  We consider a conventional $\alpha-\Omega$-dynamo model with meridional
circulation that exhibits typical features of the solar dynamo, including a
Hale cycle period of around 20 years and a reasonable shape of the butterfly
diagram. With regard to recent ideas of a tidal synchronization of the solar
cycle, we complement this model by an additional time-periodic $\alpha$-term
that is localized in the tachocline region. It is shown that amplitudes of some
dm/s are sufficient for this $\alpha$-term to become capable of entraining the
underlying dynamo. We argue that such amplitudes of $\alpha$ may indeed be
realistic, since velocities in the range of m/s are reachable, e.g., for
tidally excited magneto-Rossby waves.
