Observed summer weather regimes and associated extreme precipitation over Distrito Federal, west-central Brazil

The spatial and temporal variabilities of summer precipitation in west-central Brazil result in water supply variability and impact on water resources, agriculture and urban infrastructure. The diagnostic study of the variability of summer rainfall is accomplished through the relationship between the global atmospheric circulation and extreme precipitation over the Distrito Federal applying the technique of neural networks, the self-organizing (Kohonen) map and hierarchical ascendant classification. Nine weather regimes were identified (WRs), one group with four wet WRs with extreme precipitation, representing spatial variability of the active phase of South American Monsoon System (SAMS). One WR with the convergence zone in the central position of the country, two WRs positioned farther north suggesting be influenced by Madden–Julian Oscillation, and another WR further south may be influenced by Rossby waves. Five other dry WRs were associated with the break phases of the SAMS, or transitional regimes, without the formation of the convergence zone, but with an active low-level jet. In this group, less extreme precipitation events occurred in the central part of the country. The WRs relating large-scale atmospheric circulation and local precipitation enable better understanding of the intraseasonal variability in the regional scale.