  We report the non-equilibrium behavior of disordered superconducting Al films
in high Zeeman fields. We have measured the tunneling density of states of the
films through the first-order Zeeman critical field transition. We find that
films with sheet resistances of a few hundred ohms exhibit large avalanche-like
collapses of the condensate on the superheating branch of the critical field
hysteresis loop. In contrast, the transition back into the superconducting
phase (i.e., along the supercooling branch) is always continuous. The fact that
the condensate follows an unstable trajectory to the normal state suggests that
the order parameter in the hysteretic regime is not homogeneous.
