Doppler weather radars provide valuable measurements that aid forecasters in preparing more accurate and timely warnings and short-term forecasts and that help other users to better understand a variety of atmospheric processes. Though computer algorithms are available to objectively interpret Doppler velocity data, weather decision makers also subjectively interpret the patterns found in Doppler velocity displays. This Guide was prepared to help Doppler radar users in the Northern Hemisphere become proficient in pattern interpretation—through the use of simulated patterns representing flow fields within clear air and widespread precipitation as well as within tropical cyclones and convective storms. The first edition of the Guide, prepared by the authors in 1987 under an agreement with the NEXRAD Joint System Program Office (forerunner of the WSR–88D Radar Operations Center), was used as part of initial WSR-88D training for National Weather Service forecasters. This second edition is slightly revised and contains Doppler velocity displays that use color scales that are color blind friendly. Since this Guide was prepared by federal government employees, it is not copyrighted. It may be freely copied and distributed with appropriate acknowledgments. PDF and HTML versions of the Guide, as well as the ability to download individual figures, are available at http://publications.nssl.noaa.gov.