1994-13 For Release: May 6--June 15, 1994 Contact: Joan Vandiver Frisch, Manager NCAR Media Relations 303-497-8607; FAX 303-497-8610 Email: jfrisch@ncar.ucar.edu VORTEX Putting Mobile Instruments on the Paths of Tornadoes NORMAN, OklahomaÑThe largest field program for tornado research in over a decade is placing up to 15 instrument-laden vehicles within a few miles of developing tornadoes to observe their formative processes. New forecast techniques for tornadoes and severe thunderstorms are also part of VORTEX, the Verification of the Origins of Rotation in Tornadoes Experiment, being conducted from April 1 to June 15 in the southern Great Plains in the first of two consecutive spring field phases. Much knowledge has been gained to date on the general weather patterns that produce tornadic storms. However, the exact process by which a supercellÑa long-lived, highly organized severe thunderstormÑproduces tornadoes is not yet clear. VORTEX is designed to document this process through measurements taken by an array of instruments much denser than any previously operating in and near tornadic thunderstorms. The experiment is testing 17 specific hypotheses on the formation and evolution of tornadoes, each with criteria for confirmation or refutation. Based at NOAA's National Severe Storms Laboratory (NSSL) in Norman, VORTEX field operations will take place over Oklahoma, northern Texas, and southern Kansas. VORTEX is jointly sponsored by the National Oceanic and Atmospheric Administration (NOAA) and the National Science Foundation (NSF) and is a component of the United States Weather Research Program (USWRP). The USWRP is a U.S. Government Interagency Program with the objective of improving short term weather forecasts. Institutions participating in VORTEX include the University of Oklahoma (OU) and its Center for the Analysis and Prediction of Storms; the National Center for Atmospheric Research (NCAR); the University Corporation for Atmospheric Research (UCAR) Office of Field Project Support (OFPS); NSSL, the University of California, Los Angeles; the Universities of Illinois, Massachusetts and Mississippi; the New Mexico Institute of Mining and Technology; Texas A & M and Texas Tech universities; the National Oceanic and Atmospheric Administration/National Weather Service (NOAA/NWS); and Canada's Atmospheric Environment Service (AES). There are 18 principal scientists, including Morris Weisman (NCAR) and over 100 other participants, including Jim Moore, Jose Meitin, and Scot Loehrer (OFPS). All 15 of the vehicles in VORTEX are equipped with top-mounted weather stations that report wind speed and direction, humidity, temperature and air pressure every six seconds. The vehiclesÕ' locations are being determined by Global Positioning System satellites and reported to a mobile field coordination center that directs the vehiclesÕ movement. Reports of wind speed and direction are automatically corrected for the moving vehicles using the satellite data. A number of scenarios for placing and moving the vehicles are related to the stage of thunderstorm or tornado development as well as the type of storm present (for example, high vs low precipitation, or fast vs slow motion). All vehicles will be in and near the same storm at the same time. In addition to the surface instruments, an airborne Doppler radar aboard a NOAA P-3 aircraft will also gather weather data. One mobile weather-balloon unit and two fixed units from NCARÕs Atmospheric Technology Division will launch radiosondes and collect data using an atmospheric sounding system (CLASS). Four other mobile CLASS systems will be operated by NSSL. From 20 to 30 metallic, half-shell ÒturtlesÓ about one foot (30 centimeters) in diameter containing weather instruments and electric field mills will be placed near roadsides ahead of tornadoes to measure their minimum air pressure. Winds will be measured by two mobile Doppler radars operated by OU professor Howard Bluestein, who in 1991 detected winds close to 300 miles (480 kilometers) per hour in an Oklahoma tornado. Three photography teams will take high-quality 16-millimeter movie images of tornadoes for later analysis of the three-dimensional wind field using stereo photogrammetry. Other meteorological data will come from existing measurement systems, including the state-sponsored Oklahoma Mesonet, one of the world's densest surface networks, with over 100 weather stations reporting every 15 minutes. NWS observational data will be combined with the special VORTEX research data and catalogued by UCARÕs OFPS for on-line access by researchers. Forecasters on assignment to VORTEX from the National Severe Storms Forecast Center, other NOAA sites, and AES, will issue one- and two-day outlooks from an experimental forecast facility at NSSL and the Norman NWS forecast office. NCAR is managed by UCAR, a consortium of 61 member universities with graduate programs in the atmospheric or related sciences, under the sponsorship of NSF. Further information concerning the U. S. Weather Research Program can be obtained from William Hooke, head, USWRP Program Office, 301-713-0460. Writer: Bob Henson, UCAR NOTE: Media are invited to join the VORTEX field operations. One car of reporters will be allowed to accompany the field workers each day. Reporters interested in the field work, or who would like to visit the operations center at NSSL on days when the experiment is not operating because of calm weather, should contact Robert Davies- Jones at NSSL, 405-366-0419.