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RegisterMar 9th, 2021–Mar 10th, 2021
North Columbia.
Lingering wind slabs may remain reactive to human triggers in the alpine. Steep, rocky, cross loaded features below alpine ridgetops are some of the most likely places to trigger wind slabs.
TUESDAY NIGHT: Cloudy with isolated flurries; 0-3 cm. / Moderate, southwest ridgetop wind / alpine low temperature -10 / Freezing level valley bottom.
WEDNESDAY: Cloudy with flurries; 2-5 cm. / Light, southwest ridgetop wind / alpine high temperature -6 / Freezing level 700 m.
THURSDAY: Sunny / Light, northwest ridgetop wind / alpine high temperature -4 / Freezing level 1200 m.
FRIDAY: Mix of sun and cloud / Moderate, west ridgetop wind / alpine high temperature -2 / Freezing level 1500 m.
On Monday, evidence of a previous small cornice failure triggering a size 2.5 windslab on a north aspect in the alpine was reported. Additionally, several naturally triggered wet loose avalanches up to size 1.5 were reported on steep, rocky, sun exposed slopes.
On Saturday, at least three large to very large (size 2.5 to 3) wet slab avalanches were observed at low elevation (1100-1400 m) on south aspect slopes, triggered in response to warm temperatures and strong sun.
Up to 25 cm dry soft snow can be found on shaded aspects above around 1500 m. On south-facing slopes and at lower elevations expect crusty snow in the morning and soft moist snow in the afternoon. Winds have slackened off of late, but recent wind slabs and cornices still pose a hazard close to steep ridgelines.
The lower snowpack has strengthened over the past week as previous persistent weak layers have become unreactive. The main layers that we had been tracking were a layer of facets that was buried in mid-February (60-100 cm deep) and a layer of surface hoar and/or a crust that was buried in late January (80-120 cm deep).