Session 15.2 The vertical structure of a tornado: High-resolution, W-band, Doppler-radar observations near Happy, Texas on 5 May 2002

Thursday, 7 October 2004: 4:45 PM
Howard B. Bluestein, University of Oklahoma, Norman, OK; and C. C. Weiss and A. Pazmany

Presentation PDF (2.6 MB)

A mobile, W-band, Doppler radar scanned, at close range, portions of a tornado near Happy, Texas, on 5 May 2002. Simultaneous boresighted video images were also recorded, which facilitated correlating the radar-observed features of the tornado with its visual features. Range-height indicators (RHIs) of radar reflectivity and Doppler velocity were collected that detail, with high spatial resolution, aspects of the vertical structure of the tornado near the ground. Most of the RHIs showed a column of a weak-echo hole from about 60 m above the ground up to the top of the domain at 800 – 1000 m above the ground; the hole was roughly 40 percent broader about 100 m above the ground as it was above, resulting in a characteristic pear-shaped vertical cross section of reflectivity. In this tornado, the condensation funnel was much narrower than the width of the weak-echo hole; the visible debris cloud near the ground was approximately just as wide as the hole above 150 m. The mean depth of the debris cloud was around 200 m. The vertical structure of the Doppler-velocity field exhibited a narrow band of high wind speeds about 200 – 400 m above the ground, consistent with airflow inward toward and cyclonically about the tornado. Possible reasons for the observed structure of the tornado are offered. On 12 May 2004, more RHI data were collected in tornadoes in south central Kansas. Preliminary analyses may be shown and compared with the Happy, TX analyses.
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