A 6-year-old boy was killed in Oklahoma on Thursday when the car he was in slid off a highway in the heavy rain.
No serious injuries or deaths were reported in Texas, though at least 10 people were hospitalized and about 170 homes were damaged.
Southeastern Texas remained under flood watches and warnings early Friday, as did parts of Louisiana and Mississippi, and more rain was predicted.
On Thursday a twister struck Bryan, about 85 miles northwest of Houston.
Cathy Rios, 54, said all she could do is pray as her mobile home was tossed from side to side.
"I just kept screaming and screaming and screaming to God, `Help me,"' Rios said. "It was just awful. I don't know how I got out alive. I was just waiting for a tree to fall on me or the wind to blow me away."
In nearby Robertson County, residents were plucked from treetops, homes and cars in at least six swift-water rescues. A shelter in Hearne took in about 170 people, and some homes reported as much as 12 to 18 inches of water inside.
An earthen dam on a small lake gave way, sending water through a nearby neighborhood and swamping a road under 8 feet of water, said Jerry Henry, Robertson County emergency management coordinator.
Witnesses in Oswossa, Mich. told CBS News Radio about a tornado that touched down Thursday. They said the twister hurled a grain bin approximately 600 feet and caused minor damage to a farm.
Mike Unterbrink said his experience felt similar to what he has seen in movies. He described how the sky turned dark, and the wind began to blow with tremendous force.
"You could see the funnel cloud," Unterbrink said. "You could see the debris in the funnel cloud going right up into the sky.
"I walked out from around the barn and here's the grain bin up in the air, spinning around with a bunch of debris going up into the sky."
The rains delayed and canceled some flights at Houston airports.
In Sequoyah County, Okla., a car slid off Interstate 40 and ran into a tree, killing the 6-year-old from Maryland.
Winds of 60 mph ripped the roof off a barn near Bristow and overturned a travel trailer in nearby Tulsa County. The high winds also downed power lines, leaving 20,500 customers in the Tulsa area without power, officials said.
Parts of North Dakota, meanwhile, reported 8 inches of snow, giving some residents a chance to fire up their snowmobiles as workers repaired electrical lines.
"They were cruising up and down the ditches having a good old time," said Kerry Mikkelsen, line superintendent for the Cavalier Rural Electric Co-op in Langdon. "Just so they can say they were snowmobiling in May."
Langdon residents estimated they got about 7 inches of snow from the storm, which also brought strong winds and heavy ice to the region. Minot, Rolla and Crosby each reported around 8 inches of snow.
Bismarck tied a record low for the date on Thursday, at 27 degrees, the National Weather Service said, and Dickinson set a record low at 22 degrees.
The Milwaukee area's sewerage district dumped hundreds of thousands of gallons of combined rainwater and untreated sewage into the Milwaukee and Menomonee rivers Thursday after days of soaking rains.
"I can't stress how disappointed we are that this happened. Unfortunately, this was such an intense rain, there was no other option," spokesman Bill Graffin said.
In Minnesota, the Roseau River crested at 20.5 feet — 4.5 feet above flood level — but the town of Roseau stayed dry, thanks to sandbagging lessons learned in a flood two years earlier, when the river reached 23 feet and caused more than $120 million in damage.
"We're officially changing gears from a flood-fight mode to a monitoring mode," Mayor Jeff Pelowski said Friday.