LOS ANGELES - Emergency crews in California scrambled Wednesday to shuttle food and medicine to mountain communities stranded by back-to-back winter storms that have dumped so much snow some residents can barely see out their windows.

In San Bernardino County east of Los Angeles, round-the-clock plowing is underway but it could take more than a week to reach some areas, said Dawn Rowe, chair of the county’s board of supervisors. Residents are dealing with as much as 7 feet of snow, and sheriffs’ authorities have conducted 17 rescue operations to help off-roaders and skiers. Emergency crews are trying to reach residents who need assistance.

In Crestline, the entire roof of Goodwin and Sons Market collapsed Wednesday as safety inspectors were on-site checking up on reported damage. Officials raced to salvage food that residents sorely need from its shelves.

Rowe said no one was injured.

“We know that roofs are starting to collapse,” she said. “There are other businesses that will likely be affected by the weight of the snow.”

The county has set up a hotline for residents dealing with issues like frozen pipes, roof problems and food shortages. The San Bernardino Mountains are a major tourism and recreation destination but also home to a large year-round population in small cities and communities around lakes and scattered along winding roads. About 80,000 people live either part- or full-time in the communities affected, said David Wert, a county spokesman.

Reprieve was on the way as the mountain community continued to dig out, with much of California expecting drier weather on Thursday. A key mountain section of Interstate 5, a major north-south highway, reopened Wednesday afternoon following closures due to snowy conditions, while blizzard warnings expired in the Sierra Nevada further north.

Residents of these towns are grappling with so much snow they’re running out of space to put it; clearing one area adds heaps to another. Grocery shelves had run bare of some items, like bread, and were running low on eggs and milk Tuesday. Cars remained buried under snow and roads closed.

At David and Kelli Góra’s home in Big Bear Lake, the snow on the roof is now touching the snow on the ground. They shoveled a small area to let their dogs go outside, but are mostly hunkered down.

“We’ve been through some big storms ... but this is just unreal,” David Góra said. “I’ve never seen anything like it anywhere.”

While the West Coast grappled with wintry weather, forecasters warned a new, powerful weather system will affect most of the lower 48 states this week. Six to 12 inches of snow could eventually fall in upstate New York, Vermont and New Hampshire, meteorologist David Roth said.

At the opposite end of the spectrum, record high temperatures were expected Wednesday along the Gulf Coast and into the Ohio Valley while the southern Plains to the mid-South braced for possible tornadoes Thursday, according to the National Weather Service.