The storm in this radar image is moving northeast toward the photographer. The line of weak reflectivity (light blue) to the east of the storm represents outflow of rain-cooled air from the storm. This outflow is what led to the shelf cloud in the photograph. An additional outflow boundary can be seen oriented southwest-northeast across Adams county. This outflow boundary was leftover from a weakening thunderstorm seen over Highland County. As the Brown County storm crossed this outflow boundary, it moved into an area of rain-cooled air from the earlier storm and lost its source of warm buoyant inflow. Therefore the storm weakened by the time it reached the photographer.