Previous work carried out by the authors suggests an anti-correlation between elevated dust concentrations and precipitation in Paso del Norte during the North American Monsoon. During monsoon season, both precipitation and dust storms appear to be associated with a moisture inflow approaching from Gulf of California (GOC) labeled as a “moisture surge.” A series of surface observations, soundings, and upper atmosphere circulation features are presented throughout the North American Monsoon over a period of eight years (1998 – 2006). The focus of this study is to recognize the onset, duration, and strength of GOC moisture surges and their link to dust storm activity and precipitation patterns in El Paso, Texas and surrounding areas.

Ground measurements of dew point temperature, wind speed, and wind direction were obtained from the Texas Commission on Environmental Quality (TCEQ). Surface aerosol mass densities were obtained from TCEQ and size resolved number concentrations were obtained utilizing the CLIMET CI-550 laser particle counter. Precipitation data and soundings were obtained from the National Weather Service and Comisión Nacional del Agua (México). In addition, NCEP-NCAR reanalysis data was used to identify upper atmosphere circulation features. These data sets were utilized (1) to recognize GOC moisture surges, (2) to investigate whether increased aerosol mass and number densities were responsible for decreased precipitation amounts, and (3) to evaluate atmospheric conditions during a moisture surge in the Paso del Norte region.