Heat increases risk of deadly avalanches on Mount Hood

PORTLAND, Ore. (KOIN) — This week’s rapidly rising temperatures could create especially hazardous conditions on Mount Hood, the U.S. Forest Service Mt. Hood Climbing Rangers warn.

Six avalanches were reported on Mt. Hood in the past 12 days, according to Northwest Avalanche Center. An avalanche on Mt Hood’s West Crater Rim, which likely occurred within the last 24 hours, is said to have released at 10,000 feet of elevation and traveled 1,500 feet down the mountain, according to the rangers. These avalanche conditions caused some mountain climbing groups to turn back on Wednesday.

“The forecast for the coming days looks more like summer,” the Mt. Hood Climbing Rangers social media account states. “Climbers, including several guided groups, were turning around at the top of the Hogsback at 10,500 feet this morning due to wind slab avalanche potential. Warming the rest of the week should produce a new and different set of hazards: Icefall, possibly rockfall, wet avalanches, and weak snow bridges over glacial features. Rapid warming makes the mountain fall apart, increasing the likelihood of all these hazards, and could produce a very heads-up weekend on the upper mountain.”

USFS spokesperson Raven Reese told KOIN 6 News that the Mt. Hood Climbing Rangers are not official avalanche forecasters. However, the team does provide regular updates on mountain climbing conditions to provide safety information to anyone considering summiting the mountain.

The Mt. Hood Climbing Rangers are warning prospective climbers that the mountain could potentially see wet-slab avalanches this week as daytime temperatures rise as much as 20 degrees. Reese said that a wet-slab avalanche is an avalanche that falls as a slab when meltwater from rising temperatures weakens a layer in the snowpack. These wet-slab avalanches are considered as dangerous as traditional slab avalanches and often occur during periods of intense or prolonged rises in temperature. However, they are hard to predict.

“Most people that die in avalanches, die in slab avalanches,” the USFS avalanche safety webpage states. “Slab avalanches occur when a more cohesive or harder layer of snow sets on top of a less cohesive or softer and weaker layer of snow. Sometimes the weak layer can barely support the layers above it and when additional weight like a skier or boarder is added to the upper layers, the weak layer collapses and the snowpack fractures and a slab avalanche occurs.”

While slab avalanches can be triggered by skiers and snowboarders, Reese said that avalanche conditions in developed ski areas vary from conditions seen in backcountry areas.

“Everyone traveling on the upper elevations of Mt. Hood should assess mountain hazards, no matter the time of year,” Reese said. “If current weather forecasts hold, climbers, skiers, snowboarders and anyone traveling in the backcountry upper mountain should be concerned with warming-driven hazards like wet avalanches and icefall later this week. Within developed ski areas, avalanche conditions can be quite different than in the backcountry due to ski area avalanche mitigation.”

Despite the potentially hazardous conditions in the coming days, all mountain climbing trails remain open on Mt. Hood this week.

“Many dynamic mountain hazards can be present on the upper elevations of Mt. Hood and the Forest Service does not close public use on the mountain for these often rapidly changing hazards,” Reese said. “That’s why it’s so important for climbers to be prepared and experienced. Climbers and backcountry riders must make their own assessment of hazards and choose terrain accordingly.”

People interested in climbing Mt. Hood can check the latest reports from the Climbing Rangers and research Mt. Hood climbing recommendations through the USFS planning and safety climbing webpage.

“Generally speaking, the snowpack tends to adjust well to slow-warming events but does not adjust well to fast-warming events like the one that may occur later this week,” Reese said. “It’s very important that anyone considering summiting Mt. Hood plans well in advance and adjusts their climbing objectives based on conditions they find on the mountain.”