A tornado watch is in effect from Delaware to Philadelphia to New York City to upstate New York as severe thunderstorms and torrential downpours pound the Northeast on Tuesday afternoon and evening.
In New Jersey, multiple tornado warnings were issued on Tuesday afternoon. At least three tornadoes have been reported so far in Pennsylvania and New Jersey.
Besides tornadoes, the Northeast storms are forecast to bring damaging wind gusts up to 70 mph, large hail and rainfall rates above 1 inch per hour.
Flash flooding poses a major threat to a large swath of the Interstate 95 corridor, from Philadelphia to New York City to Connecticut. Flooded roadways have already been reported in the New York City suburbs of Bergen County, New Jersey, and Westchester County, New York.
Further west and south, severe thunderstorm watches are in effect from Missouri to Virginia, including the cities of Louisville, Kentucky, Charleston, West Virginia, Cincinnati, Ohio, and Pittsburgh, Pennsylvania. Flooding is also expected in Tennessee.
More than 2,000 flights have been canceled Tuesday, with airports in New York City, Philadelphia and Washington, D.C., seeing the biggest impacts. Ground stops were issued at airports in New York City, D.C., Boston, and Baltimore.
New York City Mayor Zohran Mamdani is urging New Yorkers to "exercise caution."
"Go inside if there's thunder, heavy rain, or strong winds," he said on social media. "If you live in a basement apartment, know your exits and be ready to move to a higher floor if heavy rain begins."
Tuesday's storms come just days after New York City was inundated with pounding rain that flooded streets on Saturday.
Iowa flooding
Meanwhile, severe weather also brought dangerous flooding to Des Moines, Iowa, on Monday night.
Nearly two dozen cars were stranded on roads and five people were rescued, according to the Des Moines Police Department.
"We simply ask everyone to slow down, pay attention to changing conditions and make safety the priority," said Des Moines Police Chief Michael McTaggart.
ABC News' Melissa Griffin contributed to this report.