Shed 9, Middle Fork 3/26/13

BNSF RAILWAY AVALANCHE SAFETY

VOLUNTARY FIELD OBSERVATIONS

 Steiner

 3/26/13

Shed 9 SZ

GENERAL INFORMATION:

Toured up Shed 7 West avalanche path to the Shed 7 ridge and then west into the Shed 9 Starting zone. Ascent conditions were fair and travel was easy- with the use of ski crampons. Descent was fair as surface snow had warmed to moist/ wet consistency. Surface roughness increasing substantially at lower elevations. Vegetative and terrain hazards becoming more prevalent at snowpack surface.

WEATHER OBSERVATIONS:      Mostly clear skies today with a few scattered clouds.    Light west winds.      Air Ts on Canyon floor were in the lower 20s F in the AM and warmed into the mid-30s F by afternoon.  Air Ts at approximately 6000 feet during the afternoon hovered around 32 F.    Solar input significant today…SNOWPACK OBSERVATIONS: Full profile conducted in the starting zone of Shed 9 on a south/ southeast aspect (140 degrees) 30 degree slope at an elevation of 6800 feet (6800’). Snowpack depth 116 cm and moist in upper most layer and dry for remainder of snowpack. Significant Temperature gradient existed in the upper 16 cm of the snowpack.Upper and mid snowpack at this location was relatively supportive and consisted of rounded grains, a 10 cm melt/freeze crust, and decomposing facets- beneath the MF crust. No significant stability test results on these layers.Greatest concern at this location is related to depth hoar found in the lower 47 cm of this profile. This layer is 47 cm in height, 4F+ in hardness, comprised of 3mm depth hoar and is adjacent to a P hard ice crust/ lens. This layer/ layer interface was not reactive in ECT tests but failed with hard force Q2 shears in CT stability tests.*Please refer to attached Snow Profile.Similar to last week’s observation in the Shed 5 starting zone (March 19th, 2013) we feel the mid-pack at this location appears to be providing supportive structure to the snowpack.

AVALANCHE OBSERVATIONS:

One relatively small soft slab avalanche that had previously released was observed in the starting zone of Shed 9. Debris associated with this slab terminated in the upper 1/3 of the Shed 9 SZ.

 

BNSF AVALANCHE SAFETY FIELD OBSERVATIONS SUBMITTED TO 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.

 

shed9_3_26_13

Shed 9 Start Zone 3_26_13

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