Wind Slabs on Red Cone

SNOWPACK OBSERVATION Mammoth Lakes
Submission Info Forecaster Friday, December 22, 2017 - 12:30pm

Contributor

Clancy Nelson

Red Flags:

Whumphing noises, shooting cracks, or collapsing

Recent loading by new snow, wind, or rain

37° 35' 54.24" N, 119° 1' 23.88" W

See map: Google Maps

Snowpit Observations

More detailed information about the snowpack:

Toured up Red Cone to test the recently formed wind slabs. Test slopes in sheltered areas, on N through E aspects, between 9100' and 9580' showed no sign of slab cracking, but did show the potential for small loose dry sloughing. 1 exposed, cross-loaded ridge at 9400' (NE aspect) had some localized cracking in my kick turns. Test slopes at the top of Red Cone were a different story. Jumped on NW, SW, and ENE aspects between 10,171' and 10,371' in wind deposited snow. W and NW sides of ridges had shooting cracks over 2m long (see stomping video). These aspects seemed to have more widespread wind slabs. Slabs on SW and ENE aspects had more localized cracking, were harder, and were more stubborn. Slabs on these aspects were also confined to specific, favored areas and were less pervasive across the terrain. Quick snow profile and snowpack tests at 10,161' on an ENE aspect: ECTPs and CTVs on facets under wind slabs (see attached profile and snow pit video).

Had about a 50'x50' area whumph in the trees at 8900' above the back side of Horseshoe Lake on a NW aspect.

Snowpit or crown profile photo or graph:

Snowpit videos (tests, etc):

Any other comments about the observation or links to outside pages that have more info on the observation:

Coverage is still poor below about 9400' in the Lakes Basin. 20-30cm below 9500'. Below about 9000' there's just enough to make it look like there's snow, but the ground is waiting just underneath.

Weather Observations

Blowing Snow:

Cloud Cover:

25% of the sky covered by clouds

Air temperature:

Above Freezing

Wind Speed:

Calm

Precipitation:

None

Air temperature trend:

Warming

Wind Direction:

Accumulation rate:

More detailed information about the weather:

Warmer today. 5 deg. C at 11am at 8900' where the surface snow was moist and sticky. At 1215pm Tair = 2.5 deg. C at 10,161' but the snow was still dry winter snow.