Continued wind slab development on Ralston

Location Name: 
Echo Summit Area
Date and time of observation: 
Wed, 04/19/2017 - 12:00
Location Map: 
United States
38° 49' 48.1908" N, 120° 5' 31.1352" W

Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Rapid warming
Obvious avalanche path

Observation made by: Professional Observer
Snowpit Observations
More detailed information about the snowpack: 

Pic 1: On near treeline S aspects sheltered from wind, new snow was deep enough to just have begun transitioning to melt/freeze. On similar slopes below treeline, this recent layer had already become Very Wet and was much less consolidated than the snow above or below it was. Near and above treeline, on slopes exposed to wind, new snow was only a few cm deep on top of supportable, consolidated snow.

Pics 2 and 3: A thin "firnspiegel" on open slopes mid-day indicated the radiation in/out balance was close to equal on sunny aspects. Moderate, cool, SW winds influenced this balance. Winds became Strong at ridgetop, where ice remained on trees and rocks from yesterday's precip.

Pics 4 and 5: Ongoing wind transport observed on N aspect of Ralston/Talking ridge. This recent crown likely occurred yesterday, and was mostly obscured by subsequent wind transport. A CT and 2x ECTs adjacent to this crown showed ongoing instability at a similar height today (Hard taps down 25cm on decomposing precip particles). Overlying slabs "popped off" on each ECT, leaving a very clean and planar sliding surface. No intact graupel observed at this location (pin drop).

The expected Wet Loose instabilities were easy to initiate on sunny, low elevation test slopes in the afternoon. Numerous recent Wet Loose avalanches were observed near ridgetop, but I suspect these were from yesterday afternoon.  

Snowpack photos: 
Weather Observations
Blowing Snow: 
Cloud Cover: 
50% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Air temperature trend: 
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 

Dark cumulus clouds gathering in the afternoon, observed to have a cooling effect rather than greenhousing.