More frequent intense and long-lived storms dominate the springtime trend in central US rainfall

Abstract

The changes in extreme rainfall associated with a warming climate have drawn significant attention in recent years. Mounting evidence shows that sub-daily convective rainfall extremes are increasing faster than the rate of change in the atmospheric precipitable water capacity with a warming climate. However, the response of extreme precipitation depends on the type of storm supported by the meteorological environment. Here using long-term satellite, surface radar and rain-gauge network data and atmospheric reanalyses, we show that the observed increases in springtime total and extreme rainfall in the central United States are dominated by mesoscale convective systems (MCSs), the largest type of convective storm, with increased frequency and intensity of long-lasting MCSs. A strengthening of the southerly low-level jet and its associated moisture transport in the Central/Northern Great Plains, in the overall climatology and particularly on days with long-lasting MCSs, accounts for the changes in the precipitation produced by these storms.

Mesoscale Convective Systems in the Asian Monsoon Region From Advanced Himawari Imager: Algorithms and Preliminary Results

“…Under global warming, the long‐term trend of MCS and its associated precipitation have increasingly drawn attention in recent years (Kunz et al, ; Masson & Frei, ; Prein et al, ; Schmidli et al, ; Taylor et al, ). For example, the springtime rainfall in the central United States exhibits a steadily increasing trend in recent years with longer durations and heavier rain rates, which is primarily attributed to the MCSs (Z. Feng, Leung, et al, ). Furthermore, both the intensification of low‐level jet and the enhanced moisture convergence (Z. Feng, Leung, et al, ; Higgins et al, ) account for the changes in precipitation characteristic of MCSs.…”

Future changes in the climatology of the Great Plains low-level jet derived from fine resolution multi-model simulations

“…Roughly one-third of the moisture entering this region is transported from the Gulf of Mexico by the GPLLJ 1 , and convergence downstream of the jet promotes the formation of thunderstorms and convective precipitation 2 . GPLLJs also influence the intensity and longevity of mesoscale convective complexes 3 , and diurnal variations of the GPLLJ help explain the summertime nocturnal precipitation maximum of the central plains 4 . An anomalously strong GPLLJ contributed to the central U.S. floods of 1993 5 , 2008 6 , and 2015 7 , and increased (decreased) precipitation in the northern (southern) plains observed during 1979–2012 was attributed to a northward expansion of the GPLLJ 8 .…”

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

“…MCSs can be identified in multiple atmospheric fields such as mid-tropospheric vorticity (Wang et al 2011), cloud-related fields such as cloud top temperatures (Feng et al 2016), or precipitation (Clark et al 2014). Here we use hourly precipitation because of its high socioeconomic relevance and the availability of the stage-IV dataset that allows a sound model evaluation.…”