Observation: Upper Weber Canyon

Observation Date
01/28/2018
Observer Name
S. Zimmerman-Wall, T. Matthews, W. Deutschlander

Region:

Location Name or Route
Upper Weber Canyon
Weather
Sky
Broken
Wind Direction
Southwest
Wind Speed
Light
Weather Comments
Low ceiling, warm, and humid to start the morning. Temps increasing and skies trending towards partly cloudy by noon. Light winds, cool in the shade. Atypical Uinta weather.
Snow Characteristics
Snow Surface Conditions
Powder
Wind Crust
Rain-Rime Crust
Snow Characteristics Comments
Riming on most aspects near tree line. Variable surface conditions, but generally soft and mostly skiable. Snow profiles continue to reveal poor structure (mid pack facets) on NW-N-NE-E facing slopes NTL/ATL. Sudden results in snowpack tests. Audible collapses across North and East aspects. CTM SC failing on buried SH down 39 ECTPM SC x 2 failing on buried SH down 39
Red Flags
Red Flags
Recent Avalanches
Wind Loading
Collapsing
Poor Snowpack Structure
Red Flags Comments
Red flags are at half mast. The snowpack is talking to us, large natural avalanches have occurred in the last 24 to 48 hours, and digging down on shady aspects shows multiple structural weaknesses. Mid pack facets down >60cm, isolated buried SH down 39cm, and stiffening slabs in between and above. Respect these layers moving forward. They will be slow to heal and the slabs above are supportable enough to lure you out onto them and then shatter, dragging you down with them.
Avalanche Problem #1
Type
Persistent Slab
Trend
Same
Problem #1 Comments
With winds dying down in our location, this issue was of most concern. Naturally occurring avalanches in the Giant Steps area (ATL bowl NE through S facing) since Friday were driven by overloading by wind, but the size, connectivity, and debris point to persistent slab. Mid pack facets are 2mm in size and a buried SH layer on isolated northerly terrain features are possible weaknesses. Even a seemingly small slab could get out of hand quickly as it steps down into these weaknesses.
Avalanche Problem #2
Type
Loose Wet Snow
Trend
Increasing Danger
Problem #2 Comments
With warming today and into the week, expect this issue to rise on steep slopes that receive solar input (ESE through WSW).
Comments
1. Snow profile @9600 NE facing terrain. Notice thin grey stripe of buried Surface Hoar in upper pack; mid pack facets (Photo: Matthews) 2. Buried SH down 39cm. (Photo: Matthews) 3. Buried SH down 39cm. (Photo: Matthews) 4. Giant Steps avalanches x 3. Did not see looker's left slide in the photo on the bulletin morning of 1/28. Looks to have happened overnight and may have been attributed to cornice fall. (Photo:Zimmerman-Wall) 5. Giant Steps (Photo:Zimmerman-Wall)
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Moderate
Snow Profile Coordinates