FROM THE WEATHER CENTER
by John Simon
A warm front is a front located at the leading edge of a warm air mass. Clouds form ahead of the warm front and are mostly Stratus clouds, and rainfall increases as the front approaches.
Fog can also occur with a warm front, followed by clearing, and the air is warmer and more humid when the front is gone.
Thunderstorms may be embedded among the stratus clouds ahead of the front and after the front passes the storm may continue.
So, in summary, a warm front is when warmer air is replacing colder air. When colder air is replacing warmer air, that would be a cold front.
On a weather forecast map, the surface location of a warm front is marked with a red line of half circles pointing in the direction the front is moving. On weather maps drawn in color, warm fronts are sometimes marked with a solid red line.