Observations from Tallac

Location Name: 
Tallac
Region: 
Desolation Wilderness Area (including Emerald Bay)
Date and time of observation: 
Mon, 04/02/2012 - 11:00
Location Map: 
United States
38° 54' 53.262" N, 120° 6' 4.4604" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Rapid warming
Obvious avalanche path
Terrain Trap
Observation made by: Professional Observer
Snowpit Observations
More detailed information about the snowpack: 

Evidence of widespread natural activity towards the end of recent storm.

pic 1: Skier's right of lower Corkscrew. Crown visible under cornice, extended well out of frame, >500ft wide, but didn't run very far down slope due to decrease in slope angle in main drainage.

pic 2: Small crown on convex roll in mid Corkscrew.

Pic 3: Flagging on trees whole width of N Bowl, no evidence of debris lower than midslope bench at 8000ft. No crown or flanks visible, so unknown if slab or loose avalanche.

Pic 4: Debris in N Bowl buried by additional storm snow. Debris remained soft and skiable.

None of this natural activity appeared to have stepped down to deeper weak layers.

Although all of upper N Bowl had slid, without obvious flanks or crown, it was easy based upon flagging on trees and depth of new snow to judge where storm snow remained undisturbed. In these areas, ski cuts, mitt pits and ECTs failed to show ongoing instability within the storm snow. 30-65cm of storm snow in undisturbed areas, 20cm of storm snow on top of bed surface (previous crust) and debris. HS below N Bowl ridgeline >400cm.

Roller balls and small point releases on solar aspects. N, NE aspects above 8000ft remained unconsolidated. Very light E wind was not observed to transport snow, even though surface snow all the way up to ridgetop on N Bowl remained light and available for transport.

Snowpack photos: 
Weather Observations
Blowing Snow: 
No
Air temperature: 
Above Freezing
Wind Speed: 
Light
Precipitation: 
None
Air temperature trend: 
Static
Wind Direction: 
East
Accumulation rate: 
None
More detailed information about the weather: 

High, very thin clouds. Temps already above freezing by 9am.