  We extend the weak field approximation for the Glasma beyond the
boost-invariant approximation, which allows us to compute rapidity-dependent
observables in the early stages of heavy-ion collisions. We show that in the
limit of small fields, the weak field approximation agrees quantitatively with
non-perturbative lattice simulations. Furthermore, we demonstrate that the
rapidity profile of the transverse pressure is determined by longitudinal color
correlations within the colliding nuclei.
