Shed 5, Middle Fork 3/19/13

 

3/19/2013

1730

SHED 5

STEINER

GENERAL INFORMATION:

Toured up the Shed 6/7 ridge to the starting zone of Shed 5. Travel conditions were fair on ascent and poor on descent… Breakable MF crust formed throughout the day and was prevalent on all but the most shaded aspects- which are difficult to find on a southerly aspect Program area.

WEATHER OBSERVATIONS:

Mostly clear skies today with a few scattered clouds.

• Light west winds in early afternoon- decreased after 1500.

• 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 30 F.

• Solar input significant today… Melt/ freeze crust established on all southerly and non-shaded easterly aspects.

 

SNOWPACK OBSERVATIONS: Full profile conducted in the starting zone of Shed 5 on a southeast aspect (110 degrees) 34 degree slope at an elevation of 5800 feet (5800’). Snowpack depth 98 cm and moist throughout. No significant Temperature gradients and not yet isothermal. Mid-pack is comprised of melt/freeze crusts and decomposing facets. No significant stability test results on these layers. Greatest concern at this location is related to depth hoar found in the lower 30 cm of the profile. This layer is 4F- in hardness and failed in both ECT stability tests conducted- WITH the entire back of the column cut out… ECTP15 and ECTP22. When an additional ECT was conducted, without cutting the column back wall into the depth hoar, we observed an ECTX on the depth hoar layer-upper snowpack interface.

Based on stability test results, the mid-pack appears to be providing supportive structure to the snowpack at this location. Also, based on these stability test results, we feel that IF the mid-pack support is rapidly compromised, the potential for full-depth avalanche activity exists.

AVALANCHE OBSERVATIONS: One small wet slab release on a low elevation (l4000’) northerly aspect cut bank of the Middle Fork Corridor. This avalanche occurred sometime yesterday afternoon. No other slab avalanche activity observed today. Wet loose surface snow activity was observed in many locations and all was relatively small in magnitude.

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 ADVISORY.