Avalanche: Mineral Fork

Observer Name
Mark Staples / Trent Meisenheimer
Observation Date
Wednesday, January 20, 2016
Avalanche Date
Wednesday, January 20, 2016
Region
Salt Lake » Big Cottonwood Canyon » Mineral Fork
Location Name or Route
Mineral/Mill B Ridgeline
Elevation
9,000'
Aspect
East
Trigger
Natural
Avalanche Type
Soft Slab
Avalanche Problem
New Snow
Weak Layer
Facets
Depth
10"
Width
300'
Vertical
400'
Comments

Several Avalanches. The weakest layer seemed to be a layer of graupel mixed with facets. I think these facets formed on the surface maybe Monday night/Tuesday morning during clear cold weather. On both S and N aspects we found it. With the desnse and upside-down new snow on top, we got ECTP2 and ECTP4 on this layer. The long propagations on this layer suggested that some facets are present.

1) We triggered several small slides along the summer trial about 5 minutes from the truck. All seemed to be wind loaded by downhill winds. One notable one was triggered from 300 feet away! Even though a small slide, this is significant propagation. Also, there was one section of trail we didn't feel comfortable crossing. We descended the trail and skinned up through dense trees to regain the trail.

2) We spotted a natural avalanche once we gained the Mineral/Mill B ridgeline. It was about 8-10 inches deep. More importantly, it was about 300 feet wide. It was unclear if wind loading triggered it or if a cornice triggered it. Another was nearby about 50 feet wide.

3) We triggered a couple more slides. One by simply walking along the ridgeline and initiating a collapse that cracked the cornices and triggered a pocket about 50 feet wide. We triggered two more by dropping cornices which were very sensitive. The first was about 25 feet wide. The second cornice triggered slide was about 200 feet wide, 6-12 inches deep. We used the second slide as a way to safely descend to lower angled terrain back to the trail.

4) Lastly I triggered a small pocket along the summer trail. Sort of intentionally, but it pushed me downhill about 10-15 feet. It broke about 25 feet wide. This pocket was a small open area right next to our skin track when we bypassed a section of trail by skinning through dense trees. I was curious if it would slide, but was skiing down and didn't think enough about it before jumping onto the slope. Its always amazing how much power the snow has even very very small slides.

Comments

Cracking along summer trail

Comments

Avalanche along summer trail.

Comments

Cornice triggered slide that gave us a safe way to descend to less steep terrain.

Video