As much as 10 inches of rain has fallen in the Ohio Valley since Friday, causing flooding, necessitating water rescues and creating a mudslide near Lexington, Kentucky.
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Parts of southern Indiana have seen 10 inches of rain, while up to half a foot fell in parts of Ohio. Other parts of Kentucky have reported 5 inches.
There were more than 100 reports of damaging storms on Monday that ranged from the Rockies to the East Coast, including five reported tornadoes. Parts of Texas saw tennis ball-sized hail.
More heavy rain and storms are expected on Tuesday for much of the nation.
Flood alerts have been issued from Illinois to New Jersey.
In the Plains, the combination of a new system from the West with an already-existing one means severe storms are forecast from Texas to Kansas, with the biggest threat damaging winds and large hail -- with an isolated tornado a possibility.
Some areas over the next few days could see additional heavy rain, locally more than 4 inches.