MADISON, Wis. — A strong weather system is expected to bring prolonged heavy rain to south-central Wisconsin from Friday night into Saturday, raising the risk of flooding in low-lying, urban and poor-drainage areas. A flood watch is in effect from late Friday night through Saturday afternoon for Columbia, Dane, Green, Iowa, Lafayette, Rock and Sauk counties. The watch warns that excessive runoff could cause flooding in rivers, creeks, streams and other flood-prone locations. Most communities are expected to receive between 1 and 3 inches of rain. Areas that experience repeated thunderstorms could see 3 to 5 inches or more, increasing the potential for localized flooding. Friday will begin dry in the Madison area before showers and thunderstorms become more widespread. Temperatures are expected to reach the mid- to upper 60s Friday afternoon, then fall to around 60 degrees overnight. The heaviest rain is expected Friday night and Saturday morning, with additional showers and thunderstorms possible Saturday evening. Residents in flood-prone areas should monitor updated forecasts and be prepared to act if warnings are issued. Drivers should never attempt to cross a flooded roadway, where water depth and road conditions can be difficult to judge. The unsettled pattern could continue into early next week, with intermittent showers and isolated thunderstorms possible through Monday and potentially Tuesday. Forecasters also expect cooler conditions, including highs in the mid-60s Sunday and lower 60s Monday.