| Trigger | Natural | Remote Trigger | Unknown |
| Avalanche Type | Unknown | Aspect | Unknown |
| Elevation | unknown | Slope Angle | unknown |
| Crown Depth | unknown | Width | unknown |
| Vertical Run | unknown |
Avalanche: Summit
Location: Fresno
Fresno to 2300′
Avalanche Details
Two avalanches - one ~D2.5 on a NE aspect of Colorado and the other a D2 on a NW aspect gully on Butch - that likely occurred overnight. Each started close to wind scoured ridgelines and debris looked to be slightly covered by new snow. There may have been other slides in the region... light was fairly flat throughout the day, and even these two weren't obvious when clouds were overhead.
Obvious signs of instability
| Recent Avalanches? | No |
| Collapsing (Whumphing)? | No |
| Cracking (Shooting cracks)? | Yes |
Observer Comments
Short cracks - some 6" deep - on the ridgeline where winds loaded small terrain features overnight.
Weather
Overcast to broken skies, occasional light winds from the south
Temps in the 20s down low, teens up high
Very brief period of very light snow mid afternoon
Snow surface
6-8" of new snow fell overnight! This surface layer was barely cohesive enough to stick together in hasty hand pits, and would shear from the old snow layer with light force. Except for on the ridgeline where overnight winds made small slabs that cracked underfoot, the new snow layer lacked cohesion to crack in areas showing no sign of wind affect (nearly every slope we traveled today). Ski penetration of 6 - 12" along the route.
Snowpack
Dug a pit - 2150', E aspect, 25 degree slope - to look at the Thanksgiving Crust, just off the ridgeline at a location that was slightly wind scoured before the overnight storm (height of snow was 100cm). In each of three pits over the weekend in the area, the faceting in and around the Thanksgiving Crust was different, but CTs would only fail under hard force if at all, and ECTs wouldn't fail by 30 taps (ECTX). That said, today's pit also had a consistent, thin weak layer that was suitable to test with a Propagation Saw Test, and it failed with a result of 35/100 END. Yesterday a pit on Colorado had a similar result (30/100 END), and both are considered unstable test results. See pit profile below!
Natural avalanche likely from overnight just a scoured ridgeline, on a NE slope of Colorado.
The gully closest in this photo had fairly fresh debris in it, and this natural avalanche looks to have started from near a ridgeline as well, on a NNW aspect.
Small cracks on features that loaded last night/today.
8" of new snow overnight at the pit location, as shown here in a quick shovel tilt! At this location, only decomposing precipitation particles could be found on the snow surface (no surface hoar).
Snowpack structure and test results just off the Fresno ridgeline, in a slightly wind scoured (prior to the overnight storm) location.
Ski penetration of 6-12" along the entirety of the route, along with broken skies and some brief very light snow showers late this afternoon!