At least two people are dead -- one in Oklahoma and one in Iowa -- after severe weather hit the Plains this week.
Sixty tornadoes were reported across Texas, Oklahoma, Kansas, Missouri, Iowa and Nebraska within two days.
Flood alerts remain in effect in the Plains Wednesday. Another four inches of rain is expected in some of the already-flooded areas in the next 48 hours.
The most at-risk area is northeast Oklahoma through central Missouri, including Tulsa and Joplin, where large hail, damaging winds and tornadoes are possible.
Joplin was the site of a catastrophic tornado on May 22, 2011.
On Thursday, part of the storm system moves into the Northeast and brings a chance for severe weather from West Virginia to New England.
The Northeast is most at-risk for wind gusts, heavy rain, scattered hail and tornadoes during Thursday afternoon and evening.
The Plains will remain at risk for large hail, damaging winds and tornadoes at that time, too.
ABC News' Reed Mcdonough contributed to this report.