We study the spreading of correlated fluctuations through networks with
asymmetric and weighted coupling. This can be found in many real systems such
as renewable power grids. These systems have so far only been studied
numerically. By formulating a network adapted linear response theory, we derive
an analytic bound for the response. For colored we find that vulnerability
patterns noise are linked to the left Laplacian eigenvectors of the overdamped
modes. We show for a broad class of tree-like flow networks, that fluctuations
are enhanced in the opposite direction of the flow. This novel mechanism
explains vulnerability patterns that were observed in realistic simulations of
renewable power grids