Two people died, and hundreds of thousands of customers were without power in several states, as severe storms targeted the East Coast on Monday.
More than 630,000 customers were without power in 10 states as of 11:30 p.m. ET, according to poweroutage.us. North Carolina witnessed the largest number of outages, with power being cut off to at least 227,000 customers, followed by Pennsylvania, where about 149,000 customers in the state were without power.
In Florence, Alabama, police said a 28-year-old man was killed when he was struck by lightning in the parking lot of an industrial park.
The Anderson County Coroner's Office in South Carolina also confirmed the death of a 15-year-old who was struck and killed by a falling tree during a severe storm.
Thousands of flights were canceled or postponed. Cities seeing significant airport impacts include Atlanta, New York, Baltimore, Washington, D.C., and Boston. Thunderstorms are also expected to impact airports in Memphis, Dallas, Denver, Orlando, Tampa, Fort Lauderdale and Miami, the FAA said.
The FAA issued several ground stops Monday night for several airports on the East Coast, including JFK, Newark, Philadelphia, Atlanta and airports in the Washington, D.C., area.
In Washington, D.C., federal employees, including at the White House and the Pentagon, were instructed to leave work early Monday afternoon due to the weather.
The main threats Monday afternoon and evening are tornadoes and damaging winds.
Severe thunderstorm conditions are in effect for parts of Alabama, Georgia, South Carolina, North Carolina and Tennessee. The tornado watch extends across 11 states including Tennessee, West Virginia, Pennsylvania and New Jersey.
The severe weather is expected to disappear by Tuesday morning.
Over the weekend, stormy weather brought tornadoes, flash floods, power outages and uprooted trees across the United States.
There were more than 300 reports of devastating storms from Colorado to Virginia. 10 tornadoes were also reported — eight in Iowa, Illinois, Nebraska and Colorado on Saturday and two in Illinois on Sunday, according to the National Weather Service.
Storm damage was reported from Wichita, Kansas, through central Illinois and into Birmingham, Alabama.
Heavy rain led to dangerous flooding in parts of northeast Missouri on Friday evening, including the town of Kahoka, where more than 6 inches of rain fell in six hours. Water rescues were reported in the area.
Golf ball-sized hailstones were reported in Loveland, Colorado, and Elmena, Kansas, on Saturday.
More than 40,000 people were without power in Alabama on Sunday, as high winds of up to 61 mph caused trees to fall onto power lines.
ABC News' Clara McMichael and Teddy Grant contributed to this report.
