Human triggered avalanches are possible on steep slopes at higher elevations. Be extra cautious in wind-affected terrain.
A weak frontal system will form new wind slabs on north and east aspects, while old stubborn buried slabs may exist on all aspects in steep higher elevation terrain.
A weak front crosses the region on Friday night.
FRIDAY NIGHT: Cloudy with some scattered flurries and 5-10 cm of new snow, strong south wind, freezing level drops to valley bottom with treeline temperatures dropping to -8 C.
SATURDAY: Cloudy with some isolated flurries, light southwest wind with some moderate gusts, freezing level around 1400 m with treeline temperatures around -5 C.
SUNDAY: Cloudy with some isolated flurries, light south wind, freezing level around 1200 m with treeline temperatures near -5 C.
MONDAY: Mostly sunny, light wind, treeline temperatures around -7 C.
Warm sunny weather between Wednesday and Friday resulted in a widespread cycle of wet loose avalanches on sun-exposed slopes. These were mostly small (size 1-1.5), but a few large (size 2.5) wet avalanches were also reported. Heating also caused some cornice and ice falls. Clouds and cooling temperatures will heal these problems.
The primary concern this weekend will be wind slabs, both old ones lingering on all aspects and new ones forming on north and east facing slopes. A notable human triggered avalanche from Wednesday provides a good example of the old wind slab problem, as a skier triggered a size 3 avalanche in a steep south-facing couloir in Glacier National Park (MIN report).
A dusting of new snow will accumulate above moist and crusty interfaces that formed during the recent warm up. Some deeper accumulations can be expected in lee terrain features. High shaded terrain will have a mix of soft snow and some old buried wind slabs. 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 crusts that was buried in late January (80-120 cm deep).
