Trip Planning for Island Park

The snowpack turned out to be more stable than I had expected. 90cm at elevation with descent cohesion. 10cm of new snow. Compression test resulted in a CTN. Extended column test resulted in ECTX. I am still wary of some wind loaded drifts that could crack or collapse but didn't find any. There is a weak faceted layer about 20cm down that could become a problem with a new load of snow.

90cm at elevation with descent cohesion. 10cm of new snow. Compression test resulted in a CTN. Extended column test resulted in ECTX.

ECT Test Results

Location: 300ft below Lionhead Peak

Elevation: 9250ft

Aspect: East, 88deg

Slope Angle: 33°

Total Snow Depth: 115cm

Result: ECT 22, at 15cm deep (new snow interface).  At this location the top 10cm of new snow was loose, then 5cm of new snow formed into wind slab.  Remaining 100cm of snow ECTX, well consolidated, no visible layers, approx 2F hardness to the ground.  

Comments: Failure at the new snow interface seemed very spatially dependent.  We had an ECT 11 in another area. 

Skied multiple locations along Lionhead Ridge over 3 days, NE to E aspects.  Our observations were in line with the avalanche reports.  New snow was generally 15cm deep and weakly bonded to the existing snowpack.  There was minimal wind transport during this time along the more protected NE aspects along the ridge line, so the snow was not particularly wind loaded or consolidated.  Even so, there was multiple instances of small natural loose snow avalanches on steeper aspects or terrain rollovers.

A snowmobiler noted cracking of the snow surface on the south face of Reas Peak out of Island Park. The wind crust was 3-4" thick and had facets underneath which aided the propagation.

We went down to Sawtelle Peak to do some work on one of our weather stations. Lots of rime on the peak.

While we were down there, we dug a pit to see how the snowpack is developing in the Island Park area. Some wind drifting, but not super dramatic. Dug on an east aspect around 9000 ft off the Sawtelle Peak Road. Snowpack depth was around 4 ft. ECTX results.

It's still early season, but for now we're happy with how the foundation of the winter's snowpack is shaping up.

During the annual setup for the Hellroaring Hut we underestimated the amount of snow based on snotel readings in the area. 18”+ in shaded areas around 7,500’ and < 6”-12” on solar aspects, steep solar aspects were already melting out and bare ground was being exposed. Thick sun crusts we’re already formed on most solar aspects, while shaded regions remained unconsolidated. Lots of surface hoar growth in the meadows. Long story short, it’s good to know the relationship/aspect of the Snotel sites you trust for data mid winter, going forward although wary season snowfall was limited there will likely be some interested surfaces to contend with in the Centennial Range until the snowpack gets deep enough to begin the healing process…

-Sam

An observer saw evidence of wind loading creating the conditions for avalanches in the Bridger Range on Sunday. Cracking is an indicator of instability. The observer noted that the relatively small drift he saw was "nothing consequential," but this shows that unstable drifts are forming. They will be more consequential where there is more snow and as the wind creates larger drifts. 

Ian and I completed the setup of a SNOdar snow depth sensor on Sawtelle Peak in the Centennials. Located at 8800 feet elevation. The sensor will record total snow depth and 24 hr snowfall. Data will be displayed on our website soon at: http://www.mtavalanche.com/weaterh/stations/sawtelle-snow.

The snowpack is non-existent in this area. I think the only snow I could see was the north summit snowfield on Lone Peak from the drive.