Synoptic magnetograms for three successive Carrington rotations (CRs 2152, 2153, and 2154) show some longitudinal patterns of evolving active regions; in each hemisphere the two circled active regions are evolving in such a way that the distance between them is increasing, as roughly depicted by the magenta and aquamarine lines connecting active region centroids in the left three panels (a). The northern hemisphere active region shows prograde propagation in longitude while the southern hemisphere one shows retrograde propagation. (b) The right panels (gray-scale magnetogram images) show images in a Carrington grid and the full disk. What causes such pattern changes and what are the implications for space weather?