The influence of inverted troughs on the formation of mesoscale convective systems during the North American Monsoon

The North American Monsoon (NAM) contributes the most significant amount of annual precipitation from July to September over northwestern Mexico. The increase in deep convection during the NAM is due to the emergence of extensive cumulonimbus cloud agglomerations, known as Mesoscale Convective Systems (MCSs). Previous studies suggest that upper tropospheric inverted troughs (IVs) (200 hPa), which occur over the NAM region, induce favorable environmental conditions for the development and intensification of MCSs. This talk shows the relationship of VIs with the organization of MCSs that occur over the NAM region. GOES-13 infrared satellite images (2010-2013) and the CLAUS database (1984-2008) are used to identify the trajectory of MCSs. ERA5 reanalysis data (1984–2008) characterize the atmospheric and thermodynamic conditions induced by VIs and upwellings. The results show that MCSs developed mainly in July and August, beginning to decline during September. A similar behavior is observed in the VIs, as most  of them originate from tropical upper tropospheric trough (TUTT) detachments. It is concluded that 22.8% of all MCSs formed during the study period interacted with VIs and produced more intense precipitation, unlike MCSs that did not interact. Although this percentage is small, MCSs that interacted with VIs induced more moisture to be transported to mid-atmospheric levels (500 hPa), compared to those that did not interact. Therefore, detecting these systems is essential to determine the existence of intense precipitation events over the NAM region.