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
4/16/2013
Region
Salt Lake
Location Name or Route
Brighton to Catherine's Basi: Sunset, Rocky Points and out Dog Lake Chutes
Weather
Sky
Obscured
Precipitation
Moderate Snowfall
Wind Direction
Northwest
Wind Speed
Moderate
Weather Comments
Skies were obscurred most of the day with intermittent periods of overcast. During these overcast periods there were times when it was threatening to greenhouse as the sun was barely peering through the thinning cloud deck. At around noon the SE and low angle slopes began to become damp and go off. The NNW winds were gusting to the Moderate Category on the upper exposed ridges. Transport and or wind blown snow was loading in the Moderate Range. When the cloud deck was solid the temperatures felt more like December than April.
Snow Characteristics
New Snow Depth
2"
New Snow Density
Low
Snow Surface Conditions
Powder
Dense Loose
Wind Crust
Damp
Snow Characteristics Comments

As a result of the unseasonably cold temperatures, the upper one to two inches of the snow surface remained cold and dry above 9000 feet on all aspects and slope angles. Below this upper one to two inches, SE, S, SW and W aspects became damp as the day progressed; and as well all slopes with angles 30 degrees and less also became damp. With the extreme forecasted overnight lows, many of these slopes may dry out and actually not develop a significant crust for Wednesday. Spongy textures may be more of what you will find on Wednesday. Wind scouring on upper elevation northerly facing slopes near the tops of the ridges was observed. Incredible right side up winter powder was found on all other slopes throughout the day. Total snow for the latest storm is not in the 10 to 14 inch range. Overnight it appeared that another 2 to 4 inches came down. And, there were a number of squalls that came through during the day that appeared to add another 2 to 4 inches depending on aspect and elevation.

Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Red Flags Comments
The only natural activity that was observed were numerous Loose Snow Cold Dry Avalanches that appeared to run either Monday during the high PI periods and or overnight. These slides appeared to be runing about 6 inches deep in a density change in the new snow. No significant wet activity observed. When exiting it was easy to initiate Loose Snow Cold Dry Avalanches at and below 9600 feet on slopes with angles > 35 degrees. These were not entraining significant amounts of snow, and they were manageable. See photo. Of note: some riders appeared to initiate a small Wet Slab Avalanche in the steep cliff lines just down the ridge from Dog Lake Chute #2. See photo. This slide appeared to be 60 feet wide, six inches deep and ran approximately 150 feet. It appeared that it was intitiated by a rider descending and the person was able to escape off the slab to the rider's left. Wind loading on the Southerly slopes did not appear to be sensitive and or active in the upper elevations traveled. It appeared that the intensity of the sun (even though it did not come out fully) was helping settle out these new wind deposits/slabs as they were building. Small cornice drops were only initiating minimal activity in the upper couple of inches. Reports from the Wasatch County side of Sunset indicated similar activity.
Avalanche Problem #1
Problem
Wet Snow
Trend
Increasing Danger
Problem #1 Comments

Wet activity was not widespread in the upper elevation terrain traveled. In the mid/upper elevation it appeared that the S and SW was a bit more active. The fact remains that this latest new snow event has yet to have to deal with any direct/intense sunshine. So when this occurs there will be a widespread period of wet avalanche activity. With the slick crusts that were present on many of the slopes on the lower half of the compass, many of these slopes may have avalanches that may run farther than usual. This activity may not resume until Thursday when sunny skies are predicted. Yet, it only takes a good 15 to 30 minute period of direct sun to get things going.

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

The extreme cold overnight temperatures may help to further weaken the upper few inches of snow, and this may help surface sluffing become more active in the morning hours on Wednesday. These should not be a factor with good sluff management.

Sluffing in the NE and ENE Dog Lake Chutes.

Small rider triggered Wet Slab in the Lower Dog Lake Chute Area.