A severe thunderstorm watch is in effect for the area until\u00a09 p.m. Tuesday\u00a0night. 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\u00a05:30 p.m.\u00a0as the storms are expected to roll in at about\u00a03:30\u00a0with 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. Drivers are warned to not drive their vehicles into areas where the water has covered the roadway. Because flood waters are usually deeper than they appear, this could cause lives to be at risk. The weather service warned that just one foot of flowin water can be powerful to sweep vehicles off the road.