Spatio-Temporal Distribution of Deep Convection Observed along the Trans-Mexican Volcanic Belt

Abstract

Complex terrain features—in particular, environmental conditions, high population density and potential socio-economic damage—make the Trans-Mexican Volcanic Belt (TMVB) of particular interest regarding the study of deep convection and related severe weather. In this research, 10 years of Moderate-Resolution Imaging Spectroradiometer (MODIS) cloud observations are combined with Climate Hazards Group Infrared Precipitation with Station (CHIRPS) rainfall data to characterize the spatio-temporal distribution of deep convective clouds (DCCs) and their relationship to extreme precipitation. From monthly distributions, wet and dry phases are identified for cloud fraction, deep convective cloud frequency and convective precipitation. For both DCC and extreme precipitation events, the highest frequencies align just over the higher elevations of the TMVB. A clear relationship between DCCs and terrain features, indicating the important role of orography in the development of convective systems, is noticed. For three sub-regions, the observed distributions of deep convective cloud and extreme precipitation events are assessed in more detail. Each sub-region exhibits different local conditions, including terrain features, and are known to be influenced differently by emerging moisture fluxes from the Gulf of Mexico and the Pacific Ocean. The observed distinct spatio-temporal variabilities provide the first insights into the physical processes that control the convective development in the study area. A signal of the midsummer drought in Mexico (i.e., “canícula”) is recognized using MODIS monthly mean cloud observations.

Thunderstorm and hailstorm environments in Mexico

“…Similar seasonal patterns are observed in CH and FV subregions, with hailstorms concentrated in spring and summer. In these regions, the cold front activity, mainly the winter–spring transition (León‐Cruz et al, 2021; Pita‐Díaz & Ortega‐Gaucin, 2020), seems to provide favourable environmental conditions for decreasing the freezing level and increasing the probability of hail formation. The GM subregion shows mild hail activity in spring, summer, and autumn, while the YP subregion exhibits hail activity principally during winter, which can be explained by frontal systems passing over the region (Cahuich‐López et al, 2020), which tends to decrease the freezing level, favouring the hail formation.…”

“…Remarkably, a bimodal distribution is observed only in the NW subregion (active vs. inactive season), which has been related to the influence of the North American Monsoon (Boos & Pascale, 2021; Ramos‐Pérez et al, 2022). The highest thunderstorm activity in FV has been associated with the role of complex terrain features in generating deep convection (Brito‐Castillo et al, 2022; León‐Cruz et al, 2021). The GM and YP seasonal patterns are associated with the previously mentioned tropical activity (i.e., easterly waves and tropical cyclones) over the Caribbean Sea.…”

“…The approximate delimitation of each subregion was based on previous research about climatological characteristics. Six subregions were identified: the Trans‐Mexican Volcanic Belt (FV) with 14 observatories (León‐Cruz et al, 2021), the Yucatan Peninsula (YP) with 6 observatories (Valdés‐Manzanilla, 2022), the Northwest (NW) with 7 observatories (Valdés‐Manzanilla, 2015), the Gulf of Mexico (GM) with 8 observatories (Cavazos, 1999), the Central Highlands (CH) with 10 observatories (Peralta‐Hernández et al, 2008), and the Southwest (SW) with five observatories (Andrade‐Velázquez & Medrano Pérez, 2021). This previous analysis was necessary because no official Mexican database exists on severe weather.…”

“…For this portion of the country, intermediate-low shear and low-CAPE environments are typical for the formation of thunderstorms and hailstorms. Previous investigations have suggested the critical role of orography as a primordial mechanism for lifting and trigged convection (Brito-Castillo et al, 2022;Le on-Cruz et al, 2021). Further investigations are required to create a proper severe weather index for regions with such characteristics.…”

“…For example, mesoscale convective systems (MCS) over northwestern Mexico have been widely analysed during the North American monsoon (NAM) (Farf an et al, 2021;Ramos-Pérez et al, 2022;Valdés-Manzanilla, 2015). Likewise, the spatiotemporal distribution of precipitation and deep convective clouds over FV has been analysed, illustrating that both events are related to the orographic features (Brito-Castillo et al, 2022;Le on-Cruz et al, 2021). In addition, other research has examined the spatiotemporal distribution and characteristics of severe local storms, including hail, and some convective modes, as supercell storms (Concepci on et al, 2007;Edwards, 2006;Weiss & Zeitler, 2008).…”