BNSF Avalanche Safety Field Observations

Toured up the south face of Running Rabbit Mountain on the ridge separating the Shed 11 and Shed 10.7 avalanche paths. High point was at the Shed 11 weather station. After some maintenance on the station we descended the Shed 11 path back to the rail grade.

Broken skies, no precipitation, and light west-northwest winds all day. Air temperatures rose from just below 0°F in the morning to the mid-20s °F by the afternoon at the Canyon floor and into to the mid-teens °F above 6000 feet elevation. 

• Found variable snow conditions on the tour.
  • The Feb 8 crust extended up to about 6000 feet.
  • On the Shed 11/10.7 ridge above 5000 feet elevation the recent east winds had raked the slopes down to the Feb 8 crust.
  • Westerly aspects had recent wind slabs on top of the Feb 8 crust and varied in depth from 10 cm to over 1 m thick.
  • Observed some minor cracking in these wind slabs (1-2 m) in length.
• Dug our first snowpit at 5400 feet in the Shed 11 path on a wind-loaded SW aspect.
  • Recent wind slabs 50-75 cm thick rested on top of the Feb 8 crust. Multiple ECTNs within these wind slab layers.
  • Found another crust 80-100 cm beneath the surface. This crust was not reactive in the first Extended Column Test, but was in the second with ECTP24 on a thin layer of facets on top of the crust.

• Dug a second snowpit in the Shed 11 path at 6200 feet on a SE aspect.
  • HS=158, 36° slope angle, pit profile attached (photo 1).
  • Two Extended Columns test resulted in multiple ECTNs in the upper 60 cm of the snowpack, but no propagating fractures.
  • The Feb 8 crust was buried 50 cm deep at this location.
  • The Thanksgiving crust was absent here but the early December facets were present at the bottom of the snowpack.  

• Yesterday a recent wind slab was observed in Path 1163 with debris running 2/3rds path and terminated above the rail grade.
• No other recent avalanche activity observed.