(CNN) - Minnesota is setting records -- cold, cold records.
Snowfall topped 30 inches Wednesday -- making this month not only the snowiest February in history, but one of the top 10 snowiest months ever for the North Star State, according to the National Weather Service.
It also marked the first time Minnesota has seen more than 30 inches of snow since December 2010, when the weight of the white stuff caused the roof of the Metrodome in Minneapolis to collapse, the weather service said.
About 100 million Americans are facing the threat of winter weather and flooding into Thursday morning.
The potent winter storm had prompted officials to close schools in Minnesota and the federal government to close all its offices in Washington, DC, with a handful of exceptions on Wednesday.
More than 2,200 flights were canceled Wednesday and nearly 40% of them were scheduled to land or take off from Washington or Baltimore airports, according to FlightAware. Chicago, New York, Philadelphia and Newark, New Jersey, airports were seeing flights called off.
A mixture of snow, sleet, freezing rain and some flooding will linger across much of the East until Thursday morning while residents in the Southeast will face several rounds of rain into the weekend.
From Louisiana to Alabama, and the Ohio Valley, too, face the threat of dangerous flooding, forecasters said.
Coast to coast
The nasty weather has been pounding the entire country, as two separate storms -- one on each coast -- are bringing winter weather watches, warnings and advisories to the northern United States.
Initially, a warm moist air streaming north from the Gulf of Mexico combined with a colder storm system exiting the Rockies created a wintry mix Tuesday night that carried into Wednesday.
As of Wednesday night, much of the Pacific Northwest is still under winter weather warnings or watches. Las Vegas can expect an inch or two of snow, and those living in the mountains of Southern California should brace for heavy snow. Phoenix is under a freeze warning.
East Coast takes the brunt
About 3 inches of snow have fallen in Washington and Baltimore and a wintry weather is expected to last into Thursday. As warmer air mixes in, it could leave a thin layer of ice -- around 1/10 of an inch -- on roads and other surfaces in the region.
The heaviest snow, 10 inches, was seen in Pennsylvania and Minnesota while parts of Maryland have seen nearly 7 inches of snow, the weather service in a preliminary report.
Snow or ice is expected from Philadelphia northward to Boston. A few inches of snow could fall in the region before switching over to rain.
Students in the School District of Philadelphia -- the nation's eighth largest by enrollment -- were told to stay home Wednesday, but building engineers and those in administrative roles were instructed to report for work.
In New York and Baltimore, city and transportation officials warned commuters that the snow, sleet and freezing rain could make travel difficult.
"Use mass transit where possible. Allow for extra time and exercise caution while traveling," Joe Esposito, commissioner of New York City Emergency Management, tweeted.
The snow and wintry mix will make their way northward throughout the night, reaching Maine and northern New England by Thursday morning and turning into rain in the southern areas of Virginia and Pennsylvania.
Waves of rain soaking the South, especially Tennessee
Rain continues falling from the Ohio Valley into the Southeast and threatens to bring severe flooding to some areas through the end of the week.
Flood or flash-flood watches extend from northern Alabama and Mississippi northward to Ohio. In Tennessee, floodwater has begun covering some roads and authorities in Lebanon evacuated a campground as a nearby creek began rising.
Forecasters say to expect 2 to 4 more inches of rain but have also predicted 5 to 7 inches in parts of Tennessee, including Memphis and Nashville, through the end of the week.
Birmingham, Alabama; Louisville, Kentucky; Lexington, Kentucky; and Charleston, West Virginia, also face the threat of significant flooding.
The threat for heavy rain in parts of northern Alabama and Tennessee will diminish Wednesday afternoon, the weather service said, but may continue into central and northeast Alabama overnight.
As the rain continues through the Southeast, forecasters said, another round of heavy rain taking shape will slowly move, drenching the region through Saturday.
"The hardest hit areas will be from northern Louisiana to Kentucky, where an additional 2-4 inches of rain is expected. This is on top of the 2-5 inches that has already fallen across the same area in the last few days," CNN meteorologist Taylor Ward said.
Multiple waves of rain will affect North Georgia this week. Atlanta is likely to receive 2 to 3 inches of rain, with higher amounts expected in the mountains to the north.
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