sheltered terrain. It may take some time for the snow to bond to these old surfaces.
Basal faceted snow remains part of the snowpack structure in much of the region. Once we see a substantial warm-up, we'll be thinking about the potential for the reactivation of basal layers.
Terrain and Travel
- Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
- Stick to simple terrain features and be certain your location isn't threatened by overhead hazard.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Wind Slabs
Cranking southwest wind and new snow have formed fresh new wind slabs. Reactive storm slabs may be found in wind-sheltered terrain.
Large looming cornices exist. Be diligent and give them a wide berth from above and below.
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
There is anywhere from 40 to 80 cm of snow above a mixed bag of old snow surfaces including hard wind pressed snow, sugary facetted snow, feathery surface hoar in sheltered locations that were buried in mid-February. A lot of uncertainty surrounds this possible interface and in places where it exists, it may reach threshold with more snow in the forecast. The main concern being wind or storm slab avalanches possibly stepping down to this layer and skier or rider triggering which would result in a consequential avalanche.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 2nd, 2021 4:00PM
