UDOT PLANNED AVALANCHE CLOSURES!!

Forecast for the Salt Lake Area Mountains

Mark Staples
Issued by Mark Staples on
Monday morning, January 13, 2020
Today with increased winds and continued snowfall, the avalanche danger is HIGH on upper elevation slopes facing North, East, and South which should have fresh drifts from westerly winds.
Slopes at upper elevations not loaded by the winds have a CONSIDERABLE danger. Mid elevations are less likely to be loaded by winds and also have a CONSIDERABLE danger.
There is still a lot of snow at low elevations where the danger is MODERATE.
HEADS UP: There is simply A LOT of new snow. Riding conditions are fantastic, but the snowpack has gotten a lot of weight added to it which means a lot of stress. Be conservative today and give yourself a wide margin for error. More snow will fall today with more westerly winds that will load many slopes with additional weight.
Low
Moderate
Considerable
High
Extreme
Learn how to read the forecast here
Special Announcements
Get discount lift tickets HERE. Thanks for this generous support from Utah Ski Resorts and Ski Utah. All proceeds go directly to supporting the UAC.
Weather and Snow
Overnight a few more inches of snow fell in most places. Total snowfall since yesterday morning is 6-11 inches of very light snow which contains about 0.3-0.5 inches of water. Storm totals over the weekend are 20-35 inches of new snow.
Temperatures remain cold and are hovering in the low teens F this morning. Winds have increased since yesterday with gust about 10-15 mph higher. At ridgetops they are averaging 15 mph with gusts 20-30 mph from the WSW.
Today a cold front will descend over northern Utah and high temperatures will struggle to climb much above low 20s F. Wind speeds should continue at similar speeds. As the cold front passes, winds will briefly switch to the WNW before switching back to the WSW this afternoon. Snow will fall today with the heaviest snow this morning. By end of today about 6 inches should fall.
Riding and turning conditions are about as good as it gets.
Recent Avalanches
Yesterday along the Park City ridgeline a skier was carried in an avalanche on Squaretop that was about 40 ft wide and 15 inches deep. Ski areas reported many dry loose avalanches in the new snow with some soft slab avalanches in the new snow as well.
A notable avalanche occurred mid-morning in Little Cottonwood Canyon while the road was open. This slide occurred in the White Pine slide path and pushed a car off the road. Several things are notable about this slide. The path was shot with howitzer rounds before yet still produced an avalanche. UDOT shot the area with more howitzer rounds after the slide and didn't trigger any slides.
The take away is that even 105mm howitzer rounds are no guarantee, and there is always a certain amount of uncertainty when this much snow is falling. For us recreating the backcountry, we should give ourselves a wide margin of safety.
Photo of the White Pine avalanche (UDOT):
Also in the morning in Big Cottonwood Canyon, people spotted this natural avalanche coming off of Storm Mountain down the Powerhouse gully. (video from B. Torrey)
Ad
Avalanche Problem #1
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
The main things to watch for today are soft slabs of wind drifted snow. Yesterday Nikki and I were on Gobblers Knob where small terrain features with the slightest wind drifting had shallow slabs that would crack and slide downhill. With winds increasing since yesterday morning, I would expect plenty of wind drifting at the highest elevations and many of these slides should be occurring naturally. Look for signs of recent wind drifting from both WSW and WNW winds.
The good news is that many low and mid-elevation slopes exist that do not have any wind loading and just have amazing powder.
Below is a video showing winds transporting snow yesterday.
Avalanche Problem #2
New Snow
Type
Location
Likelihood
Size
Description
There is simply A LOT OF NEW SNOW. Mostly this new snow is producing loose snow avalanches or sluffs because it is such low density. These can easily bury a person if they run into terrain traps like creeks or gullies. Be cautious of what is above you and where you might go if carried in one of these slides. I don't expect many soft slab avalanches in the new snow on slopes not touched by the wind.
Avalanche Problem #3
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
Slopes that face southeast, south and southwest at the mid and upper elevations have a buried ice crust with a weak layer next to it that formed just before New Year's. This layer produced many human triggered avalanches after the New Year's storm. This layer should be gaining strength and may no pose a problem in the near future; HOWEVER, snowfall last week and this weekend has added a load of 20"-50" of snow containing 1.7"-2.65" inches of water weight. With this much weight and stress on this layer, I would not trust it for now. The best strategy is to avoid steep southerly facing slopes above 8000 feet. You can ride these slopes but simply choose ones less than 30 degrees in steepness
See additional information on a weak layer we have been finding on northerly aspects.
Below is a video from what Nikki and I found on south aspects on Gobblers Knob yesterday.
Additional Information
Northerly aspects: We continually have found a weak layer 2-3 feet deep on most other aspects besides south that is not associated with an ice crust. We've found it in Mineral Fork, Meadow Chutes. and Bountiful. Currently, it's producing spotty results (propagation) in our snowpit tests but we are yet to see any avalanche activity on this layer. We are mentioning this layer to keep you informed of what we are finding. It hasn't shown any other signs of instability, but with continued snowfall there's a chance this layer could come to life or it could simply get buried and go away. Stay tuned.
For now, after you have made all your assessments and determined it is a good idea to ride steep terrain on the north half of the compass, do a quick Extended Column Test as a last check. If it fractures across the entire column consider that a bad sign and choose a low angle slope.
General Announcements
This information does not apply to developed ski areas or highways where avalanche control is normally done. This forecast is from the U.S.D.A. Forest Service, which is solely responsible for its content. This forecast describes general avalanche conditions and local variations always occur.