BUFFALO, N.Y. » After a three-day onslaught that dumped a historic 7 feet of snow on the Buffalo area and killed at least 12 people, the sun came out, but so did predictions of flooding caused by rain and temperatures of up to 60 degrees.

Weather Service meteorologist Jon Hitchcock said there might be trouble with drainage as snow and the uncollected autumn leaves underneath blocked catch basins.

"The biggest flood threat would be on Monday when temperatures are at their warmest," he said. "There could be general urban flooding."

"There’s roughly the equivalent of six inches of rain in the snowpack that will essentially be released over two days," Tobe said. "If it was released as rain it would be a monumental storm."

He said flooding would likely affect mostly basements and creeks.

The National Weather Service issued a flood watch for Sunday to Wednesday.

"We are preparing now for more flooding than we’ve seen in a long, long time," Gov. Andrew Cuomo said. Cuomo said the state was sending in pumps, boats, helicopters and high-axle vehicles that can operate in 4 to 5 feet of water.

"If we’re lucky we won’t need any of it," he said. "But prepare for the worst and hope for the best."

The snow remained a huge challenge. Officials were still urging people to put off nonessential travel so snow removal efforts could progress. Cuomo reopened a 132-mile stretch of the state Thruway that had been closed since Tuesday, but several exit ramps remained closed along the westernmost 75 miles.

"Assume if you get on headed west you can’t get off until Pennsylvania," the governor said. He said roads remain "very dangerous."

Local travel bans were beginning to be lifted Friday so delivery trucks can bring in food and other essentials to depleted supermarkets, the governor said.

Two more deaths were announced. A 50-year-old man was found Friday morning in his car, which was buried in snow in Cheektowaga, police said. The cause of death wasn’t immediately known.

One elderly resident of a nursing home, also in Cheektowaga, died after it was evacuated amid concerns of a roof collapse, a spokeswoman for the home said.

More than 30 major roof collapses, most involving farm and flat-roof buildings, were reported overnight, officials said Friday, and warm temperatures could make the snow even heavier.

Friday’s improved weather inspired some homeowners to climb onto roofs to shovel off the snow and reduce the danger of collapse.

"Five hours yesterday and that’s just the beginning," John Normile of Lake View said as he and his daughter and her boyfriend cleared up to 6 feet of snow from the roof of his ranch-style home.

"We’re getting really concerned about the weight of it," Normile said. "We’ve got to do it before the rain comes."

Associated Press Writers Chris Carola in Albany and Jim Fitzgerald in White Plains contributed to this report.