Lookout for fresh storm slabs reactive to human triggers in wind exposed terrain at treeline and above.
Confidence
Low - Due to the number of field observations
Weather Forecast
FRIDAY/NIGHT: 5-15 cm new snow expected by Saturday morning / Moderate to strong southwesterly ridgetop winds.SATURDAY: Mostly cloudy with isolated flurries / Light to moderate southwesterly ridgetop winds / Freezing level around 1000 m.SUNDAY: Mix of sun and cloud / Light northwesterly ridgetop winds / Freezing level valley bottom.MONDAY: Mix of sun and cloud / Light to moderate westerly ridgetop winds / Freezing level valley bottom.
Avalanche Summary
On Thursday, explosive control near Golden triggered several size 2 storm slabs ranging 15-45 cm deep. On Tuesday, in the Dogtooth range a skier was caught in a size 2 storm slab on a northwest facing slope at 2350m. The skier was uninjured in the avalanche which was about 40cm deep and 180m long.We currently have very limited observations in this region. Please submit your observations to the Mountain Information Network (MIN).
Snowpack Summary
Last week, the November 23rd crust formed as temperatures cooled and the rain-soaked snow surface froze. Since then, 20-60cm of snow has fallen at treeline and above with moderate to strong southwest winds, creating storm slabs sitting on a crust. Two other layers have been reported in the snowpack: 1) The Halloween crust (down 100cm at treeline elevations) and 2) The November 10th surface hoar / facets (down 80cm at treeline elevations). We have very little information on how reactive these layers are. In fact, we currently have very limited snowpack observations within this entire region and it is critical to supplement this information with your own observations.The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 150+cm in the alpine, 100-150cm at treeline, and decreasing rapidly below treeline where the primary hazards are rocks, stumps, and open creeks.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.