As the warm air is forced upward, water vapor condenses into clouds and rain, which can sometimes be heavy along the front. A cold front, noted on weather maps by this symbol, is often characterized by quick changes and steady precipitation, followed by showery precipitation. A WARM FRONT has warm, moist air behind it that rises over the colder air it encounters. Rain may fall behind the front as the warm, rising air condenses. A warm front, noted on weather maps by this symbol, generally has a long frontal boundary -- the area where changes occur. STATIONARY FRONTS occur where warm and cold air meet but neither wins out. Unsettled weather can occur over a wide area near the frontal boundary.