Southern Trailhead Survey and Avalanche Observations

SNOWPACK OBSERVATION
Southern Trailhead Survey
Submission Info
Forecaster
Saturday, March 24, 2018 - 2:45pm
Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Obvious avalanche path
Southern Trailhead Survey 37° 14' 4.812" N, 118° 36' 17.4384" W
Snowpit Observations
More detailed information about the snowpack: 

A trailhead inspection south of Mammoth this afternoon, looking for evidence of avalanches from the 3/21-22 cycle and recent Wind Slabs.

Throughout the afternoon: extensive intense SW wind transported snow near and above treeline (~9000’) from McGee north to Mammoth with strong downslope winds, especially the exposed front country.

South of McGee, moderate to intense wind transport from SW flow aloft, more confined to above treeline. Snow plumes began to dissipate slowly during the late afternoon, with the strongest transport confined to the above treeline after 700ish, which appeared to be easing back toward moderate. McGee north to Mammoth, moderate to intense snow transport continued throughout the early evening. Early evening: light snowfall as you approached Mammoth above ~7300’. Mountains obscured with precipitation and/or wind transported snow.

Avalanches:

Noted extensive debris from the previous avalanche cycle (3/21-22) south of Mammoth to McGee. Along the front country north of Convict Lake to Laurel Lakes Basin, saw 3D3’s, 2D2, elevations N-NE, elevations ~9000’-10000’. Likely missed others but the active windloading was obscuring visibility. Debris concentrated in the gulley features. Windloading continued throughout the day into the early evening.

McGee had what appeared to be 4 D3’s, 1 D3+, 1D4, the last two traveling a good distance out onto the sagebrush apron but possibly as low as ~7200’. Note: very active windloading throughout the afternoon into the evening.

South of McGee: the front country had a notable lack of debris fro the 3/21-22 cycle. Likely avalanches more confined toward the Crest, not immediately visible from 395. Wind transported snow visible, but more confined  to above treeline.

Snow coverage:

Aspendell (~8300’) – 24cm (~9”) @ the gate.

South Lake Trailhead (~8400’) – 27cm (~10.5”) @ the gate.

Rock Creek (~8900’) – 31cm (~12”) @the gate. Most I’ve seen all this season.

The dense snow will help resist the intense spring sun, which will slow melting and provide some protection from underlying objective hazards (logs, rocks, stumps, etc.), especially below ~9000’.

 

Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
50% of the sky covered by clouds
Air temperature: 
Wind Speed: 
Moderate
Precipitation: 
Snow
Air temperature trend: 
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

Mostly clear from Tom's Place south with extensive snow transport throughout the Alpine from SW winds. McGee north to Mammoth, clouds over the Crest, mostly clear elsewhere. Intense wind traonsported snow treeline and above. Light snowfall Mammoth north, as evning approached.  

ESAC receives support from ...