Avalanche Forecast
Issued: Feb 27th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
zryan,
Avalanche Canada
Natural avalanche activity has tapered, but human-triggering remains LIKELY.
Storm slab reactivity is expected to persist for longer than in typical, due to the weak surface they are sitting on.
Summary
Confidence
Avalanche Summary
Last week, northerly outflow winds created small (size 1) but reactive wind slabs at ridge crests.
On Sunday, a widespread natural cycle occurred throughout the region. Reports came in of very touchy human-triggered storm slabs (size 1-2) averaging 30-60 cm deep and up to 100 cm deep in wind-loaded areas.
Looking forward to Tuesday, dangerous avalanche conditions will persist. Human-triggered storm slabs remain likely. Storm slab reactivity is expected to persist for longer than is typical due to the weak surface they are sitting on.
Check out last Friday's North Shore Snowpack Update for a picture of the unusual snowpack setup leading into last weekend's storm.
Snowpack Summary
An additional 10-15 cm of new snow will add to Saturday night's storm that brought 30-50 cm of new snow down to valley bottom. This new snow has bonded poorly to the underlying surface formed by recent wind and cold temperatures. This surface consists of weak faceted snow, old hard wind slabs and a breakable crust between 1100 and 1600 m.
The mid and lower snowpack is well-settled, strong, and consolidated.
Snowpack depths are reaching 250 cm at treeline.
Weather Summary
Monday night
Mainly cloudy with scattered flurries, 5 cm accumulation. Alpine temperatures drop to a low of -4 °C. Ridge wind south 10-20 km/h. Freezing level 300 meters.
Tuesday
Cloudy with flurries, 5-10 cm of accumulation Alpine temperatures reach a high of -4 °C. Light variable ridge wind. Freezing level 500 meters.
Wednesday
Cloudy with sunny periods and isolated flurries, up to 5 cm of accumulation. Alpine temperatures reach a high of -5 °C. Ridge wind southwest 15 km/h to 40 km/h. Freezing level 400 meters.
Thursday
Periods of snow, heavy at times, 10-30 cm of accumulation. Alpine temperatures reach a high of -2 °C. Ridge wind southwest 40 km/h gusting to 70 km/h. Freezing level 700 meters.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
- Closely monitor how the new snow is bonding to the crust.
- Keep your guard up at lower elevations. Storms slabs have been reactive at all elevations.
- Avoid terrain traps where the consequence of any avalanche could be serious.
- Don't let the desire for deep powder pull you into high consequence terrain.
Problems
Storm Slabs
An additional 5-15 cm will accumulate over Saturday night's 50 cm of storm snow. This new snow has bonded poorly to the underlying surface and created a widespread storm slab problem averaging 30-60 deep and up to 100 cm deep in wind-loaded areas.
Storm slab reactivity is expected to persist for longer than is typical, particularly in areas where slabs are sitting on a weak layer of facets and/or a crust.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 28th, 2023 4:00PM
