The document discusses decadal and multidecadal variability in precipitation patterns across North America. It finds that the strength of low-frequency behavior varies by season and region, and is not consistently related to major climate modes like ENSO or PDO. While some areas exhibit strong decadal precipitation oscillations, the underlying causes cannot be assumed to be externally forced, as precipitation spectra often resemble white noise. Spatial smoothing and long tree-ring records suggest very decadal-dominated patterns may be a recent twentieth century phenomenon.