This message explains what an occluded front is, posted 2/28/2000 by weather
                 riders. Hope this helps! - C. Duvall, Rutgers Univ. Meteorologist 

                 A. Air and Fronts: 

                 Scroll down the message list to check out the message titled: 

                 " **Highs and Lows** " 

                 This message should help you to understand about how Highs and Lows work. 

                 Areas of warm air and cold air are separated on weather maps by fronts. A cold
                 front, usually blue with triangles along it, means that cold air is moving into an area
                 of warm air. The triangles point toward the direction the cold air is moving. When
                 cold air retreats backwards, warm air can take its place. A warm front is usually
                 red with half circles pointing in the direction the cold air is retreating. 

                 B. Occluded Front: 

                 Fronts revolve around Lows. Lows begin to weaken when the cold air traveling
                 along the surface around the Low- marked by the cold front- meets the cold air
                 retreating ahead of the warm front. When these two fronts meet, they form an
                 occlusion. This means that there is no longer any warm, moist, and therefore
                 unstable air "feeding" the Low at the surface. 

                 On the weather maps, an occluded front is usually purple with both triangles and
                 half circles alternating along the front. 

                 Hope this helps! 

                 - CD 3/1/2000