 An occluded front is formed when a cold front overtakes a warm front. and usually form around mature low @-@ pressure areas . The cold and warm fronts curve naturally poleward into the point of occlusion , which is also known as the triple point . It lies within a sharp trough , but the air mass behind the boundary can be either warm or cold . In a cold occlusion , the air mass overtaking the warm front is cooler than the cool air ahead of the warm front and plows under both air masses . In a warm occlusion , the air mass overtaking the warm front is warmer than the cold air ahead of the warm front and rides over the colder air mass while lifting the warm air . 
