Radar Observations of the 3 May 1999 Oklahoma City Tornado

Abstract

The 3 May 1999 Oklahoma City storm is unique from a weather radar perspective because a long-track violent tornado passed within close range of several Doppler radars, because a detailed damage survey was conducted immediately after the event, and because high-quality visual observations of the tornado were available. The tornado passed relatively close (15?60 km) to two fixed-location Doppler radars: the National Weather Service Weather Surveillance Radar-1988 Doppler (WSR-88D) at Twin Lakes (KTLX) and the Radar Operations Center WSR-88D test radar at Norman (KCRI). Two mobile Doppler on Wheels (DOW) radars also observed the tornado at very close range (3?8 km). The data from DOW2 are nearly continuous for a substantial portion of the tornado's life and provide detailed information on the high-resolution velocity field in and around the tornado. These data permit good estimates of tornado rotational velocity and diameter. The data also allow comparison with tornado damage survey estimates of damage/intensity and with visual observations of tornado size. Further, one can compare the high-resolution DOW data to the lower-resolution WSR-88D observations to determine how much tornado information is lost because of the broader beamwidth (longer range) and longer gate length of the WSR-88Ds. Results of the study will be useful in determining how better to interpret future WSR-88D observations of near-range tornadoes, including any possible real-time estimation of tornado intensity and evolution.