The National Weather Service has issued a flash flood warning for Bethlehem, Easton and the whole Lehigh Valley until 9:15 p.m.
A flash flood warning means that flooding is imminent or occurring.
A slow-moving line of thunderstorms and showers just south of Blue Mountain that extends from the western border of Berks County to the Delaware River was detected by Doppler radar at 5:09 p.m., according to the weather service.
More than two inches of rain has fallen along this line.
Wind gusts of 40 mph are expected to accompany this storm, which can be expected to cause water to pond on roads, to fill poor drainage areas and to cause rapid rises to small streams and creeks.
Most flood-related deaths occur in cars, according to the weather service, which warns motorists not to cross water-covered bridges, dips or low water crossings.