A MODERATE danger exists for human triggered wind drifts primarily in the upper elevations and steep exposed terrain. A scary MODERATE danger exists for large destructive avalanches several feet deep. Thinner snowpack areas in the upper Cottonwoods and areas along the periphery of the Cottonwoods are most suspect. Collapsing and cracking are unlikely to be present.
With warming temps and clearing skies, wet avalanche activity will be on the rise over the weekend. Anytime the sun comes out for prolonged periods of time, the sun-kissed slopes will become wet and unstable.
Hot Tip! Wind and sun-sheltered low angle terrain is 4 stars. Low Risk High Reward.
Recent and overnight wind drifts will be found in the higher elevations today and in the open bowls and exposed terrain. Most of the lingering drifts noted in the mid-elevations should be well on their way toward stabilization, but pockets of rogue unstable wind drifts can't be ruled out in these elevations.
The past week's storms bringing 4 - 6” of snow-water-equivalent and wind has stressed many of the older heretofore dormant weak layers formed in October and November. Due to weather and poor visibility, we know of only a few of these large avalanches from Monday. In the recent days, however, avalanche control work has triggered some very large avalanches at or near the ground. These monsters have all been in upper elevation northerly terrain in the Cottonwoods. None of these have been skier or snowmobile triggered, however, but a person finding a thin spot or triggering a more superficial avalanche may be enough to trip the trigger. Trending toward low-probability and high-consequence. Certainly any entanglement with one of these deep slab avalanches would be fatal. Photos below. (Wilson, Snowbird, White)
The mid-Dec and early Jan weak layers are also stressed from the week's loading events and may be more reactive outside of the Cottonwoods (Snake Creek, upper American Fork, Grandview/Bountiful Sessions). These avalanches may be found as well on mid-elevation southeast facing slopes.
Our second 3 minute Blog-cast is The Metamorphism Parable, read by retired UAC forecaster Tom Kimbrough. He begins, "Brethren and sisteren, today I want to speak on morality and the snowpack...there are many paths you can choose."
Are you new to the backcountry or looking to refresh your skills? The UAC has released a free 5-part avalanche skills eLearning series.
No reports of activity from the backcountry. At the ski resorts, avalanche control teams found 5-10" wind drifts that ran easily with explosives. Most impressive, however, was an explosive released hard slab into November snow layering on a steep northeast facing slope in upper LCC at 10,900'. Dimensions unknown, but the photo speaks for itself, courtesy Snowbird resort.
In his travels into upper Cardiff Fork, Mark White found that a large section of Cardiac Bowl and Cardiac Ridge naturalled Monday, also stepping down deeply into early season faceted snow and to the dirt in some places. INFO
The latest Week in Review is hot off the presses - INFO. As you can imagine, it's been quite the week -
Skies are partly cloudy with many areas picking up a trace to 2" overnight. Temps are in the teens. West-northwest winds are 10-15mph with gusts to 20. At 11,000', it's a different story. They've been blowing 40-45mph with gusts 65-75 through the night.
Total snow depths are 90-100" in the Cottonwoods and 50-60" along the Park City ridgeline. Some southerly aspects will be crusted this morning, but the wind and sun sheltered slopes are divine.
A building ridge to the west will keep us under a cool northwest flow today with clearing skies over the weekend. A system moves through on Monday, although the models are not in much agreement over if or how much snow we might see. Otherwise, the weather looks uninspired until just after the turn of the month.
Still, the winter has been good to us so far. I cherry-picked the Brighton snotel site to provide reference. Most areas are 100-125% of normal for this time of year and certainly far and away better than last season.
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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.
