Make a plan to retreat from avalanche terrain as the storm intensifies, and stick to it! Heavy snowfall, strong wind, and rising temperatures are expected to begin a natural avalanche cycle.
Steady snowfall will form slabs that are increasingly widespread, reactive, and consequential over the day. Expect the greatest danger where wind loading is occurring.
The rain line will climb over the day. Steep slopes at elevations receiving wet snowfall or especially rain on previously dry snow will become increasingly unstable.
Only a few small skier-triggered wind slabs were observed near the Highway 16 corridor on Saturday. On Friday, a few natural wind slabs occurred in the alpine on south and east aspects. They were large (size 2 to 2.5).
On Thursday, soft wind slabs developing in the alpine produced releases to size 1.5 with sled traffic, to size 1 with skier traffic, and ran naturally to size 2 in the southeast of the region.
A more widespread storm slab problem should develop on Monday.
30 to 40 cm of new snow should accumulate by end-of-day Monday, adding to about 50 cm since March 7, which has been redistributed by strong winds in exposed alpine and treeline terrain. It all sits on old wind effect at these elevations and on a melt-freeze crust to at least 1600 m and it may contain two crusts on treeline solar aspects.
Layers from late Jan and early Feb, both made of surface hoar, facets, and/or crust, are 100 to 150 cm deep. They're showing up less in test results but may remain a problem in isolated thin-to-thick snowpack areas above the elevation of the latest crust. A north aspect at 1600 m in the lower Canoe gave moderate, propagating results on the 90 cm-deep Jan layer Wednesday.
Sunday Night
Cloudy with increasing flurries bringing about 10 cm of new snow. 40 to 60 km/h southwest ridgetop wind, increasing. Treeline temperature rising to -7 °C.
Monday
Cloudy with continuing snowfall bringing 20 to 30 cm of new snow. 60 to 70 km/h southwest ridgetop wind. Treeline temperature reaching -3 °C.
Tuesday
Cloudy with increasingly wet snowfall bringing 15 to 30 cm of new snow to higher alpine, including overnight, rain below about 2200 m. 60 to 80 km/h southwest ridgetop wind, easing a bit. Treeline temperature 2 °C with freezing level to 2500 m by end of day.
Wednesday
Cloudy with continuing wet flurries bringing up to about 10 cm of new snow above 2000 m, rain below. 60 km/h southwest ridgetop wind. Treeline temperature 2 °C with freezing level falling to 2100 m.
More details can be found in the Mountain Weather Forecast.
