As of about 4:45 p.m., a line of moderate-to-heavy rainfall was moving into the area and producing rainfall of an inch or more per hour, the National Weather Service reports.
The National Weather Service issued a flood advisory for this afternoon through 8:45 tonight for parts of Pennsylvania and New Jersey.
It is in effect for southeastern Lehigh County, southeastern Bucks County and all of Northampton County, in addition to all of Warren and Hunterdon counties.
As of about 4:45 p.m., a line of moderate-to-heavy rainfall was moving into the area and producing rainfall of an inch or more per hour, the weather service said.
"Excessive runoff from this activity will cause flooding of highways, streets and underpasses as well as other drainage areas and low-lying spots," the advisory reads.
The weather service warns against driving into areas where water covers the road, saying the water depth may be too great to allow vehicles to cross safely.