Several weak layers in the snowpack have resulted in very large and widespread avalanches over the long weekend.
It's a good time to stick to conservative terrain.
Two persistent weak layers of surface hoar/ facets/ crust from Feb 7th and Jan 26th are buried in the upper meter of the snowpack and remain a significant concern. These layers continue to show reacivity at all elevations.
Up to 15 cm of new snow is in the forecast, adding more load to recently built storm slabs. These slabs will be most reactive on lee slopes below ridgetops or where they are overlying surface hoar.
A natural avalanche cycle was observed on Saturday up to size 3. Numerous skier-triggered and remote-triggered slabs also occurred over the weekend, up to size 2. Explosive control triggered several size 3 slabs on Sunday.
Many of these avalanches failed on persistent weak layers. Several occurred at lower elevations below treeline on relatively benign slopes.
Recent MIN reports in the region also highlight the reactivity of these weak layers. See photos below.
Around 5 to 15 cm is in the forecast for overnight and through Tuesday.
There is a lot of variability in the region, but three prevalent surface hoar layers stand out:
Currently, 20 to 80 cm of storm snow is covering a layer of surface hoar or sun crust buried on Feb 13th.
Below that, another 20 to 40 cm of older snow is covering a second layer of surface hoar or a crust from Feb 7th.
Lastly, the late January layer of surface hoar/facets/crust is buried 60 to 100+ cm from the surface.
All of these layers have been reactive in the region recently.
The remaining snowpack has no layers of concern
Monday Night
Mostly cloudy. 1 to 5 cm of snow. 20 km/h south ridgetop wind. Treeline temperature -7 °C.
Tuesday
Mostly cloudy. 5 to 15 cm of snow. 10 km/h southwest ridgetop wind. Treeline temperature -8 °C.
Wednesday
Mix of sun and clouds. 0 to 5 cm of snow. 10 km/h southwest ridgetop wind. Treeline temperature -12 °C.
Thursday
Mix of sun and clouds. 0 to 2 cm of snow. 10 km/h west ridgetop wind. Treeline temperature -14 °C.
More details can be found in the Mountain Weather Forecast.
