Avalanche: Mt Olympus

Observer Name
Grainger, Young, Collon
Observation Date
Monday, January 27, 2020
Avalanche Date
Monday, January 27, 2020
Region
Salt Lake » Mt Olympus
Location Name or Route
Mt. Olympus
Elevation
7,500'
Aspect
North
Slope Angle
42°
Trigger
Natural
Avalanche Type
Wet Slab
Avalanche Problem
Wet Snow
Weak Layer
Ground Interface
Depth
Unknown
Width
400'
Vertical
500'
Comments
Sunday night's precipitation came in warm in the valley floor, dumping rain ~40 degrees initially. This saturated areas of the low-mid elevation snowpack and in rocky/complex terrain created wet loose and wet slab issues. This was evident on N-facing Olympus from 6800' up as baseball-to-basketball sized moist debris piled up in certain couloirs/outruns.
The slide(s) shown likely occurred during the very early morning hours of Monday when warm precip had saturated the entirety of snow stuck to the steep rock slabs and released fully (hard to tell how many slides this consisted of and to what extent they connected). Though the rock slab bed surfaces were partially visible, the colder early AM snowfall obscured them with a few inches of new.
As we traveled through the area a solid band of small-grained graupel created noisy loose dry movement from 10-11:30AM. Complex terrain and funneling effects of North Mt. Olympus amplified this (video below) and produced continuous graupel rivers.
**Underneath of cliff bands and other areas of graupel-pooling should be regarded with caution as this week's new snow accumulates on top**
Comments
Rock slab like this served as the bed surface for saturated old snow to slide.
Comments
Consistent high-rate graupel stream.
Video
Coordinates