New snow, wind, and rising Freezing levels have created widespread and reactive storm slabs. Large human triggered avalanches are LIKELY at all elevations on Sunday and very large avalanches on deeper weak layers are possible.
Two persistent weak layers buried in early/mid Dec. are now 80 to 150 cm below the surface. The form and distribution of these layers are HIGHLY VARIABLE and have created conditions that can vary significantly from one valley to the next .
New snow, strong winds and rising freezing levels have created widespread storm slabs ripe for human triggers.
SATURDAY NIGHT: Snow; 10-15 cm. / Strong, southwest ridgetop wind / alpine low temperature -4 / Freezing level 800 m.
SUNDAY: Flurries; 3-5 cm. / Moderate, west ridgetop wind / alpine high temperature -6 / Freezing level 1200 m.
MONDAY: Cloudy with isolated flurries; 0-3 cm. / Moderate, southwest ridgetop wind / alpine high temperature -8 / Freezing level 800 m.
TUESDAY: Mix of sun and cloud / Light, southwest ridgetop wind / alpine high temperature -7 / Freezing level 1000 m.
On Saturday, a skier triggered a size 2 slab avalanche near the Gorge area. See the excellent MIN report Here.
Large human triggered storm slab avalanches are LIKELY at all elevations on Sunday.
Up to 20 cm of new snow, moderate to strong winds, and rising freezing levels on Saturday have created widespread storm slabs ripe for human triggers.
Two persistent weak layers buried in early/mid Dec. are now 80 to 150 cm below the surface. The form and distribution of these layers are HIGHLY VARIABLE and have created conditions that can vary significantly from one valley to the next. The first layer down around a metre has been primarily reported as small surface hoar.
The next layer has been reported as a thin freezing rain crust, surface hoar, or thick rain crust depending on elevation and location. As a result, diligent investigation of the snowpack is required to get a handle on local conditions. Forecast snowfall for the weekend may reignite avalanche activity at these deeply buried interfaces.
