Planned Website Outage: The UAC website will be down for maintenance on June 17 from 2:00 - 7:00 PM MT.

Observation: Green Slope

Observation Date
1/10/2018
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon » Brighton Perimeter » Green Slope
Location Name or Route
Wasatch County: Green Slope
Weather
Sky
Obscured
Precipitation
Light Snowfall
Wind Direction
Northwest
Wind Speed
Strong
Weather Comments
S1 snowfall rates throughout the day with intermittent squalls. Winds were in the strong category, especially on the exposed ridges and ridge lines. Wind blown and or transport was intense. Temperatures dropped steadily after 1100 hours. Skies were mostly obscured with patches of overcast; and as a result visibility was very limited and poor.
Snow Characteristics
Snow Surface Conditions
Powder
Dense Loose
Wind Crust
Snow Characteristics Comments

In the sheltered areas out of the WNW winds the snow conditions were very good and coverage is getting more acceptable and safe. In the upper elevation terrain, there was signficant wind damage, sculpting and thickening of the new snow from cross loading as well as top loading. The winds were variable in locations traveled and the terrain was affected accordingly.

Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Cracking
Collapsing
Poor Snowpack Structure
Red Flags Comments
There were reports of widespread cracking and collapsing from the Willows, and this red flag was not evident in the Green Slope and adjacent areas. Minimal cracking in the newly formed wind slabs was mostly shallow and not propagating. Poor visibility limited the possibility of seeing any natural avalanche activity, and travel today was done on moderate to low angle terrain only. With reports from several observations indicating reactivity and remote triggering, this possibility was likely had we ventured on and or closer to any steep terrain.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Same
Problem #1 Comments

The poor snowpack structure we have been experiencing for at least a month now appears to be at a critical stress versus strength state. Thursday may not see the same type of hare trigger reactivity, but this problem is still the number one concern due to the multiple layers of buried facets within the entire snowpack on almost all aspects and at elevations above 8500 feet. Of note, even SE aspects have facets below thin m/f crusts at the upper elevations. Of concern is the way the current slab structure may allow persons to get further out onto slopes before collapse failure.

Avalanche Problem #2
Problem
Wind Drifted Snow
Trend
Decreasing Danger
Problem #2 Comments

Wind speeds still appear to be in the critical loading velocity ranges at 2100 hours, and they may also not be as reactive on Thursday, but the underlying snowpack structure may keep them sensitive to human triggers. And, Thursdays forecast for winds more out of the WSW could tend to overload different aspects like in NE upper elevation exposed terrain.

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