Stellar Dendrite—The Double-edged Snowflake
The Alta snowflake logo, known worldwide in the ski community, did not come about by happenstance. The Alta Flake is based on the stellar dendrite, a snow crystal with hexagonal tree-like structure and branches. They are razor-thin, symmetrical in shape and create the fluffy snow that made Alta the birthplace of powder skiing.
The Alta Flake can also be a double-edged sword
Throughout Alta’s storied, snowy history, there has been a litany of snow-related events that remind us that the mountains are in charge. And while our ski patrol, mountain ops, and lift crews are the best in the business, sometimes Mother Nature gets the upper hand on all of us.
This past storm adds another chapter to Alta’s extensive history of weather and snowfall-related events.
Via Secrets of the Greatest Snow on Earth by Jim Steenburgh
The week got off to an unusual start. Just as Super Bowl Sunday came to a close, a cold winter storm made its way into Utah as a mass of cold air blanketed the state. Temperatures at Alta plummeted 47 degrees—from 43F to -4F in just 24 hours.
Snow started to fall in the Salt Lake Valley and surrounding mountain benches but did not impact the upper elevations of the Wasatch Mountains. By Tuesday morning, locations in the valley reported 18 inches of snow, while Alta recorded just 8.5 inches of 7% density stellar dendrites.
Subzero temperatures started to warm as a stream of tropical moisture and westerly winds took aim at Little Cottonwood. From Wednesday afternoon into Thursday morning, Alta received 9” of heavier, 10% density snow. This wet, wind-loaded layer overwhelmed the fragile dendrites from earlier in the week, triggering overnight natural avalanches in Little Cottonwood Canyon.
Thursday - February 6th, 2020
Interlodge went into effect at 5:30am on Thursday morning, requiring all residents, visitors, and employees to stay inside until avalanche control had been completed. Avalanche mitigation by the Alta Ski Patrol and the Utah Department of Transportation (UDOT) produced results as the snow and winds kept coming. While a handful of Alta Ski Patrollers, employees and skiers were able to make it up the canyon in the morning, the decision was made at noon to keep Alta Ski Area and Snowbird closed for the day. That evening, a one-hour window allowed hotel guests and employees to leave the canyon, everyone else was still under interlodge protocol.
Friday - February 7th, 2020
With the canyon on lockdown, the snow and wind kept coming. By Friday morning, an additional 19 inches of 19% density snow had fallen. Additional natural avalanches occurred overnight, burying miles of Highway 210.
The Town of Alta remained interlodged as further mitigation work from Alta Ski Patrol and UDOT produced extensive avalanche activity. Control work on Toledo Bowl created a slide that crossed the highway crashing into the Alta Peruvian Lodge parking lot, burying rows of empty cars. Another avalanche from the Hellgate area crossed Highway 210 and struck a cabin, shattering the windows and filling the residence with debris.
With Little Cottonwood Canyon looking more like a ski run than a highway, and more snow and wind on the way, the decision was made to keep the ski areas closed for a second day. Interlodge remained in place for the rest of the day and another night that saw 5 inches of 22% density snow and more wind.
Saturday - February 8th, 2020
As the sun rose on Saturday morning, the winds died down, the skies started to clear and Alta Ski Patrol and UDOT finished a third morning of control work. As UDOT went to work removing extensive debris from Highway 210, Alta employees started digging out the ski area. Cat crews, who had been working throughout the storm, finished their snow removal and grooming.
Around 9:30am on Saturday, the interlodge restriction was lifted, and hotel guests and Alta residents were allowed to step outside for the first time in 52 hours. many of them choosing to click into their skis and enjoy the 33” of new snow blanketing the slopes of Alta.
The now upside-down snowpack didn’t ski like a typical Alta powder day, but after two-plus days of confinement, it didn’t really matter.
Highway 210 finally reopened at noon on Saturday—walls of avalanche debris and uprooted trees lining the road.
Days after the storm, locals are still digging out and sharing their 52-hour Interlodge stories with friends and family around the globe. While these stories are shared for years to come, Alta and the ski community were reminded that the mountains are in charge—a not-so-subtle reminder of the power of Mother Nature and the frailty of the double-edged snowflake.
The 52-Hour Interlodge Storm by the numbers:
- All-time record consecutive interlodge: 52 hours
- Longest sustained 30+ mph westerly winds (since 1980) = 72 hours
- New Water: 5.52”
- New Snow: 33”
- Average Snow Density: 16.7%
- Typical February Snow Density: 7.55%
While 33" of snow is not an atypical storm for Little Cottonwood Canyon, the massive amount of water and sustained winds contributed to a unique avalanche problem. Thanks to all of the lodge guests and employees for patiently waiting out the storm. A huge shout out to all of the amazing Alta, Snowbird, and UDOT employees working around the clock to open the road and the mountains as soon as possible. And a final thank you to the 35-plus men and women of the Alta Ski Patrol that stand on the front lines and make the tough decisions.
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