A “dangerously large” avalanche was trigger by a snowboarder in a closed area within the boundaries of Whitefish Mountain Resort on Thursday.

According to a report from the Flathead Avalanche Center, the snowboarder triggered the avalanche in the Haskill Slide area, which was closed due to heightened avalanche danger. The avalanche was large enough to easily bury and kill a person, the center stated. It was triggered at the top of the slope and ran though the trees to the bottom of the black-diamond rated terrain.

The incident was called in by the group of people who triggered and witnessed the event at about 2:30 p.m., resort spokesperson Riley Polumbus said. The group said no one was caught in the slide, however ski patrol responded and conducted a search using transceivers, spot probing and an avalanche rescue K-9 as a precaution. The search, combined with witness interviews, allowed patrol to call the area clear.

According to the avalanche center, large explosives had been used the previous day in the same area in an effort to mitigate the avalanche hazard. Polumbus noted that the Haskill Slide area was closed Wednesday afternoon. Signs were posted at the summit of Big Mountain and in the Haskill area noting the closure. It was also listed on the snow report as closed.

A number of areas at the resort were closed Friday due to the continued risk of avalanches, including Hellroaring Basin, all of East Rim, Evan’s Heaven, Moose, Haskill Slide, Movie Land, and Cal’s Country. Polumbus said ski patrol added more closed signs as well as some “redline” rope and a sign at the bottom of Chair 1 warning of the closures.

Polumbus said ski patrol continued to monitor the snowpack Friday, even in areas below slopes that could slide.

An avalanche warning was issued by the Flathead Avalanche Center through Friday evening for the Fathead Range, Whitefish Range, Swan Range and Glacier National Park. The avalanche danger was rated as considerable rising to high throughout the day as temperatures warmed. Backcountry travel on and below steep slopes was not recommended.

“The snowpack, especially at upper elevations, became weak and faceted during last month’s relentless cold,” the Flathead Avalanche Center warned. “That loose surface snow is primed for [sloughing] as it becomes saturated with melt water.”

Wet slab avalanche can fail in unpredictable ways and entrain surprisingly large amounts of debris, the center warned. South, west, and even north facing slopes have seen recent slide activity.

On Monday, the Flathead Avalanche Center issued its avalanche forecast warning saying that although wet slab activity has diminished since Friday, the snowpack is still not refreezing at night.

“The potential for human or natural triggered wet slabs lingers on the sunniest, hottest aspects, where water has been channeling through weak layers for several days,” the forecast says. “Wet slabs are difficult to assess and even more difficult to survive if you get caught in one. Choose routes that reduce your exposure on and below suspect aspects before the day gets too warm and the snowpack turns to mush. If you step off your skis or sled and sink to your waist, you have outstayed your welcome in steep terrain.”