Flash floods are occurring across the U.S., from Texas to New Jersey. Here's what you should know as risks escalate.

The National Weather Service urged people to avoid travel if a flash flood warning was in place for their area.

The risk for flash flooding won't just be confined to today, as data shows the risk for flash flooding remaining in place Thursday, Friday, Saturday, and likely on Sunday too. There will be some big gaps in the rain, though, including most of Friday, looking dry and pleasant.

The Center Valley area in Upper Saucon Township, where flooding was reported along Route 309, had a recorded 6 inches of rainfall, making it the highest rainfall total in the Lehigh Valley, according to the National Weather Service in Mount Holly, New Jersey. Other areas had about 1 or 2 inches of rain.

Camp Mystic's executive director began evacuating campers approximately 45 minutes after the National Weather Service issued a "life-threatening flash flooding" alert.

A flood watch is in effect into July 15 for more than a dozen counties as saturated ground gets drenched again.

Heavy rains slammed the Northeast and caused flash floods in the New York City subway system. CBS News' Rob Marciano has the latest.

More than 50 million Americans throughout the Northeast are under flood watches on Monday, with a significant risk of flash flooding in some areas. Flash flood warnings have been issued for cities including New York City, Newark, New Jersey, and Arlington, Virginia -- including the Reagan National Airport -- through Monday evening.