Natural deep slab releases on Mt. Tallac

Location Name: 
Mt. Tallac
Region: 
Desolation Wilderness Area (including Emerald Bay)
Date and time of avalanche (best estimate if unknown): 
Sat, 03/17/2012 - 08:27
Location Map: 
United States
38° 54' 36.5868" N, 120° 5' 11.0796" W
See map: Google Maps
US


Red Flags: 
Recent loading by new snow, wind, or rain
Obvious avalanche path
Observation made by: Public
Avalanche Observations
Crown Height: 
5 ft
Aspect: 
Northeast
Avalanche Width: 
500ft.
Terrain: 
Near Treeline
Avalanche Length: 
200ft.
Number of similar avalanches: 
3
More detailed information about the avalanche: 

These avalanches were seen from Kiva beach yesterday, Wed. March 21st.  Easily visible from this distance, so must have been quite large, I'm assuming failure of the deeply buried facet layer, but cannot be sure.  Also appeared to be some new snow on top of the slides, making me think they happened before the weekend storm cycle ended.

 

Pic. 1 -  This slide was on E facing terrain below treeline.  This location is the ridge separating the lower Cross drainage from  lower Northbowl drainage,  approximately the same elevation as the top of "sweat hill"  I would assume between 7000-7500 feet.  Looks like a big one, very wide, hard to tell how far it ran.

 

Pic. 2 - Multiple slides on the lower portion of the Cross Drainage.  Approx same elevation as slide in Pic. 1.  Conves rollover, just above the bottom most steep section of the Cross bowl.  Again, it seemed there was some new snow on top of the slides so they must have occured mid-storm.

 

There were tracks visible from my location on "sweat hill" and some other parts of the mountain, but none in the vicinity of these slides, so I have to assume natural release.  Viewpoint I would guess at least a few miles away which gives an idea of the size of these crowns.  Also numerous wet slides noted as well.

Avalanche info given above, (width, length, crown height) are estimates.

Avalanche Photos: 
Weather Observations
Air temperature: 
Above Freezing
Wind Speed: 
Calm
Precipitation: 
Air temperature trend: 
Static
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 

Gorgeous day yesterday when these slides were viewes,  but I assume they occured during last weekends storm cycle.  lot of assumptions here.