1. INTRODUCTION Over the next several years, the U.S. network of WSR-88D weather radars is expected to undergo significant hardware and software upgrades to allow the acquisition of dual- polarimetric (“dual-pol”) data. These upgrades are expected to result in improvements to echo classification, precipitation rate estimation, and data quality. The Joint Polarization Experiment (JPOLE) (Ryzhkov et al. 2005) demonstrated the operational utility of dual-pol radar information in operational forecasting and decision-making (Scharfenberg et al. 2005). These findings were made with KOUN, the prototype dual-pol WSR- 88D located at the National Severe Storms Laboratory in Norman, Oklahoma. Unfortunately, there was little winter precipitation recorded at the surface in central Oklahoma during JPOLE, leaving many unanswered questions regarding operational uses of dual-pol WSR-88D during significant winter storms. One potential use of dual-pol radar information during high-impact winter precipitation is the improvement of operator situation awareness of rapid spatial and temporal changes in precipitation type at the surface. While this clearly requires the use of data from multiple sources, it is important to identify the potential advantages dual-pol WSR- 88D data may provide before the network upgrade begins. Elmore et al. (2007) describe a project involving the collection of public reports of surface precipitation type in winter storms in central Oklahoma during the winter of 2006-2007. Data were collected during three winter storms, and this paper offers some preliminary observations of the corresponding dual-pol WSR-88D products. * Corresponding author address: Kevin Scharfenberg, NSSL/WRDD, 120 David L. Boren Blvd., Norman, OK, 73072. 2. DATA AND METHODOLOGY Three significant winter storms struck central Oklahoma during winter 2006-2007. Public reports of surface precipitation type were collected during each event, totaling about 2149 good data points, most of which were within 150 km of the radar. An example of observations within a 30 minute period on 30 November 2006 is provided in Fig. 1. Fig. 1. Example of surface precipitation type reports from the public on 30 November 2006 between 0330 UTC and 0400 UTC. The data analyst can display reports from any 30-minute period in Google Earth GIS software, and can click on any icon to view the full report, as shown. KOUN dual-pol WSR-88D data were available throughout the three events. This analysis focuses on analysis of the horizontal reflectivity (ZB h B) product, differential reflectivity (ZB DR B), correlation coefficient (ρB hv B), and specific differential phase shift (KB DP B). Information about these KOUN products can be found in Scharfenberg et al. (2007). This preliminary qualitative analysis focuses on a few key observation times in each of the three events. A more thorough quantitative P10.10 ANALYSIS OF DUAL-POL WSR-88D BASE DATA COLLECTED DURING THREE . SIGNIFICANT WINTER STORMS Kevin Scharfenberg*P P, Kim Elmore, Carey Legett, and Terry Schuur Cooperative Institute for Mesoscale Meteorological Studies, The University of Oklahoma, and NOAA/OAR National Severe Storms Laboratory, Norman, OK