Most of the avalanches yesterday were failing on the uppermost layer of facets in the snowpack, and were 1 ½ to 2 feet deep, 100 to 1000’ wide, running all the way down to the flats. A few broke into the deeper weak layers, in shallow, rocky areas. There was significant activity at the upper elevations and the mid elevations below 9500’. Avalanches were triggered remotely from above, but can also be triggered from below and from the side.
It’s just plain dangerous out there - slopes that have not avalanched are hanging in balance, just waiting for a trigger. Many of yesterday’s avalanches broke well off ridgelines, meaning you can get out on to a slope, and have the slide break above you. Any slide you trigger on a steep slope today will be large enough to bury and kill you.
A note for the future: most of these avalanches are unfortunately leaving the deeper layers of large facets intact.
Park City Ski resort is planning on explosive work in the Murdoc/High Peak area with an avalauncher, as well as in the Daybreak area, including Main Mac, La Frontera, Nutty Putty, and Fin. Backcountry travel is not allowed in these areas.
Snowbird will be firing the Howitzer along the Gad Valley White Pine Ridge at 0530 on Thursday 1/11/18. A heads up for those traveling near the White Pine drainage.
The storm wrapped up quickly yesterday afternoon and temperatures finally cooled to more wintery norms, and are in the teens. This morning, light snow is falling in the mountains, and winds are brisk, from the northwest, in the 10 – 15 mph range, with gusts 25 to 35 mph. The highest peaks are averaging near 40 mph and gusting in the 50s. A look at the storm totals – both snow and water:Total Snow Total Water Upper Big Cottonwood 14 to 21" 2 - 2.5" Upper Little Cottonwood 8 to 14" 1.5 to 2" Mid Elevations, Cottonwoods 1 to 5" 1 - 1.25" Park City side 6 to 12" 1 to 1.35"
Lots of avalanches in the backcountry yesterday - a few naturals and many, many remotely triggered slides that averaged 1 1/2 to 2 feet deep and 100’ to 1000’ wide. Remotely triggered slides include 5 along the ridgeline from upper Days to the Silver Fork Headwall, in addition to No Name, West Monitor, Claytons, Twin Lakes Pass ridgeline, Radar Love and 10,420. The southeast face of Superior ran naturally to the willows. The resorts triggered large avalanche with explosives and ski cuts, with significant activity below 9,500’.
Photos: Silver Fork Headwall, Mark Staples
No Name, Mark White
A moist, northwest flow will keep skies mostly cloudy today, with light snow showers possible, especially this afternoon. An additional 1 to 3” of snow is possible. Temperatures will warm into the low 30s at 9,000’, and the northwesterly winds will increase this afternoon – averaging to 20 mph, with gusts to 35 at the mid elevations. High peaks will be gusting in the 50s. A few more inches of snow possible tonight into Friday.
Wind was a key player yesterday – many avalanches occurred where wind had drifted snow onto the slope, providing the extra weight needed to tip the balance.
This morning, the west to northwesterly wind is strong at the upper elevations, and forecast to increase at the mid elevations later this afternoon and overnight. Avoid all steep, wind drifted slopes and travel beneath them.
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This information does not apply to developed ski areas or highways where avalanche control is normally done. This advisory is from the U.S.D.A. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.