4B.5 Using velocity data from NWRT PAR and OU-PRIME to determine dynamics affecting rapid intensification of an EF4 tornado

Monday, 26 September 2011: 11:30 AM
Urban Room (William Penn Hotel)
Adam J. Smith, University of Oklahoma, Norman, OK; and D. Bodine, P. L. Heinselman, and P. B. Chilson
Manuscript (204.1 kB)

On 10 May 2010, the National Weather Radar Testbed Phased-Array Radar (NWRT PAR) sampled an EF4 tornado that caused one fatality in central Oklahoma. During this tornado, a series of volume scans were completed every 1 min, along with several interlaced scans that sampled the lowest four elevation scans in 8 s. From these data, we find a weak debris ball intensified in 1.5 min, with maximum reflectivity increasing from 50 to 67 dBZ within the signature. Outbound velocities also increased to as high as 65.5 m s-1 (146.5 mi h-1) to the southeast of the circulation center. These winds were observed in the same area where EF3 and EF4 damage occurred near Choctaw, Oklahoma.

In this study, we examine the evolution of NWRT PAR radial velocity to determine the effects of storm dynamics on the tornado's intensification. We also use scans from OU-PRIME and the Oklahoma City TDWR to verify velocity results using scans with greater azimuthal resolution than NWRT PAR, while WSR-88D data is used to examine tornado dissipation approximately 10 km from KTLX. With these data, we examine changes in the vertical vorticity as a function of height to determine if dynamically induced pressure perturbations impacted the tornado's intensity. We also determine how the rapid storm motion on this day may have affected locations where significant damage was observed. This analysis will allow for a better understanding of how rapid sampling and high spatial resolution may be used to detect regions of significant damage during fast-moving tornadoes.

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