BOISE — An unusual series of recent avalanches near the central Idaho resort area of Ketchum hit one home and closed a road for six days, and officials are warning skiers and snowmobilers about dicey conditions in the backcountry this weekend as another storm approaches.

A large wildfire that burned away much of the vegetation last fall is contributing to the severity of the avalanches, officials said, adding that could continue to be a problem in what appears to be an above-average snow year.

"What was unusual was the amount of snow and how many avalanches came at once," Blaine County Sheriff Walt Femling said. "We had 14 on Warm Springs Road alone. Talking to some of the residents who were trapped back there for six days, they said they hadn't seen this amount of snow and slides since '82."

Avalanches have killed at least 15 people across the West since Nov. 12, including nine in Washington alone. No one was injured in the Ketchum-area snowslides.

The National Weather Service on Thursday issued a hazardous weather outlook for the area around Ketchum, predicting another 10 inches of snow in the mountains.

Most of the recent avalanches occurred last weekend, and the county on Tuesday warned some residents in the Warm Springs area to not spend the night in their homes because of avalanche danger.

That warning was lifted Wednesday. Also on Wednesday, workers cleared the road to about dozen homes in the area, Femling said.

Those homes are some of the same ones ordered to evacuate ahead of the 78-square-mile Castle Rock Fire last summer.

Doug Abromeit, director of the U.S. Forest Service's National Avalanche Center, based in Ketchum, said the reason for the avalanches was not the fire, but a weak snow layer.

"You pick that sort of snow up and it just runs through your fingers," he said. "You can't make a snowball out of it."

About 19 inches of snow fell on that layer, creating the avalanche conditions that led to one hitting a house in Warm Springs on Saturday afternoon. The house had been built to withstand avalanches and no one was injured.

"Most of the houses built in the avalanche areas are not built to withstand avalanches," Femling said. "There are very few that are avalanche-engineered."

Abromeit said lack of vegetation in burned areas is likely a contributing factor on some of the avalanches.

"Especially in sage-covered slopes," he said.

Many of the hills and mountains that line the Wood River Valley, which contains the town of Ketchum, are favored by backcountry skiers and snowmobilers.

"In our big snow years, practically every slope that has snow on it that's steep enough to ski has tracks on it from Bellevue to Galena Pass," said Abromeit, noting the southern and northern ends of the valley.

But he said burned areas could be more prone to avalanches.

"Anytime something changes, that's a red flag," said Abromeit, a backcountry skier himself. "It's not going to be the same as it was a year ago."

That has Femling concerned, since he is responsible for backcountry rescues.

"We're getting a storm right now," the sheriff said Thursday afternoon. "I know it's going to be tempting this weekend. Fresh powder. I think we'll have quite a few people in the backcountry."