(CNN) -- The Buffalo area waits for the floodwaters to rise.
They're coming, that's for certain.
But how high and how widespread, that's another matter.
Warming temperatures forecast for Sunday will start to melt 7 feet of snow that was dumped on the area in upstate New York last week. Rain will add to the menace.
State officials aren't taking any chances. They've beefed up stockpiles of emergency supplies including generators and pumps and prepared nearly 180,000 sandbags.
Swift-water rescue teams also are in place, along with helicopters, in case anyone gets caught in a deluge of runoff waters.
Sunday's high should reach the mid-50s. Showers are in the forecast through Monday night.
And then there's the threat of more structure collapses as all the rain saturates the snow on the tops of buildings, making the load even heavier.
Several dozen roofs have already collapsed from just the weight of the snow, according to Erie County officials.
"We don't have a crystal ball," New York Gov. Andrew Cuomo told reporters Saturday. "We can't say exactly whether or not there will be a flooding problem. We can't say what kind of structure collapses we may have. But we anticipate both to some extent."
The area is under a flood warning. The National Weather Service says flood-prone areas will be inundated but warns there will be more widespread flooding, too.
"(We) expect 5 to 6 feet of water in some areas in a short period of time," Erie County Executive Mark Poloncarz said. The risk of flooding extends into Tuesday.
Commissioner Daniel Neaverth Jr. of the county Civil Defense/Disaster Preparedness Division told affiliate WGRZ that officials are "hoping for best, but we're also preparing for the worst."
It's a notion the governor echoes.
"Hopefully, we need none of this, and hopefully this was just an elaborate exercise in logistics that we will have done and then we will deconstruct, and everything will go back and people will say, 'Boy, the governor really made us waste our time bringing everything out there just to bring it back,'" Cuomo said. "I hope that happens."
A year's worth of snow in a week
The 86 inches that fell in some areas in three days last week is a typical year's worth of snow for Buffalo, according to the National Weather Service.
The deadly storm claimed 13 lives -- many due to heart attacks while clearing snow.
The death toll also includes one senior citizen who died of natural causes after or while being evacuated Thursday from a nursing home in Cheektowaga, officials said.
The storm also forced the NFL to reschedule Sunday's football game between the Buffalo Bills and the New York Jets. Instead of being played in Buffalo, it's now scheduled for Monday in Detroit.
For the Bills, even getting out of the Buffalo area had its complications. Before meeting at the stadium Friday morning to get on a bus to the airport, some of the players had to be picked up by snowmobile because of driving bans in certain areas, team spokesman Scott Berchtold said.