Observations from Castle Pass and Andesite Ridge.

Location Name: 
Castle Pass and Andesite Ridge
Donner Summit Area
Date and time of observation: 
Fri, 01/26/2018 - 12:00
Location Map: 
United States
39° 21' 30.2436" N, 120° 21' 54.1656" W

Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain

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

Today's observations on Andesite Ridge focused on looking for buried surface hoar and examining wind slabs along the ridgetop.

A comparison snowpit was dug at the site of the Jan 22 avalanche class pits (noted lat/long) that reported surface hoar buried 5 to 7 cm below the snow surface. A wet snow and mist event on Jan 22 produced an easy to identify thin crust for which to look for the surface hoar less than 10 cm below it. Snowpit tests targeting the snowpack to 30 cm below the old snow/storm snow interface were unable to produce any type of failure plane in the area of the surface hoar. Two additional snowpits were dug approx 100 m to the S on the same slope. Identical results were seen in these pits. It is believed that the buried surface hoar that was reported in this area pre storm is no longer an issue.

Snowpit photo 1 - Storm snow amounts measuring 50 cm after many hours of settlement.

Snowpit photo 2 - The thin crust where the buried surface hoar was expected to exist 5 to 7 cm below.

Observations along the ridgetop targeting wind slabs revealed areas of recent wind loading and some minor wind slab formation. Skier triggered cracking was minimal. Intentional cornice drops and ski cuts produced no results.

Significant amounts of storm snow 30 cm (1 foot) or more deep existed along the ridgetop. This snow is available for wind transport and is expected to create new wind slabs as it is drifted by increasing SW winds tonight and tomorrow.

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Weather Observations
Blowing Snow: 
Cloud Cover: 
50% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Air temperature trend: