Muddy Mercury

Avalanche conditions

• Rapid temperature rise to near or above 0°C or wet surface snow.

The South Rockies team enacted a backup plan and went for a tour up the Mercury Basin today. We intended on going up the Little Sand area, but a lack of snow down low made it impassable for our machines. It was a warm day and mostly sunny with a few convective squalls.

The access to Mercury/Mcdermott is good from the cat shed. Isothermic snow down low kept the machines cool on the trail. Up past the Mercury cabin the warming has had a significant impact on the ski quality, breakable crust and ski pen of 10-30 cm in moist snow all the way to 1800m.

We dug on an east and west aspect at 1800m. Height of snow is between 260-300 cm. The persistent weak layer is down 75cm and still has preserved surface hoar up to 15mm on a supportive crust. We had CTH24, ECTX, RB6 WB, and PST 35/100 end on this layer.

We observed no signs of avalanche activity. Although this layer is not giving obvious red flags while travelling on skis/snowmobile, the structure for large avalanches still exists, and is still able to be triggered by humans. Shallow areas, buried rocks/trees, and thin to thick areas are all likely places to trigger this problem. In this area it is a low probability, high consequence problem, and we avoided skiing in avalanche terrain today.