A Severe Thunderstorm Watch is in effect for Shelton until 9 p.m. Tuesday night. The watch covers both Fairfield and New Haven counties. Heavy rains are expected to fall throughout the night, creating potentially hazardous conditions. Additionally a Flash Flood Warning is in effect until 5:30 p.m. as the storms are expected to roll into this area at about 4, with heavy rain that could reduce visibility to zero. According to the National Weather Service, there could be excessive runoff from heavy rainfall that could cause flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as in drainage areas and low-lying spots.