Observation: Mule Hollow

Observation Date
01/12/2018
Observer Name
B

Region:

Location Name or Route
Mule Hollow/West Willow
Weather
Sky
Overcast
Precipitation
Light Snowfall
Wind Direction
Northwest
Wind Speed
Moderate
Weather Comments
Strong WNW winds throughout the night and into the mid morning hours, even at 8000 feet in BCC in a typically quiet location. By 1200 the winds appeared to settle down to light and only be present on the ridgelines. Wind blown and or transport was moderate up until noon with cornices building and the windward slopes being wind swept. Temperatures remained in the low to mid 20's above 8500 feet, and the skies were overcast until 1400. At that point they were broken.
Snow Characteristics
New Snow Depth
2"
New Snow Density
Low
Snow Surface Conditions
Powder
Dense Loose
Wind Crust
Snow Characteristics Comments

Fortunately the sun did not come out until mid afternoon and even down at 8000 feet the snow remained cold and dry. New snow overnight and into the morning hours accumulated to 2 to 3 inches, and it consisted of mixed forms and graupel. This new snow combined with the denser snow that has fallen in the past 72 hours provided an excellent turning base on low and moderate angled slopes. Of note, the rain crust from earlier in the week appeared to be between 8500 and 8700 feet; and in the transitional zone between 8600 and 9000 the overall dampness from this warm and wet event made for a good spongy based up carving surface. From 8600 down, the rain crust has helped riding conditions, and stability immensely. HS from 8600 down is only 45 to 50 cm/18 to 20 inches, yet because it is now frozen and completely supportable, the 2 to 4 inches of new from the past 48 hours has made for great/relatively safe traveling conditions down to the trailheads. 

Red Flags
Red Flags
Recent Avalanches
Wind Loading
Cracking
Poor Snowpack Structure
Red Flags Comments
During the morning hours the winds were helping to build small/sensitive cornices on the northerly facing ridgelines, and loading the upper starting zones. MInimal cracking was observed when dropping cornices, but no collapsing and or avalanching was observed. West Willow's terrain did not allow any of these cornice releases to impact the slopes below with enough force. As recent as on Thursday, similar slopes (with aspects, elevation, and location) were still getting remote triggering, but all conservative/safe efforts at initiating this kind of reactivity were negative.
Avalanche Problem #1
Type
Persistent Slab
Trend
Same
Problem #1 Comments

Despite these unsuccessful efforts to provoke the multiple buried weak layers, and overall poor snowpack structure on the northerly and easterly facing terrain, the setup still remains in place for a propensity for propagation and large dangerous avalanches. 

Avalanche Problem #2
Type
Wind Slab
Trend
Decreasing Danger
Problem #2 Comments

The recipe for reactive and sensitive wind slabs appeared in place during the morning hours when the WNW winds were actively loading starting zones. As the winds are forecast to remain light for the next few days, this concern should decrease in likelihood. 

Danger today appeared to continue to be a high consequence Moderate; and due to the nature of the persistent weak layers in our snowpack this concern may be in place for a while. 

Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Moderate
Snow Profile Coordinates