As a means to provide real-time access to ESS observations for other NWS offices, National Centers, and the research community, the NOAA Cooperative Institute for Regional Prediction (CIRP) has developed software to link together weather observations in the western United States from the roughly 350 stations in the National Weather Service (NWS) surface aviation network and an additional 2700 stations, including ESS stations. We refer to this collection of regional and local networks as MesoWest. Real-time and archival data and information regarding MesoWest can be obtained through the Internet at http://www.met.utah.edu/mesowest. MesoWest collects and processes meteorological data from over 60 participating organizations. ESS weather observations are currently available in the following states: Idaho, Montana, Nevada, Utah, Washington, and Wyoming. These observations are made available as a result of cooperative agreements between local NWS offices and the respective Department of Transportation agencies in each state. In addition to providing data at individual stations for operational use, CIRP creates objective analyses of meteorological data fields from the array of stations available in real-time. Surface analyses are generated by combining the MesoWest data streams with a background field provided by the National Centers for Environmental Prediction RUC2 analysis. These analyses rely upon the University of Oklahoma Advanced Regional Prediction System Data Analysis System (ADAS).