The Relationship between Extreme Hourly Precipitation and Surface Temperature in Different Hydroclimatic Regions of the United States

In a changing climate, there is an interest in predicting how extreme rainfall events may change. Using historical records, several recent papers have evaluated whether high-intensity precipitation scales with temperature in accordance with the Clausius-Clapeyron (C-C) relationship. For varying locations in Europe, these papers have identified both super C-C relationships as well as a breakdown of the C-C relationship under dry conditions. In this paper, a similar analysis is carried out for the United States using data from 14 weather stations clustered in four different hydroclimatic regions: the coastal northeast, interior New York, the central plains, and the western plains. In all regions except interior New York state, 99th percentile 1-h precipitation generally followed the C-C relation. In interior New York, there was evidence that intensity scaled with a super C-C relationship. For the 99.9th percentile precipitation, interior New York displayed some moderate evidence of a super C-C relationship, the western plains showed little relation between precipitation and temperature, and the remainder of sites generally scaled with the C-C relationship. Also, if only July, August, and September precipitation is considered, all stations except those in interior New York have little relation between temperature and precipitation, suggesting that precipitation intensity during summer months may not be well constrained by the C-C relationship. Overall, the C-C relationship (or a variation thereof) does not appear to constrain extreme precipitation in all regions and in all seasons, and its ability to aid in constraining future predictions of extreme precipitation may only be relevant to certain locales and time periods.