Wind slabs will be the main concern on Monday. Be on the lookout for stiff, drifted snow and signs of instability like shooting cracks as you enter wind-affected terrain.
Small inputs of new snow will continue to feed wind slabs. As wind direction shifts southeast on Monday, watch for changes in loading patterns. Treat wind affected areas below treeline with caution.
40-60 cm of snow sits over a weak layer on a thick crust. Over the weekend, avalanches were reported to have run on this layer.
Sunday night: Up to 5 cm of new snow. Moderate southwest wind. Freezing level valley bottom.
Monday: 5-10 cm of new snow. Moderate to strong southeast wind. Treeline temperatures around -4 C. Freezing level 1000 m.
Tuesday: 5-10 cm of new snow overnight then clearing. Light southwest wind. Treeline temperatures around -7 C. Freezing level 500 m.
Wednesday: Scattered flurries. Light southeast wind. Treeline temperatures around -10 C. Freezing level 500 m.
Storm slabs size 1.5-2 were reactive to explosive and cornice loads on Sunday. This MIN report paints an excellent picture of touchy avalanche conditions and good decision making during the storm Saturday. Skier control work near Nelson produced storm slabs up to size 1.5 and explosive control work in Kootenay Pass produced storm slabs up to size 2.5. These avalanches were 30-50 cm deep, failing on the thick crust layer described in the snowpack summary.
10-25 cm of recent snow has seen redistribution by strong wind at upper elevations.
The defining feature of the snowpack is a prominent and widespread crust that now sits 40-60 cm below the surface. In many places, overlying snow is well-bonded to the crust but in others, including Kootenay Pass, weak faceted grains have been observed growing above it around treeline. Snowpack models show the faceting process progressing quickly at this elevation, likely due to the amount of heat and moisture trapped by the crust. We will be closely monitoring this layer going forward.
See these is well detailed in Kootenay pass from treeline at Kootenay Pass before the storm. This MIN gives a similarly detailed description of the thinner snowpack below treeline near Rossland. Snow depths are roughly 80-140 cm at treeline throughout the region.
An upside down upper snowpack has resulted from 10-25 cm of warm, wind affected snow falling over unconsolidated lower density snow sitting on a thick crust. This crust, now 40-70 cm deep, is well detailed in this MIN report from treeline at Kootenay Pass before the storm. This MIN gives a similarly detailed description of the thinner snowpack below treeline near Rossland. Snow depths are roughly 80-140 cm at treeline throughout the region.
