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: West Willow

Observation Date
12/31/2018
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon » Willows » West Willow
Location Name or Route
Willow Heights/West Willow/Mule Hollow
Weather
Sky
Overcast
Precipitation
Light Snowfall
Wind Direction
Northwest
Weather Comments
Early morning light snow showers (S-1) with overcast skies gave way to few by 1100. Winds were in the low end of the moderate range only on the highest most exposed ridgelines with light to moderate wind blown and or transport observed. Temperatures appeared to drop during the day with 8 degrees at 0900.
Snow Characteristics
New Snow Depth
7"
New Snow Density
Low
Snow Surface Conditions
Powder
Wind Crust
Snow Characteristics Comments
Excellent riding in sheltered areas with the latest pre-frontal winds appearing to have done a good job at erasing the old tracks. All aspect rode well and the southerlies did not get adversely effected by the solar due to the cold temps and low angle sun. Wind damage up high.
Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Poor Snowpack Structure
Red Flags Comments
Early report from Pioneer of a wind slab most likely wasn't the one of this kind today. Route traveled did not yield any observations of any other slides, yet the high PI from the event yesterday most like also created density changes in the new snow that may have been sensitive as well. Poor snowpack structure out of the upper Cottonwoods once again confirmed with snow pit yielding these results: 115 HS, NNE, 9550', 28 degrees, CT28 SC in the DH just above the October rain crust. Rain crust 10 cm with 20 cm of slightly rounding 2.5 mm facets above it, and this is where the failure occurred. See photo of facets.
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Decreasing Danger
Problem #1 Comments
Most like found at upper elevation on exposed terrain.
Avalanche Problem #2
Problem
Persistent Weak Layer
Trend
Same
Problem #2 Comments
Multiple reactive layers observed in tests, with a buried NSF layer at 45 cm down, and a much more sensitive/reactive layer of seemingly buried nsf's at 60 cm down. Basal facets the biggest concern, yet not enough load to be an issue at this point.
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Moderate