BNSF RAILWAY AVALANCHE SAFETY VOLUNTARY FIELD OBSERVATIONS
SHED 7 East
Toured into the starting zone of Shed 7 East today. Surface snow conditions were scoured on westerly and southerly exposures above 5200 feet elevation. No shooting cracks, collapsing, or audible failures. Travel conditions were good on ascent and descent. * Windloading has been substantial above 5,400 feet elevation in the past few weeks on easterly aspects in the Program area… Terrain features normally recognizable in starting zone locations have been buried or filled in. In numerous locations, surface snowpack slope angle in starting zone locations have been reduced appreciably and in some locations, cornices have grown impressively large (Please refer to attached photo).
Below 5,200 feet elevation, air temperatures averaged in the low 30s F and above 6,000 feet averaged in the lower 20s F. Light to moderate west winds at elevations above 5,400 feet. Wind loading occurring on easterly aspects. Intermittent snowfall throughout the day with no measurable accumulation.
Snow profile was conducted in the starting zone of Shed 7 East on a 32 degree, south easterly aspect (120 degrees). Profile location was at 6323 feet elevation.
Snowpack was dry throughout with a depth of126 cm and no significant T gradient. However, a significant temperature gradient was observed between the air T (-6.7 degrees C) and the snowpack surface (-5.3 degrees C).
126-116 New Snow .50mm
116-90 Rounds. .50 mm
90-81 Decomposing Facets. .50 mm. CT12 Q1 CT8 Q1 & ECTN
81-15 Rounds 0.75 mm
15-0 Depth Hoar 2.00 mm CT19 Q2- & ECTP 27/ ECTN
As noted, we did get propagation in an ECT in the basal depth hoar… Actually, we are unsure if this was propagation or collapse… Either way, the depth hoar interface is currently well supported by a thick slab of rounds immediately above it. From a Program perspective, the depth hoar layer interface provided the greatest level of interest/ concern for this profile location. From a backcountry touring perspective, the 90 to 81 layer was of greatest concern and likely involved with the intentionally triggered avalanche we initiated (read below).
Intentionally triggered soft slab (SS-ASc-R2D1-I) in Test Slope 2 on a 40 degree southeasterly exposure at approximately 5,600 feet (1697 m) elevation. This released on the interface between newly wind loaded snow and the old snow surface beneath it. Slab thickness averaged 30 cm and width was approximately 20 m. Debris ran full path of test slope.
No natural avalanche activity observed.
BNSF AVALANCHE SAFETY FIELD OBSERVATIONS SUBMITTED TO THE FLATHEAD AVALANCHE CENTER AND GLACIER NATIONAL PARK ARE BEING PROVIDEDED IN ACCORDANCE WITH THE TERMS AND CONDITIONS SPECIFIED GLACIER NATIONAL PARK SPECIAL USE PERMIT.
THESE OBSERVATIONS REPRESENT SITE SPECIFIC INFORMATION INTENDED FOR THE BNSF AVALANCHE SAFETY PROGRAM AND IN NO WAY ARE TO BE CONSTRUED AS A PUBLIC/ RECREATION AVALANCHE FORECAST.