The fact that different fronts travel at different speeds over the ground can lead to one front overtaking another. When this happens, it is called an Occluded Front.
Occluded fronts bring all the cloud, weather and hazards of both the cold and warm fronts. This often results in low cloud and heavy, continuous rain for extended periods of time, particularly when the occlusion is slow moving. The interaction of multiple fronts means the wind direction can change significantly over a short distance.
Occluded fronts often have embedded CBs – cumulonimbus clouds that are hidden behind/inside other cloud layers. A CB can easily be hidden from your sight by a layer of low stratus!
Here’s a synoptic showing a cold front overtaking a warm front, creating an occluded front: