We should finally be on the home stretch with our persistent slab problems. A few more days of restraint and discipline before the next warm-up gets the Columbias to shed some layers.
Multiple weak layers present roughly 1 - 2 m deep are adjusting to a new snow load and continue to produce surprising avalanches. Avalanches failing on these layers have been large and destructive.
Recent snow settling on mid-storm interfaces and a deeper crust may still be triggerable on steep slopes. Local operators have also found wind slab formation well into below treeline on all aspects as a result of strong winds this week.
A week of uncertainty about lingering persistent slabs after the warmup, with enough activity to keep our guard up.
Among more predictable storm/wind slab activity Thursday, we had a size 2 on the Jan layer in Meadow Creek, unknown trigger, three natural size 2s southeast of Revy, and explosives controlled persistent slabs to size 4 in the Purcells (size 2 in the Adamants)
Wednesday we saw size 2 persistent slabs on unsupported features around 1800 m just west of Revelstoke.
Storm snow snow since March 7 totals 60 - 100 cm around Revelstoke and 30 to 50 cm farther south. It has been redistributed by southwest winds in exposed higher elevation terrain and sits on old wind-affected surfaces at treeline and above or on a crust, which extends up to 1900 m near Highway 1--closer to 2200 m in the south.
Three problem layers of surface hoar, facets and/or crust formed in January and February exist in the mid-snowpack, 1-2 m deep. They produced numerous destructive avalanches during the weekend warmup and sporadic releases in the days since, making them difficult to rule out, even as factors like a bridging crust at lower elevations have reduced their likelihood of triggering.
Friday Night
Partly cloudy with scattered flurries bringing a trace of new snow except for a band south of Revelstoke that may see 5 to 10 cm into the early morning. 20 km/h west ridgetop wind. Treeline temperature -10 °C.
Saturday
A mix of sun and cloud after flurries diminishing. 30 km/h northwest ridgetop wind. Treeline temperature -11 °C.
Sunday
A mix of sun and cloud with cloud increasing and afternoon flurries starting with a trace of new snow. 15 to 40 km/h west ridgetop wind, increasing. Treeline temperature -9 °C.
Monday
Cloudy with snowfall continuing from overnight bringing 25 to 40 total cm of new snow. 50 km/h southwest ridgetop wind. Treeline temperature reaching 0 °C as freezing level jumps to 1900 m.
More details can be found in the Mountain Weather Forecast.
