Summer convective precipitation during monsoon flow against Mexico's Sierra Madres: effects of hygroscopic seeding

The water supply in the reservoirs of north central Mexico near Torreon depends on convective precipitation produced from late June to early October as monsoon flow crosses rolling hills and reaches the steep slopes of the Sierra Madres. Due to steadiness in the monsoon moisture flow, regular diurnal cycle, and light upper air motions, convective clouds form predictably in certain locations, providing a dependable experimental framework for cloud microphysics and seeding investigations.

Recent field experiments have suggested that effective hygroscopic seeding at cloud base not only accelerates the growth of large hydrometeors at cloud base, but also may impact the dynamics of the treated clouds (and nearby clouds) by concentrating the coupling of updrafts and downdrafts, lengthening the cloud lifetimes and enhancing nearby convection through a stronger surface gust front. Here, we use observations collected during field experiments and high resolution numerical modeling studies using the nonhydrostatic, anelastic Clark Model to examine the dynamics, microphysical processes, as well as the timing, quantity, and and distribution of precipitation in both seeded and unseeded clouds.