The tail end of a warm storm will bring dynamic conditions on Monday. Expect dangerous avalanche conditions at most elevations for most of the day.
At 60 to 100 cm deep, a weak layer of surface hoar is at prime depth for rider triggers to produce large avalanches. It can be most likely triggered on steep roll-overs in wind-sheltered terrain around treeline.
Fresh storm slabs are likely to be reactive on Monday, especially in wind-loaded leeward terrain features at upper elevations.
Overnight rain will leave lower elevations primed for loose wet avalanches on Monday morning. They will become less likely as temperatures cool and a crust forms.
Observations have been limited. As the storm clears Monday, we're expecting to see evidence of a natural cycle on the weekend; storm slabs at upper elevations, possibly persistent slabs around treeline, and loose wet avalanches at lower elevations.
If you are getting out in the backcountry, consider sharing your observations on the Mountain Information Network (MIN)!
20 to 40 cm of snow fell with strong wind this weekend. A surface crust will form over the day Monday at elevations where the storm ended with rain.
In wind-sheltered areas around treeline, a couple of weak layers of surface hoar are buried 60 to 100 cm deep. These were reactive in snowpack tests last week, but so far we haven't seen evidence of avalanche activity on them.
The mid snowpack contains a crust with small facets above it, but does not present a problem at this time.
The snowpack is around 150 cm deep at treeline, tapering quickly with elevation.
Sunday night
Partly cloudy. 10 to 20 mm of mixed precipitation. 70 km/h south ridgetop wind. Treeline high temperature +2 °C. Freezing level 1700 m.
Monday
Mostly cloudy. 5 cm of new snow. 50 km/h southwest ridgetop wind. Treeline temperature +2 °C in the morning then cooling to -3 °C. Freezing level 1800 m falling to valley bottom.
Tuesday
A mix of sun and cloud. 5 to 10 cm of snow. 50 km/h southwest ridgetop wind. Treeline temperature -3 °C.
Wednesday
A mix of sun and cloud. 10 cm of snow. 50 km/h southwest ridgetop wind. Treeline temperature -5 °C.
More details can be found in the Mountain Weather Forecast.
