A man walks along a snow-covered street on Thursday, Nov. 20, 2014, in Buffalo, N.Y. A new blast of lake-effect snow pounded Buffalo for a third day piling more misery on a city already buried by an epic, deadly snowfall that could leave some areas with nearly 8 feet of snow on the ground when it's all done. AP Photo/Mike Groll A woman walks along a snow-covered street in the south Buffalo area on Thursday, Nov. 20, 2014, in Buffalo, N.Y. A new blast of lake-effect snow pounded Buffalo for a third day piling more misery on a city already buried by an epic, deadly snowfall that could leave some areas with nearly 8 feet of snow on the ground when it's all done. Ken Velie clears snow from his driveway on Wednesday, Nov. 19, 2014, in Lancaster, N.Y. Lake-effect snow pummeled areas around Buffalo for a second straight day, leaving residents stuck in their homes as officials tried to clear massive snow mounds with another storm looming. Sue Radka helps shovel out a friends driveway on Wednesday, Nov. 19, 2014, in Lancaster, N.Y. Lake-effect snow pummeled areas around Buffalo for a second straight day, leaving residents stuck in their homes as officials tried to clear massive snow mounds with another storm looming. Mark Settlemyer, left, gets help clearing snow from the roof of his mother's house from Ken Wesley on Wednesday, Nov. 19, 2014, in Lancaster, N.Y. Lake-effect snow pummeled areas around Buffalo for a second straight day, leaving residents stuck in their homes as officials tried to clear massive snow mounds with another storm looming. BUFFALO, N.Y. (AP) - Roofs began to creak and collapse under the weight as another storm brought the Buffalo area's three-day snowfall total Thursday to an epic 6 feet or more. Snow-weary residents of western New York were asked by Gov. Andrew Cuomo to "pretty, pretty please" stay off slippery, car-clogged roads for another day as crews rushed to dig out. Some areas received close to 2 feet of new snow by Thursday afternoon. The wild card was an expected weekend warmup with rain - raising the specter of flooding and yet more weight pressing down on roofs, where the snow could absorb the rain like the blanket. Roof collapses were reported around the region, including cave-ins that prompted the evacuation of 15 to 20 people Thursday from a suburban Buffalo mobile home park. Homeowners and store employees climbed onto roofs to shovel off the snow and reduce the danger. The immediate concern Thursday was recovering from the 5 feet or more of snow that fell earlier in the week. National Guardsmen drove nurses to work their hospital shifts. State troopers helped elderly residents trapped in their homes. State officials assembled 463 plows, 129 loaders, 40 dump trucks from across the state. Some Buffalo-area schools were closed for the third consecutive day, burning through snow days with winter still a month away. A stretch of the New York State Thruway through western New York remained closed with more than 300 truckers idled at truck stops and service areas, waiting for the highway to reopen. With deliveries interrupted, some stores reported running low on staples like bread and milk. Officials also cast doubt on whether the region would recover enough for the Buffalo Bills to host the New York Jets on Sunday. The seats and field of the Bills' home stadium south of Buffalo were buried in snow. Homes and businesses in the snowy Buffalo area are supposed to be able to handle about 50 pounds per square foot on their roofs, according to Mark Bajorek, a structural engineer. He said it's possible some buildings in hard-hit areas are close to that limit now, with more precipitation on the way. Associated Press writer Michael Hill and Mary Esch contributed from Albany.