Wind slab and forming sun crust on Fireplug.

Location Name: 
Fireplug
Region: 
Mount Rose Area
Date and time of observation: 
Tue, 03/29/2016 - 11:30
Location Map: 
United States
39° 19' 33.9348" N, 119° 54' 38.934" W
US


Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain

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

Sunny skies while in the Tamarack Peak area from 9 am to 1:30 pm today, with gradual warming conditions. Minor amounts of free water were forming within the surface snow on solar aspects and will become a sun crust by later this afternoon or overnight. Solar IR felt strong, but air temperatures in the area stayed in the low to mid 20s during the morning and mid day hours. No signs of loose wet instability were observed while in the Tamarack Peak area or seen from the Hwy in lower elevation portions of the 3rd Creek drainage.

The surface snow on northerly aspects in the Tamarack Peak area remained cold and unaffected by melt. Compared to yesterday in this area, recent storm snow had undergone settlement and a significant increase in bonding to melt-freeze crust at the old/new snow interface was noted.

Along ridgetops, NW winds last night were noted to have scoured NW-N-NE aspects, but left snow in place on E aspects. Near treeline SE aspect test slope features along the ridgetop (noted lat/long) held new wind slab that cracked fairly easily under skier weight (photo). Wind slabs on the test slopes were up to 30 cm thick, 1F hardness slab over a new snow weak layer 4F to F+ hardness.

Significant amounts of graupel were present within the recent storm snow, but did not present as a problematic weak layer in informal tests. In isolated areas on N aspect terrain steeper that 37 to 40 degrees, poorly developed near crust facets were noted on the underside of the crust at the old/new snow interface. These facets did not appear to be a problematic weak layer or appear the be widespread at this time.

Snowpack photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Calm
Precipitation: 
None
Air temperature trend: 
Warming