Sharpen your discipline and dial back your exposure to avalanche terrain during the warmup. Destructive persistent slab avalanches are expected to become increasingly likely to trigger.
Weak layers exist below the most recent storm snow and up to about 90 cm deep. They will be increasingly likely to produce avalanches with forecast warming. Small avalanches may also step down.
Solar warming will work to destabilize snow on sun-exposed slopes sheltered from wind. Wet snow may shed naturally or with a human trigger.
A final 10 - 20 cm of new snow led to active avalanche conditions Wednesday, producing mainly small storm and wind slab releases with a range of triggers. These ranged from 10 - 40 cm in depth while recent persistent slabs in the size 2 to 3.5 range, predominantly running on the late January crust, have featured 60 - 80 cm crowns. See the size 3.5 below. Persistent slab activity in particular is expected to resume or even intensify as warming tests the snowpack.
A melt-freeze crust or moist snow now glazes the surface on solar aspects and, by Friday, below about 1900 m. The depth of affected snow should increase over the coming days and crust recovery may be weak. This process will affect the upper part of 30 to 50 cm of settling recent snow, which is wind affected at higher elevations and may overlie faceted snow or surface hoar where sheltered.
Two other key weak layers are present in the mid snowpack: a surface hoar or thin crust from mid-February buried 40-60 cm deep, and faceted snow/surface hoar/crust from late January buried 60-90 cm deep. These layers have been active during recent storms and are expected to produce avalanches as warming tests the snowpack.
Thursday night
Partly cloudy. 15 to 25 km/h west ridgetop winds. Freezing level remaining near 2000 m.
Friday
A mix of sun and cloud. 10 to 15 km/h west ridgetop winds. Treeline temperature 4 °C. Freezing level to 2300 m, rising overnight.
Saturday
Sunny. 15 to 20 km/h southwest ridgetop wind. Treeline temperature 7 °C. Freezing level to 3000 m.
Sunday
Sunny. 5 to 10 km/h variable ridgetop wind. Treeline temperature 7 °C. Freezing level 2500 m - 3000 m.
More details can be found in the Mountain Weather Forecast.
