Planned Website Outage: The UAC website will be down for maintenance on June 17 from 2:00 - 7:00 PM MT.
Ad
The National Forest Service Logo
icon-add Observation
Forecasts
Logan Ogden Salt Lake Provo Uintas Skyline Moab Abajos Weather Archives How to read the forecast
Observations & Avalanches
Submit Observation Observations Explorer All Observations Avalanches Fatalities Weather Place Names Map Archives
Education
Avalanche Class List UAC Class List Online Classes Resources and Tutorials Avalanche Awareness Develop Skills
Events
Store
About
Contact Who we are Core Values Staff Board of Directors Past Forecasters Sponsors Annual Reports Sign In
Blog
icon-add Observation
Donate / Join

Observation: Brighton Perimeter

Observation Date
1/6/2018
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon » Brighton Perimeter
Location Name or Route
Brighton Perimeter
Weather
Sky
Obscured
Precipitation
Light Snowfall
Wind Direction
West
Weather Comments
Dense fog and obscured skies prevented good visibility and the possibility of seeing any avalanche activity. Snowfall rate was sustained at S minus 1 thoughout the day with daytime totals at 9000 feet at 5 cm / 2 inches. Snowfall rates appeared higher at the upper elevations. The rain/snow line appeared to hover between 7500 and 8000 feet throughout the day. Winds were in the light range initially out of the SW and veering to the NW in the late afternoon hours, and no transport and or wind blown was observed. Yet, areas traveled were sheltered and protected.
Snow Characteristics
New Snow Depth
2"
New Snow Density
High
Snow Surface Conditions
Faceted Loose
Damp
Snow Characteristics Comments

Snowfall began at 0730 and prior to any new snow coming in the surface snow conditions were covered in a deep coating of NSF's. Early morning temperatures were barely below freezing, and as a result the new snow came in damp. Because of this, the new snow at these mid elevations appeared to bond well to the old snow surfaces. In steeper terrain, the depth of the prestorm NSF's allowed for loose snow avalanches initiating in the NSF's that were down 2 to 3 inches .

Red Flags
Red Flags
Recent Avalanches
Wind Loading
Poor Snowpack Structure
Red Flags Comments
Early reports of avalanches from the upper elevation zones of the Brighton perimeter appear to indicate the poor snowpack structure may have been receiving enough loading by late afternoon to tip the scales towards instability. Winds at the upper elevations appear to be contributing to this critical loading potential.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #1 Comments

At 1900 hours snow is still falling in the Cottonwoods, and it appears there is a tight band of Lake Effect that may be in play for at least another hour or two. Water content is now approaching 1/2 inch. With the moderate wind speeds in the highest elevations, and ample light speeds at the lower ridgelines, enough significant loading appears to be in place to initiate at least an isolated avalanche cycle overnight. Remote triggering appears to be possible on Sunday.. As cited above, the winds may also be contributing to this problem, and slab development may be enhanced because of this factor.

Avalanche Problem #2
Problem
Wet Snow
Trend
Increasing Danger
Problem #2 Comments

Both loose wet and shallow wet slabs may be a concern on Sunday with the forecast for clear skies and daytime highs at 9000 feet expected to be at and or near 40 degrees.

Any slides have the potential to dig down into the deeper faceted layers.

With the continued threat and the possibility of natural activity, either from overnight precip/loading, and or solar radiation during the day, a Considerable danger on Sunday appears likely on all the previously cited terrain aspects and elevations. Northeast and East aspects may be the worse.

Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Considerable