Session 15.4 Comparison of in-situ pressure and DOW Doppler winds in a tornado and RHI vertical slices through 4 tornadoes during 1996-2004

Thursday, 7 October 2004: 5:15 PM
Joshua Wurman, Center for Severe Weather Research, Boulder, CO; and T. Samaras

Presentation PDF (1.7 MB)

A pressure measuring device was placed in the path of a tornado on 15 May 2003. As the tornado passed over the instrument a pressure drop over 100 s of approximately 30 mb was noted, with several short period (5 to 20 s pressure drops of up to 15 mb superimposed. Simultaneously, a Doppler On Wheels (DOW) mobile radar was collecting two-dimensional data over the probe in the tornado. The DOW data permitted the core flow diameter of the tornado, and the translational speed of the tornado to be characterized. Using these radar based constraints, and the pressure history at the probe, the cyclostrophic wind was calculated and compared to the radar-observed windfield. The comparison resulted in close agreement. with peak windspeeds near 50 m/s. There was video and radar evidence of multiple vortex structure in both the tornado and surrounding flow consistent with the 5-20 sec spikes observed in pressure.

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