(Reuters) - The phenomenon known as thundersnow announced the arrival of a storm expected to dump more than a half-foot of snow on the U.S. Midwest on Saturday, more than a month into spring.
Midwesterners retrieved their winter wear from storage to trudge through a possible 6 to 10 inches (15 to 25 cm) of snow predicted by evening in the Chicago area and more than a foot (30 cm) in some isolated areas of Minnesota, Iowa, southern portions of Wisconsin and northern Illinois, forecasters said.
“It will be heavy at times,” said Meteorologist Andrew Orrison of the National Weather Service’s Weather Prediction Center in College Park, Maryland.
“It is pretty impressive for the end of April across the Midwest to be getting these kind of totals,” he said, attributing the storm to a late-season surge of cold air from Canada.
More than 200 flights in and out of Chicago’s O’Hare International Airport were canceled or delayed by late morning as the wet weather began rolling across the nation’s midsection. The heaviest impact in Chicago was expected in the late afternoon into evening.
“It will start out as rain, then gradually mix with snow, and change over to a heavy wet snow in the late afternoon, especially this evening, across the Chicago metropolitan area,” Orrison said.
By late morning, thundersnow - a thunderstorm that delivers snow rather than rain - and accumulating snow were reported across southeastern South Dakota, southwest Minnesota and northwest Iowa, he said.
“Even some of the bigger cities – including Chicago – may actually see a fairly substantial amount of accumulating snow by the time it ends later tonight,” Orrison said.
Once the storm system dissipates, temperatures were expected to rebound, at least into the 50s Fahrenheit (10 to 16 C).
After the storm, Midwesterners can look forward to some good news - and some bad news.
“The snow that accumulates will melt fairly rapidly. By Monday we’ll be near 60 degrees,” Orrison said.
Melting snow in already-flooded parts of the Midwest, however, may not be welcomed by farmers who for months have been facing devastation from ruined crops and drowned livestock.
“That will tend to slow the retreat of floodwaters ongoing across the Midwest,” Orrison said.
Reporting by Barbara Goldberg in New York; Editing by Matthew Lewis