Public Observation #2022-874
Submitted:December 7, 2022 3:17 PM
Observation Date:December 6, 2022
Zone or Region:Central Cascades
Signs of Unstable Snow
ObservationsToured out to Ball Butte yesterday. Leaving the snowmobiles, we calculated ALPTRUTHs as:
Avalanche in last 24 hours: No
Terrain traps: No
Unstable snow: No
Thawing instability: No
Dug a pit on a lower section of an East/Northeast-facing slope, near the skin track that takes you to the East bowl. Conditions at the time of our test pit were:
Elevation: 7744 ft.
Test pit included a column test resulting in CT4, fracturing at 5cm below the surface, what we deduced was wind deposited snow on top of the last storm slab. Total depth was 125cm.
Observing no signs of whumphing/cracking on our skin up, we decided to ride the East bowl. Rocks hidden below the surface when dropping in were aplenty. We had no issues once in the bowl nor towards the bottom.
Skinned around to the North Bowl and ran into another party who had dug a North-facing pit ~100 yards North of Ball Butte summit. They said they ran an extended column test fracturing on that same wind slab, ~5cm below the surface. They added, with more force (not sure how many hits to the shovel) they observed propagation across the buried surface hoar roughly a meter below the surface. They stated they also ran a Rutschblock test, stating that test failed on that same buried layer, roughly 1 meter below the surface.
Feeling confident we would not create enough load to initiate that buried layer, we rode 2 laps off the summit into the North bowl and 2 more laps into the East bowl. Snow began to accumulate more heavily on the skis on the skin track, but the snow was felt fast and light while riding. Picture attached is of the East bowl after our last lap.