Almost global existence for the Prandtl boundary layer equations

We consider the Prandtl boundary layer equations on the half plane, with initial datum that lies in a weighted $H^1$ space with respect to the normal variable, and is real-analytic with respect to the tangential variable. The boundary trace of the horizontal Euler flow is taken to be a constant. We prove that if the Prandtl datum lies within $\epsilon$ of a stable profile, then the unique solution of the Cauchy problem can be extended at least up to time $T_{\epsilon }\ge \exp ({\epsilon }^{-1}\mathrm{/}\log ({\epsilon }^{-1}))$.