  Results are reported from an improved measurement of $\nu_\mu \rightarrow
\nu_e$ transitions by the NOvA experiment. Using an exposure equivalent to
$6.05\times10^{20}$ protons-on-target 33 $\nu_e$ candidates were observed with
a background of $8.2\pm0.8$ (syst.). Combined with the latest NOvA $\nu_\mu$
disappearance data and external constraints from reactor experiments on
$\sin^22\theta_{13}$, the hypothesis of inverted mass hierarchy with
$\theta_{23}$ in the lower octant is disfavored at greater than $93\%$ C.L. for
all values of $\delta_{CP}$.
