This session seeks contributions that focus on characterizing precipitation in arid to semi-arid regions through observation and modeling studies. Precipitation is often difficult to observe and predict because of the scattered nature both temporally and spatially in these regions. However, the precipitation that does occur in arid to semi-arid regions is an important component of the available water resources. Therefore, understanding the formation mechanisms, characterizing the spatial and temporal variability, and improving the prediction of precipitation are critical. This session seeks contributions that focus on characterizing the environment at small scale (e.g. aerosol distributions) to large-scale (e.g., synoptic influences) that influence the formation of precipitation. Also, the conveners are interested in contributions that focus on the measurement of precipitation using in situ (e.g., rain gauges) or remote sensing (e.g., radar, satellite) observations. Mesoscale to large scale climate modeling studies are also particular interest in this session. Finally, the conveners are interested in contributions that focus on improving the monitoring or the validation/verification of precipitation observations/predictions in arid to semi-arid regions.