Buried surface hoar around Donner Summit

Location Name: 
Castle Pass/Andesite Peak
Region: 
Donner Summit Area
Date and time of observation: 
Mon, 01/22/2018 - 12:00
Location Map: 
United States
39° 21' 27.0648" N, 120° 21' 56.97" W
See map: Google Maps
US


Red Flags: 
Recent loading by new snow, wind, or rain
Observation made by: Educator at Donner Summit Avalanche Seminars
Snowpit Observations
More detailed information about the snowpack: 

Our observations today focused on wind slab development (only the most minor at summit of Andesite Pk) and the (now buried) surface hoar widespread over Donner Summit from yesterday.  Was it raining or snowing?  Yes.  Light snow showers early this morning gave way to mist and drizzle by 0900.  By 1000 a thin rain crust was widespread across the snowpack surface (save under the trees where the snow remained remarkably lighter).  Multiple (way cheaper by the dozen) tilt tests revealed the surviving surface hoar under 5-7 cm new snow.  Some clean shears, most not.  A backlit thin section revealed the feathery crystals in profile, otherwise hard to ID with my bulky opposable thumbs.  Soft on soft.  By 1400 a bit of open blue sky.  No signs of instability today.

Snowpack photos: 
Weather Observations
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Light
Precipitation: 
Mixed rain and snow
Air temperature trend: 
Warming
Wind Direction: 
Southwest