Improving Tornado Warnings with the Federal Aviation Administration's Terminal Doppler Weather Radar

Abstract

The potential role of the Federal Aviation Administration's Terminal Doppler Weather Radar (TDWR) to supplement the Weather Surveillance Radar-1988 Doppler (WSR-88D) for tornado detection is discussed. Compared to the WSR-88D, the TDWR has a narrower beam, lower scan angles, and faster update rates. The 11 August 1999 Salt Lake City, Utah, tornado is used as an illustration of the utility of the TDWR. The Salt Lake City TDWR was much closer to the tornado than the WSR-88D and the WSR-88D was 750 m higher than the TDWR. Because the tornado developed rapidly upward from a surface convergence line, the TDWR detected the formation earlier than the WSR-88D. Also, the vortex signatures associated with the tornado were much better defined by the TDWR. The enhanced spatial and temporal coverage provided by the TDWR network is shown. A significant improvement in tornado detection, as well as other low-altitude phenomena, would be gained. However, ground clutter and signal attenuation can degrade coverage. Ongoing efforts by the National Weather Service to incorporate TDWR data into operations are described.