bent-back occlusion

(Also called back-bent occlusion.) An occluded front that has reversed its direction of motion as a result of the development of a new cyclone (usually near the point of occlusion) or, less frequently, as the result of the displacement of the old cyclone along the front.
The resulting movement of the occluded front is westward and/or southward behind its associated cold front. It also may appear as the westward extension of the warm front in some cyclones. Its subsequent evolution following the development of a new cyclone can give the appearance of a cold front, with a sharp temperature drop and strong increase of winds.

(Commonly called occlusion;