Skip to main content
U.S. flag

An official website of the United States government

How Might the May 2015 Flood in the U.S. Southern Great Plains Induced by Sequential MCS Unfold in the Future with Warming?

Presentation Date
Thursday, December 15, 2022 at 5:00pm - Thursday, December 15, 2022 at 5:10pm
McCormick Place - E350



The record-breaking rainfall that caused severe flooding in Texas and Oklahoma during May 2015 was produced by a sequence of intense mesoscale convective systems (MCSs). The MCS rainfall over much of the U.S. Southern Great Plains (SGP) was 200%-300% above normal during that period. The large-scale environments in which MCSs develop over the U.S. Great Plains will likely change in a warmer climate, leading to changes in MCS lifecycle and characteristics. In this study, we examine how the May 2015 flood induced by a sequential MCS event might change in the future climate. The observed sequence of MCSs passing over the SGP in May 2015 are successfully simulated using WRF with 3 km grid spacing. A simulation of the sequential MCS event in a warmer future climate was performed using the pseudo global warming (PGW) approach. Results show a 43% increase in the number of MCSs triggered in the western SGP, supported by enhanced low-level moisture and convective instability during the afternoon. MCSs in the PGW simulation have wider, stronger, and more numerous convective updrafts, enhanced convective latent heating, resulting in 41% increase in convective rainfall volume. In contrast, MCS stratiform rainfall volume changes are small, possibly due to an offset by enhanced ice sublimation and evaporation associated with elevated freezing level and reduced tropospheric relative humidity. The more favorable large-scale environments over the central SGP under warming and the resulting enhanced MCS convective intensity and precipitation and associated circulation feedback may be responsible for a shift of the rainfall pattern with more heavy rainfall over the western SGP and reduced rainfall to the east (Figure 1). More detailed analysis of the mechanisms underlying the rainfall changes and implications on flooding potential in a warmer future climate will be discussed.
Image removed.

Funding Program Area(s)
Additional Resources: