Wind loading and slabs on SW and W aspects south of Mt. Lincoln

Location Name: 
Mount Lincoln
Region: 
Donner Summit Area
Date and time of observation: 
Mon, 01/14/2013 - 11:30
Location Map: 
United States
39° 16' 49.26" N, 120° 19' 50.34" W
See map: Google Maps
US


Red Flags: 
Recent loading by new snow, wind, or rain
Obvious avalanche path
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

NE winds along the ridges south of Mount Lincoln averaged 45-65 mph this morning and transported significant amounts of snow. Wind slabs existed on the NW-W-SW aspects near exposed ridgelines. These wind slabs measured up to 18 inches thick and extended up to 20 ft downslope from the ridgelines. The dense wind packed snow that comprised these wind slabs made them act as hard cohesive slabs. Below these wind slabs soft cold snow existed on top of a crust. Skier triggered cracking and snowpit tests indicated that the wind slabs have not bonded well to the softer snow and that fractures could occur as the soft snow fails.

Photo 1: Skier triggered cracking on a W facing aspect near 8000 ft.

Video: ECTP 12 Q1 - This test showed that fractures can propagate through the soft snow below the wind slabs. A second ECT (ECTP 13 Q1) as well as several hand pits confirmed this result.GPS coordinates match the location of the ECT in the video.

Along the ridgelines and on exposed N-NE aspects firm wind scoured surfaces existed.

Snowpack photos: 
Snowpit videos (tests, etc): 

2013 01 14 Lincoln 005

Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
Clear
Air temperature: 
Below Freezing
Wind Speed: 
Gale Force
Precipitation: 
Air temperature trend: 
Warming
Wind Direction: 
Northeast
Accumulation rate: 
More detailed information about the weather: 

In the morning wind speeds measured 45-65 mph with gusts to 82 mph. By noon the winds had decreased to 30-40 mph with gusts to 55 mph