Available potential energy (APE), a measure of the energy available for conversion to kinetic energy, has been previously applied to examine changes in baroclinic instability and seasonal changes in the general circulation. Here, pathways in which the troposphere can build the reservoir of zonal available potential energy (A_Z) on synoptic (3–10 day) time scales are explored. A climatology of A_Z and its generation (G_Z) and conversion terms are calculated from the National Centers for Environmental Prediction–Department of Energy Reanalysis 2 dataset from 1979 to 2011 for 20°–85°N. Increases in G_Z and reductions in baroclinic conversion (C_A), source and sink terms for A_Z, are shown to equally contribute toward increasing A_Z in most seasons.  An examination of winter buildup periods in particular find that a diabatic enhancement of the meridional temperature gradient in the North Pacific jet exit region is a key factor toward increasing A_Z.  One such pathway toward achieving this enhancement is anticyclonic wave breaking. 

To explore this further, an examination of a climatology of anticyclonic and cyclonic wave breaking (AWB and CWB, respectively) is performed for A_Z buildups.  Widespread positive anomalies in AWB and negative anomalies in CWB are found for most A_Z buildup periods and are attributed to a poleward-deflected jet.  Less frequent west-east dipoles in wave breaking anomalies are attributed to elongated and contracted jet streams over the North Atlantic and North Pacific basins. Finally, a rigorous analysis of long-duration AWB events for winter A_Z buildup periods to an anomalously high A_Z state are examined using a quasi-Lagrangian grid shifting technique. These results suggest the critical role of North Pacific AWB events in diabatically enhancing the North Pacific jet exit region (and increasing Northern Hemisphere A_Z) through latent heating equatorward of the jet and radiative and evaporative cooling poleward of the jet.