High-resolution, mobile, W-band Doppler radar observations of the vertical structure of a tornado near Attica, Kansas on 12 May 2004

The lowest 500 m of a mature tornado was scanned in the vertical plane at close range by a mobile (truck-mounted), W-band, Doppler radar, near Attica, Kansas on 12 May 2004. The radar, which was designed and built at the University of Massachusetts at Amherst, was operated by students from the University of Oklahoma. With a 0.18 deg half-power beamwidth, the azimuthal resolution of the radar at the range of the tornado (centered at ~ 2.5 km) was only ~ 5 – 10 m and the pulse resolution was 30 m. The detailed structure of the tornado is described with the aid of bore-sighted video frames that allowed us to correlate the visual features of the tornado with the radar data. There was a pear shaped weak-echo hole inside the tornado, but it was filled in within several tens of meters from the ground; additional “crimps” in the reflectivity field were evident along the edges of the hole at about 400 m AGL. The highest tornado wind speeds were within the lowest 200 m AGL. High-resolution vertical profiles of the horizontal component of the wind will be shown. The results from this study will be compared to those from the study of the Happy, Texas tornado on 5 May 2002, already published in the literature.