Vail & Summit County

Avalanche

Mike Cooperstein, Scott Toepfer · Dec 20, 2015 · Vail & Summit County

Weather

Saturday December 19, 2015 was the first day since December 13th without snowfall. Temperatures rose from a morning low of 21 degrees Fahrenheit to a high of 29 Fahrenheit at 13:00 hours under scattered to broken clouds. Northerly winds began to shift to the southwest mid-morning and were 12 to 14 mph gusting into the mid 30's by mid-day on the 19th. From December 13 to 19 the area received 6 to 8 inches of new snow. Weather was snowy on December 20th and we received two inches of additional snow in the time we were in the field.

Snowpack

10cm of wind deposited snow; 5cm broken and fragmented new snow; A layer of small rounded grains ~15cm thick; A thin crust; A layer of well developed cupped striated, chained faceted 3-5mm grains; A thin crust (which was the bed surface mor much of the previous days avalanche; 3mm moist depth hoar to the ground.

Avalanche

We were in the area to investigate a skier triggered avalanche from December 19, 2015. That avalanche was categorized as a SS-ASu-R2-D1.5, a soft slab avalanche triggered by a skier, small relative to what the path could produce, but large enough to possibly injure a person. You can view the report on the web page. http://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=37404 A medium size compared to the path, hard slab avalanche, triggered naturally, and able to bury or kill a person (HS-N-R3-D2.5) was observed above treeline on the Carter Gulch northern headwall. This slab was estimated at 3 to 4 feet deep, by 1,000 feet wide, running a max length of 400 vertical. It likely ran on December 17th.