(CNN) -- So much for April showers.
A large and unexpected storm came barreling through the Northeast on Monday, threatening to drop more than a foot of snow in some places.
Winter storm warnings remained in effect Monday night for parts of Pennsylvania, New York and West Virginia, according to the National Weather Service.
Earlier in the day, Newfield, New York, was reporting 10 inches of snow, while Ridgebury, Pennsylvania, had 8 inches. More accumulation was expected, especially in higher elevations.
CNN iReporter Quinten Johnson sent in a photograph from Smethport, Pennsylvania, where a sign advertising a spring bazaar was covered in snow.
"We've already seen broken branches, and we are worried about the power lines," he said. "Everyone is shaking their heads and they are like -- that is life. Everyone put away their shovels and snow plows and got out their lawnmowers, and it is snowing."
The blustery blast follows a mild winter that saw little snow and the warmest March on record.
"The last time we had a big snowstorm across the East Coast was back in October," when fall foliage was still on the trees, said CNN Meteorologist Rob Marciano.
"This has been a crazy, crazy winter" in the region, he said.
Snowstorms of this magnitude are very rare for this late in April. Forecasters expect record snowfall for this time of year in some areas.
The highest recorded snowfall for Pittsburgh on this date was a half-inch in 1956. Up to 5 inches of snow were forecast for Monday, the weather service said.
Snowfall rates in central Pennsylvania were expected to reach 1 inch per hour at times on Monday afternoon, said CNN Meteorologist Sean Morris.
One "bull's-eye is Dubois, Pennsylvania," he said.
Another is Erie, Pennsylvania, where snowfalls totals along the southern side of Lake Erie could reach 16 inches, Morris said.
"The snow will be heavy and wet. The weight of the snow accumulating on trees combined with gusty winds could cause branches to come down on power lines, resulting in widespread power outages," he said.
Pete Petriani, who heads Erie's Bureau of Streets, told CNN affiliate CNN affiliate WICU that depending on how heavily it snows, crews "may have to do a little filling up of the back of trucks just for weight if we have to go out and plow. But if it comes, we'll be ready. It won't be a problem."
Snowfall amounts of 6 to 14 inches are forecast for the Allegheny Mountains of western Pennsylvania and near Lake Erie, the weather service said.
The snow won't last long, Morris said. Temperatures are expected to rise into the 40s and 50s this week, with overnight lows remaining above freezing.
Late Monday morning, one weather watcher reporting to CNN affiliate CNN affiliate WIVB had recorded 5 inches of snow near Boutwell Hill State Forest, southwest of Buffalo.
A public works dispatcher said 4 to 6 inches of snow had accumulated "on the hilltops, somewhat less in the valleys" of Chautauqua County in western New York state by early Monday afternoon.
"We have a few limbs that have fallen, nothing too big yet, nothing we can't handle," said dispatcher Rick Heath. "All of our (plow) trucks are out, and we're looking at more snow tonight."
The system rained out both the Mets and Yankees baseball games on Sunday.
A "pattern shift in the jet stream over the weekend" caused the weather change, with temperatures dropping in the country's eastern half and spiking in the west, CNN Meteorologist Sarah Dillingham said. "This trend will continue through Tuesday and Wednesday," though by Wednesday, temperatures will be working their way closer to normal, she said.
CNN's Josh Levs, Ed Payne, Leslie Tripp, Jacqui Jeras and Cameron Tankersley contributed to this report.