Heavy rain events, which often lead to flooding, affect millions of people every year. The heavy rain-producing synoptic patterns that cause flooding share common configurations, or fingerprints. Obliquely rotated Empirical Orthogonal Functions Analysis reveals six different mid-latitude Northern Hemispheric synoptic patterns that cause heavy rain events. These Empirical Orthogonal Functions are based on the spatial correlations of the standardized anomalies of four atmospheric fields: 850 hPa zonal wind component, 700 hPa meridional wind component, precipitable water, and mean sea level pressure. Ultimately, identification of the primary synoptic patterns may lead to better flood forecasts and to reduction of life and property loss.
