  A remarkable feature of two-dimensional turbulence is the transfer of energy
from small to large scales. This process can result in the self-organization of
the flow into large, coherent structures due to energy condensation at the
largest scales. We investigate the formation of this condensate in a
quasi-geostropic flow in the limit of small Rossby deformation radius, namely
the large scale quasi-geostrophic model. In this model potential energy is
transferred up-scale while kinetic energy is transferred down-scale in a direct
cascade. We focus on a jet mean flow and carry out a thorough investigation of
the second order statistics for this flow, combining a quasi-linear analytical
approach with direct numerical simulations. We show that the quasi-linear
approach applies in regions where jets are strong and is able to capture all
second order correlators in that region, including those related to the kinetic
energy. This is a consequence of the blocking of the direct cascade by the mean
flow in jet regions, suppressing fluctuation-fluctuation interactions. The
suppression of the direct cascade is demonstrated using a local coarse-graining
approach allowing to measure space dependent inter-scale kinetic energy fluxes,
which we show are concentrated in between jets in our simulations. We comment
on the possibility of a similar direct cascade arrest in other two-dimensional
flows, arguing that it is a special feature of flows in which the fluid element
interactions are local in space
