Avalanche Forecast
Issued: Mar 18th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
cgarritty,
Avalanche Canada
Persistent slabs remain a concern at lower elevations. Observations will decrease as folks retreat to low-risk activities and social distancing. Be sure to keep risk tolerance to a minimum if you're heading out and to share your observations on the Mountain Information Network.
Summary
Confidence
Weather Forecast
Wednesday night: Clear. Light east or northeast winds.
Thursday: Sunny. Light east or northeast winds. Alpine high temperatures around -8.
Friday: Sunny. Moderate west winds. Alpine high temperatures around -4.
Saturday: A mix of sun and cloud. Light north winds. Alpine high temperatures around -10.
Avalanche Summary
No new avalanches were reported over the past couple of days, however a natural wind slab avalanche cycle up to size 2.5 (large) was observed on Saturday. One size 3 (very large) was reported on a south aspect as well. No avalanches were reported at lower elevations where surface hoar is known to exist but where observations are scarce.
Looking forward, the possibility for human triggering of isolated wind slabs at upper elevations is now likely limited to very steep terrain at ridgecrest. At lower elevations, human triggering of avalanches remains possible where slabs have formed over persistent weak surface hoar layers.
Snowpack Summary
Recent sunshine has been strong enough to create a new surface crust on steep southerly slopes, thickest at lower elevations. Recent wind slabs are expected to be on a positive stabilizing trend.
At lower elevations, two surface hoar layers 50-60 cm and 75-90 cm below the surface remain a concern - especially where a slab has formed on the surface from warming and/or winds over the weekend.
Terrain and Travel
- Be very cautious in open terrain features, such as cutblocks, gullies, and cutbanks.
- Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
Problems
Persistent Slabs
Previous storm snow has been settling into slabs over a persistent weak layer of surface hoar. Steep openings at lower elevations are the most likely areas to find and trigger this layer. While size is not expected to be large, be wary of terrain traps like tree wells or creeks and ravines where debris piles up deeply even from small slides.
Aspects: All aspects.
Elevations: Below Treeline.
Likelihood
Expected Size
Wind Slabs
Aging wind slabs exist on south, southwest, and west aspects. More recent slabs in steeper leeward features at ridgecrest may still react to the weight of a person or machine.
Aspects: South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 19th, 2020 5:00PM
