Greenhouse gases drove the increasing trends in spring precipitation across the central USA

The central USA experienced major flooding during spring 2019, with both the Missouri and Mississippi Rivers at major flood stage at several locations, causing levees to breach and widespread flooding. Here, we examine the total precipitation responsible for the spring 2019 flooding across the central USA from the perspective of weather types. We focus on the weather type (referred to as 'Midwest Water Hose' (MWH) (Zhang and Villarini. 2019 Climate Dynamics 53, 4217-4232. (doi:10.1007/s00382-019-04783-4))) that contributes the most to the total precipitation across the central USA. This weather type contributed to more than 70% of the total precipitation received across much of this region during January-May 2019, and it has been occurring increasingly frequently over the past 40 years. Furthermore, we found that climate model experiments with the historical change of greenhouse gas concentration can well reproduce the observed rising trend, while this is not the case for the natural forcing experiments. Therefore, the rising trend and the high frequency of the MWH can be mainly attributed to the rising greenhouse gases caused by human activities, rather than natural forcing. This article is part of a discussion meeting issue 'Intensification of short-duration rainfall extremes and implications for flash flood risks'.