South Fork Eagle River:
Red flags (obvious signs of instability):
- Recent heavy snowfall
- Wet, gloppy surface snow (upside down with drier, lower density snow below wetter, denser snow)
- Whumphing (collapsing)
- Human triggered persistent slab avalanche (SS-ASu-R2-D2-O) N-NE aspect off The Nipple
- Recent avalanches reported in the 3 Bowls area
- Obscured skies with light SE winds, alpine temps in the upper 20s to lower 30s, and light snowfall
- Light rain below ~2000′, wet to moist snow above
- 1’+ recent snow
- Upside down with more recent heavier, denser, wetter snow on top of light, dry snow from Friday-Saturday
- Generally gloppy and heavy with 3″+ moist to very moist snow on top
Hard, slow, and boot top or deeper trailbreaking through heavy snow. Numerous “whumphs” (collapses) in more heavily loaded areas, especially where snow was noticeably “punchy” with heavy, dense snow on top of looser, drier snow.
Human triggered avalanche (SS-ASu-R2-D2-O) witnessed from the trailhead. At least five people and one dog involved. Three people caught. One escaped quickly to flank. Two people carried about ~400-700′, but remained on surface. Moist snow avalanche was relatively slow moving. Everyone accounted for and no injuries or lost gear. Avalanche triggered from ~3200′ above and to the north of Hunter Pass Hunter Pass and SE of The Nipple on a cross-loaded gully sidewall N-NE aspect. Avalanche crown estimated to be ~100′ wide with a depth up to 3+’. Avalanche ran ~700′. Propagation appeared to initiate either within recent upside down snow, at new-old snow interface, or at a weak layer near the old snow surface; but avalanche propagated to deeply buried persistent weak layer (likely depth hoar and basal facets) as it wrapped into the cross-loaded gully and released near the ground.