The storms left at least 16 people dead and three people missing.
The National Weather Service warned Monday of an "enhanced risk" of severe storms in the mid-Atlantic as it registered "record flooding" in Arkansas, Missouri and Oklahoma.
As storm damage assessment continues, officials will determine which areas have the greatest needs. Near Clever in south-western Missouri, a man tried to save his 72-year-old wife from floodwaters that swept away their vehicle, but her body was found when the water receded. Also, a 65-year-old woman in DeWitt in the eastern part of the state was struck and killed in her home by a falling tree, officials said.
A second death was reported Sunday, but details were not available.
The storms were expected to move into Alabama and continue towards MI.
A deadly tornado tore through one woman's dream wedding in East Texas as violent storms lashed the South and Midwest over the weekend.
Heavy rain in the Midwest is expected to continue on Sunday, along with wind gusts of 60mph.
Two toddlers were in a vehicle swept off a bridge in Hindsville, Arkansas; rescuers have recovered the body of the 4-year-old boy but have not yet found his 18-month-old sister.
In the St Louis area, as warnings were broadcast for severe thunderstorms, some people were told to evacuate and 33 rescues were conducted, mostly in the state's central and south-western regions, Missouri Governor Eric Greitens said.More news: Houston's Nene suffers season-ending thigh injury
Over the weekend, tornadoes hit several small towns in East Texas, killing four people.
The death toll from the storms was raised to 15 Monday, although authorities in some areas have issued conflicting reports on the number.
In a Sunday morning news conference, Canton officials said roads have been blocked due to downed power lines and fallen trees.
A Smith County dispatcher said the county had sent volunteer firefighters to Van Zandt County to assist as needed. The National Weather Service confirms at least five tornadoes struck Eustace, Caney City and Canton in Northeast Texas. Forty-nine people had been treated for injuries, she said.
"Given the significant multi-peril footprint across more than one dozen states, it remains far too early to provide an exact economic or insured loss estimate at this time", says Aon. The tornadoes flattened homes, pulled trees out, and destroyed a auto dealership in Canton, about 60 miles east of Dallas.
Video from local television stations showed uprooted trees and overturned cars along rural, wet roadways, along with flattened homes.
Tornado 2, around 1 mile east of Canton, has been given a preliminary rating of EF-0.
At least 54 people went to hospitals and one person is in critical condition, ETMC Regional Healthcare Systems spokeswoman Rebecca Berkley told The Associated Press. In addition, more than 4 inches of snow has been reported in some areas of the Oklahoma Panhandle.