Observation: Public
Observation Details
Name:
Andy HarringtonObservation Date:
February 19, 2021Submitted:
February 19, 2021Zone or Region:
West SouthActivity:
Skiing/SnowboardingLocation:
Cement BasinObserved Avalanches
Did you observe any avalanches?
YesAvalanche Type:
Hard SlabSize:
Size 2: Could bury, injure, or kill a personElevation:
6400'Aspect:
NEComments:
Crown was a day or maybe two old, so likely occurred on 2/17-2/18. Was close to 2 feet deep and was on a steep unsupported rocky slope.Photo:
Signs of Unstable Snow
Observations
Traveled up East Peak and down into Cement Basin to dig around and look at our layers of concern heading into the weekend and another atmospheric river event.
Found a slight breakable crust on slopes with a southerly tilt that receive direct sunshine. Closer to the ridgeline, there were areas of wind-stiffened snow and a few drifts that produced some cracking as I skinned. East aspects on the lee side of the ridgeline had somewhat freshly built cornices and some wind-loaded slopes just below them.
Dug around 6200' on a NE aspect down in Cement Basin. HS was 237. Found that the 2/11 was ~67cm down, with another layer ~59cm down. These two layers produced inconsistent results, taking turns breaking CTH. Most of the failures on the lower layer (2/11) were sudden and planar. Both layers had some faceting stellars, with the 2/11 being more pronounced. ECTs and PSTs did not propagate a failure on either layer despite some failures on the 2/11.
The Mid-January crust was down 123cm and still contains 0.5-1mm facets above the crust. Within and below the crust, there are larger facets, and the snow is very rotten. Deep Tap Tests produced sudden and planar failures on the 22 tap.
Media
