Start small and gather information about the depth and reactivity of new snow on Thursday. Signs of instability like shooting cracks or recent avalanches would be good reasons to stick to simple terrain.
Moderate snowfall is expected to form a widespread to storm slab problem for Thursday. The current warming pattern will promote slab formation and slab reactivity.
Wednesday night: Cloudy with a final storm pulse bringing 10-20 cm of new snow. Moderate to strong southwest winds.
Thursday: Clearing to a mix of sun and cloud. Light northwest winds. Treeline high temperatures around -4, cooling over the day.
Friday: Mainly sunny. Strong southwest winds becoming extreme by evening. Treeline high temperatures around 0, cooler at lower elevations with a likely temperature inversion.
Saturday: Cloudy with isolated flurries. Strong southwest winds. Treeline high temperatures around -5.
We don't yet have reports from Tuesday, but there was likely an uptick in natural activity in areas that saw the higher end of new snow amounts. This should be more widespread on Thursday with up to 30 cm of new snow expected.
Reports from Monday included several more observations or recent natural wind slab releases with sizes ranging from 1-2 (small to large). North aspects were highlighted.
There are very few reporting operations in this region, so remember that a lack of observed avalanches does not necessarily mean that there is a lack of avalanche activity. If you are getting out, please post your observations to the Mountain Information Network!
Another 10-20 cm of new snow is expected by Thursday morning, adding to 20-50 cm of snow the region has received since Sunday. Pine Pass and the MacGregors have been snowfall hot spots. In exposed areas at treeline and above, a forecast switch to northwest winds could promote wind slab formation across a wide range of aspects.
Our new and recent snow collectively overlies a previously wind-affected surface comprised of old hard wind slabs, sastrugi, and areas stripped back to the ground or old crusts. Snow at this interface was significantly weakened during the cold snap, which means the bond here remains in question. This is especially important as more new snow and warming make their way into the region.
A crust that was formed at treeline elevations and below in early December has been reported in parts of this region. It can be found down 50-100 cm. Although this layer is now considered dormant in the region, a large amount of new snow or warming temperatures have the potential to wake it up, and larger avalanches in surface layers or natural cornice falls may have potential to step down to this layer in isolated areas.
The base of the snowpack is composed of crusts and weak faceted grains, particularly in thin snowpack areas east of the divide.
