  We consider the ferromagnetic q-state Potts model on a finite grid graph with
non-zero external field and periodic boundary conditions. The system evolves
according to Glauber-type dynamics described by the Metropolis algorithm, and
we focus on the low temperature asymptotic regime. We analyze the case of
positive external magnetic field. In this energy landscape there are $1$ stable
configuration and $q-1$ metastable states. We study the asymptotic behavior of
the first hitting time from any metastable state to the stable configuration as
$\beta\to\infty$ in probability, in expectation, and in distribution. We also
identify the exponent of the mixing time and find an upper and a lower bound
for the spectral gap. We also geometrically identify the union of all minimal
gates and the tube of typical trajectories for the transition from any
metastable state to the unique stable configuration.
