Land Surface Influence on Incidence of Mesoscale Convective Complexes in CONUS

About half the spring and summer precipitation in the central and southeastern United States is associated with organized, propagating mesoscale convective systems (MCS). Heavy rainfall found in particular types of MCS, e.g. mesoscale convective complexes (MCC), often leads to flooding and other hydrological extremes. The occurrence of MCCs in global hotspots of land-atmosphere coupling increases the importance of understanding the soil moisture -precipitation interactions in their initiation and lifetimes. A number of previous studies have found evidence of both dry-positive and wet-positive soil moisture feedbacks for triggering convection. Increased latent heating from an anomalous wet soil surface moistens a stable planetary boundary layer (PBL), priming environmental factors that govern convection (e.g. increased CAPE, decreased CIN, LFC, and surface temperatures). In contrast, anomalously dry soils can impact convective initiation more strongly than wet soils through increased sensible heat flux, a decrease in CIN, and an increase in PBL height. With the use of a tracking algorithm based upon brightness temperature and contiguous precipitation thresholds, a dataset of MCC events over CONUS is created using long-term satellite network data and atmospheric reanalyses. These events are then partitioned based on concurrent and antecedent soil moisture anomalies, both dry and wet. We examine the hypothesis that both concurrent and antecedent soil moisture can influence the formation and propagation of MCCs in spring and summer over CONUS.