Avalanche Forecast
Issued: Mar 17th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Loose Wet.
mconlan,
Avalanche Canada
Wind slabs may still be found and the snowpack will weaken during the heat of the day, particularly on sun-exposed slopes. This warming is capable of triggering large avalanches.
Summary
Confidence
Weather Forecast
TUESDAY NIGHT: Cloudy with isolated flurries, moderate east wind, alpine temperature -11 C.
WEDNESDAY: Clear skies, light to moderate west wind, alpine temperature -4 C, freezing level 1600 m.
THURSDAY: Cloudy, light northeast wind, alpine temperature -10 C, freezing level 900 m.
FRIDAY: Clear skies, light to moderate northwest wind, alpine temperature -4 C, freezing level 1500 m.
Avalanche Summary
A large avalanche was remotely triggered on Monday near Fernie, as described in this MIN. The avalanche released on the faceted grains above the melt-freeze crust described in the Snowpack Summary. Otherwise, wet loose avalanche activity was noted on steep, sun-exposed slopes. Some wet loose activity also was observed on Tuesday.
Looking ahead, it is uncertain whether more persistent slab avalanche activity could arise during this period of generally sunny skies and modest air temperature. We will continue to track avalanche activity to observe for trends.
Snowpack Summary
Sunny skies have formed a melt-freeze crust on sun-exposed slopes. Recent strong easterly wind has produced wind slabs on lee terrain features. This wind direction is atypical, so you may find wind slabs in terrain features that don't usually have them.
A layer of faceted grains overly a melt-freeze crust from early February. This layer currently sits 30 to 60 cm below the surface. This layer has been the culprit of recent avalanche activity near Fernie.
The middle of the snowpack is generally strong, but the base of the snowpack may contain a weak layer of faceted grains that are most prominent in shallow rocky start zones with a snowpack depth of 150 cm or less.
Terrain and Travel
- Carefully evaluate steep lines for wind slabs.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Problems
Wind Slabs
Wind slabs formed during a reverse loading pattern from strong easterly wind. The most suspect terrain features are steep slopes near ridges. Should a wind slab be triggered, there is a potential that it could step down to a weak layer of faceted grains above a melt-freeze crust buried 30 to 60 cm.
Aspects: East, South East, South, South West, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Modest air temperature and sunny skies combine to weaken the snow surface. As this occurs, loose wet avalanche activity may result. The highest likelihood of this occurring is during the heat of the day on sun-exposed slopes. Note that the same warming trend also weakens cornices, so best to stay well back from them on ridges and avoid travelling beneath them.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 18th, 2020 5:00PM
