UDOT PLANNED AVALANCHE CLOSURES!!

Forecast for the Skyline Area Mountains

Brett Kobernik
Issued by Brett Kobernik for
Saturday, February 16, 2019
THE AVALANCHE DANGER IS HIGH ON UPPER ELEVATION NORTHWEST THROUGH EAST FACING STEEP SLOPES.
Human triggered avalanches are very likely. Natural avalanches may be occurring as I write this. It is not the time to get into big steep terrain.
Riding conditions will be excellent and we can still enjoy the snow snow this weekend. We just need to stick to lower angle terrain and make sure we are not underneath steep slopes that could come down on top of us.
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Avalanche Warning
WE HAVE ISSUED AN AVALANCHE WARNING THROUGH THE NATIONAL WEATHER SERVICE FOR THE NEXT 24 HOURS.
DAYS OF STRONG WINDS ALONG WITH RECENT DENSE, HEAVY SNOW HAVE CREATED DANGEROUS AVALANCHE CONDITIONS. STAY OFF OF AND OUT FROM UNDER STEEP WIND DRIFTED SLOPES. AVALANCHES CAN BE TRIGGERED FROM BELOW.
Weather and Snow
The Skyline picked up another 9 inches of snow along with fairly strong wind once again. The wind picked up from the south Friday evening with gusts to 55 mph. It then switched to the northwest with the frontal passage and there have been gusts to 50 this morning. It's much colder now than it has been the last couple of days with readings in the low teens in most mountain locations.
Recent Avalanches
I covered lots of ground yesterday from Huntington Canyon down through Spring City Canyon and found some very large avalanches. You can split them into two categories; new snow avalanches and avalanches that broke into old snow. Wind was a major factor in all of them.
First, I found a number of avalanches where only the new wind drifted snow avalanched. This type of avalanche is a fairly common occurrence. These new snow avalanches generally stabilize fairly rapidly.
Below: Wind drifted snow avalanches in upper Rolfson Canyon
Next, I started finding larger avalanches that broke deep into our buried "persistent weak layer" from mid December. These are a much more serious situation as these deeply buried weak layers of sugary snow are much harder to predict when they will avalanche and for how long will they continue to produce avalanches. The avalanches that I found were a result of a massive amount of snow loaded onto the slopes from strong southerly wind Thursday night into Friday morning.
Below: Numerous avalanches in Cow Fork of Cedar Creek. A couple of these cleaned out the entire winter's snowpack to the ground.
Below: Large avalanche in the South Fork of Spring City Canyon that broke into weak sugary snow from mid December.
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Avalanche Problem #1
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
WE HAVE JUST RAPIDLY LOADED THE SNOWPACK AGAIN WHICH IS STRESSING IT! Obviously from the avalanche activity, the deeply buried persist weak layers of snow have been pushed to the brink. The term "weak" in the phrase "persistent weak layer" is relative. It's not that the buried weak snow is all that weak right now, it's that we've rapidly added a a very large load on top of it. When we have super weak layers of snow that get buried, they can't hold very much snow before they avalanche. The current buried persistent weak layers are not all that weak, thus, they can hold a lot of snow before they fail. My thinking is that after some more time to settle, the snowpack will become fairly stable and we may stop seeing avalanches breaking into these deep weak layers. FOR NOW, ANTICIPATE DANGEROUS AVALANCHE CONDITIONS THIS WEEKEND.
Additional Information
This forecast is from the U.S. Forest Service, which is solely responsible for its content. This forecast describes general avalanche conditions and local variations always occur.