Meteorological Causes of the Secular Variations in Observed Extreme Precipitation Events for the Conterminous United States

Abstract

Daily extreme precipitation events, exceeding a threshold for a 1-in-5-yr occurrence, were identified from a network of 935 Cooperative Observer stations for the period of 1908-2009. Each event was assigned a meteorological cause, categorized as extratropical cyclone near a front (FRT), extratropical cyclone near center of low (ETC), tropical cyclone (TC), mesoscale convective system (MCS), air mass (isolated) convection (AMC), North American monsoon (NAM), and upslope flow (USF). The percentage of events ascribed to each cause were 54% for FRT, 24% for ETC, 13% for TC, 5% for MCS, 3% for NAM, 1% for AMC, and 0.1% for USF. On a national scale, there are upward trends in events associated with fronts and tropical cyclones, but no trends for other meteorological causes. On a regional scale, statistically significant upward trends in the frontal category are found in five of the nine regions. For ETCs, there are statistically significant upward trends in the Northeast and east north central. For the NAM category, the trend in the West is upward. The central region has seen an upward trend in events caused by TCs.

Improvements in WRF simulation skills of southeastern United States summer rainfall: physical parameterization and horizontal resolution

“…The observed rainfall shows a sharp spatial gradient along the coastal regions (Fig. 6a), due mainly to land-sea heating contrasts during the summer (Wu et al 2009) and the contribution of tropical activities (Kunkel et al 2012). Such a rainfall pattern is generally captured by both schemes (Fig.…”

“…Furthermore, observed evidence shows that SE US summer rainfall, especially its spatial heterogeneity, is controlled largely by convective systems (Konrad 1997;Baigorria et al 2007;Kunkel et al 2012), indicating that realistically representing convective processes in cumulus parameterization schemes is important for an accurate simulation of SE US summer rainfall. Thus, an analysis of how cumulus schemes influence SE US summer rainfall simulation is imperative to improving rainfall simulation skills.…”

“…Over the coastal regions, summer rainfall is influenced by land-sea breezes and hurricane landfallings (Knight and Davis 2007), and the Appalachian Mountains often induce orographically uplifted rainfall. In addition, the passage of frontal systems also contributes to SE US summer rainfall (Kunkel et al 2012). Differences in the factors that control rainfall in different subregions of the SE US make the summer rainfall highly heterogeneous (e.g., Stooksbury and Michaels 1991;Baigorria et al 2007;Li et al 2013a).…”

Simulating North American mesoscale convective systems with a convection-permitting climate model

“…Deep convection is a common ingredient of many atmospheric extreme events and causes weather-related hazards globally (e.g., Doswell III et al 1996;Kunkel et al 2012). Deep convection causes major societal impacts due to flooding, wind gusts, hail, tornadoes, landslides, and debris flows.…”

Changes in weather and climate extremes: State of knowledge relevant to air and water quality in the United States

“…As noted by Kunkel et al (2012), there are various causes of extreme precipitation (and thus flooding) in the conterminous United States. Very generally, during the cold season widespread heavy precipitation is typically associated with extratropical cyclones, their concomitant warm and cold fronts, and the mesoscale convective complexes initiated along frontal boundaries.…”