December 15

Cardiff, Mill B South, Mineral Fork

Elevations, Slope angles and aspects:
7’000-11’000, angles to 40°, all aspects

Avalanche activity:
One localized collapse mid slope upper Mineral Fork.

Slopes skied:
Keyhole entry into Cardiff, Upper Mill be South to Monte Cristo bowl, upper Mineral, Santiagos, out Mineral.

Snow surface and conditions:
A couple of inches of dense snow over a variable base was the predominant conditions. Winds have once again moved a bit of snow around especially at upper elevations. A rime-rain crust was found on north facing. This varied from eggshell thick near the top of Superior to an inch or so at mid elevations in Mineral extending a couple of thousand vertical into the drainage.

It disappeared at lower elevations in the melt zone.
The crust is overlying a lot of lingering faceted snow.

Overcast, windy and mild temperatures. Winds were in the 10-20 mph range.

No, pole probing provided needed info in the variable conditions.

Heavy dense snow, a rain-rime crust and continued winds provide a complex pattern. Snow at mid and lower elevations should remain stable, depending on bonding of old and new combined with amounts. Concern would be of a significant load on the fragile rime crust with faceted snow below. Collapse failure of the crust is a distinct possibility with enough new snow.

December 16

Grizzly, Upper BCC

Silver and Days Fork

Elevation, slope angles and aspects:

7500 to 10’400, angles to 40°+, all aspects

Avalanche activity:
Numerous soft slabs from a density change within the new snow, sluffing on every slope with an angle over 35° with a simple touch or ski cut.

Ski cut sluff slide

Slopes skied:
East bowl of Silver, Hideaway Park, Main Days and Banana Belt in Days Fork.

Snow Surface and conditions:
6-8” new snow overlying a wide variety of old snow surfaces, mostly crusted. A stiff rain-rime crust is widespread on most slopes. This is variable in thickness from an eggshell to quite stout depending on aspect and elevation, thickest on southerly and mid elevation off aspects. Snow was sluffing easily on the old surface, with a lack of bonding evident. There was also a natural slide cycle from a density change within the new snow.

Stress fractures found on east facing upper Days Fork.

Side view

Natural avalanche within new snow Main Days

Overcast with moderate temperatures. Very little wind after the event causing the new snow instability.

Snow pit:


A lack of bonding, old surface with new snow, created a widespread avalanche cycle, both sluffing and soft slab fractures. I’d expect a slight increase in bonding, however forecast snow combined with increased wind would probably promote continued slide activity. Potential for deeper slides into older layering will likely increase