The series of storms that took hold of the Western U.S. and a large part of Colorado in the past month wreaked havoc for those in its path. Parts of California flooded, I-70 closed, and Lake Tahoe’s Crystal Bay, which received an estimated 24 feet of snowfall this January, had such high avalanche danger that residents were advised not to go outside until conditions stabilized. While the outdoor conditions were frightening, this storm brought much needed moisture from the Pacific to both the Rocky and Sierra Nevada mountain ranges. What was shaping up to be a below average snow year became one for the record books in a span of 20 or so days.
Hands became blistered from hours of shoveling the heavy powder and photos of buried chairlifts circulated the internet as skiers anxiously awaited the opportunity to fulfill their fat ski fantasies. The precarious snow conditions both in and out of bounds forced resorts in Lake Tahoe, Mammoth, and Arapahoe Basin to close temporarily.
Once slopes re-opened, they soon became sprinkled with an array of snow-covered faces, beaming from bottomless conditions. A video of post-storm opening day at Mammoth Ski Resort was even called “The Deepest Video of the Season” by Powder Magazine.
However, what the huge amount of snow means for backcountry skiing is a little more complex. The immediate effects include heightened avalanche danger, which, as seen with January’s storm, can be very severe. The extreme winds, reaching up to 100 mph gusts, caused wind loading and drastically increased avalanche danger on slopes that otherwise wouldn’t be very dangerous, making it increasingly more important to analyze conditions locally and choose aspects based on wind exposure. This being said, more consistent snowfall may have a longer-term stabilizing effect.
Warmer temperatures and deeper snow-packs slow the process of something called ‘depth hoar growth.’ These faceted, crystal-like layers, commonly found in the Colorado snowpack due to early season snow create a persistent weak layer, making Colorado backcountry terrain one of the more dangerous areas in the nation.
However, this season, thanks to a later snowfall and storms that are characterized by warmer temperatures, the depth hoar layer may not only be growing at a slower rate than usual, but could be prompted to start bonding and transforming earlier. Shorter breaks between storms have also decreased the formation of surface hoar crystals, which are a source of future weak layers. In the short term, storms definitely increase avalanche risk, but the long-term effects on snowpack are not as daunting as in other years.
Currently, Colorado’s avalanche danger is considerable given the recent storms and daily fluctuations, and the occurrence of an avalanche continues to be unpredictable. However, with such an impressive January storm cycle, and the storms predicted in the near future, a spring skiing season, full of stable corn snow and steep couloir exploration looks like it will be extending well into the summer.