Weak layers in the upper snowpack are primed for human-triggered slab avalanches.
Evaluate snow and terrain carefully and remember; conservative terrain choices are your best defense.
Recent snow and wind have formed wind slabs in leeward terrain features at upper elevations. They may be especially reactive where they sit over a slippery crust or surface hoar.
A widespread weak layer of surface hoar/crust/facets is buried around 30 to 40 cm deep. There have been several cases of skiers being surprised by it recently. Most were on north to west aspects near treeline.
On Sunday, several human-triggered storm slab and persistent slab avalanches were reported.
Storm slabs releases were roughly 15 cm deep, with deeper releases in wind loaded areas.
Persistent slab releases were roughly 30 to 40 cm deep, failing on the late-January layer of surface hoar/facets/crust.
Roughly 15 cm of new snow (wind affected at upper elevations) overlies a complex upper snowpack.
A widespread breakable crust sits beneath the new snow, on all but the highest north aspects. At mid elevations, it may be topped with surface hoar crystals, making for a weak bond.
Another widespread weak layer is buried 30 to 40 cm deep. It formed in late January and consists of surface hoar on a melt-freeze crust, with a thick layer of facets below.
These layers are expected to become increasingly problematic as they get buried deeper.
The mid and lower snowpack remain well settled, with no significant concerns at this time.
Monday Night
Cloudy. 5 cm of snow. 20 km/h southwest ridgetop wind. Treeline temperature -8 °C.
Tuesday
Cloudy. 1 cm of snow. 20 km/h southwest ridgetop wind. Treeline temperature -8 °C.
Wednesday
Mostly sunny. 20 km/h northwest ridgetop wind. Treeline temperature -7 °C.
Thursday
Sunny. 20 km/h west ridgetop wind. Treeline temperature -5 °C.
More details can be found in the Mountain Weather Forecast.
