The 30 May 1998 Spencer, South Dakota, Storm. Part I: The Structural Evolution and Environment of the Tornadoes

Abstract On the evening of 30 May 1998 atmospheric conditions across southeastern South Dakota led to the development of organized moist convection including several supercells. One such supercell was tracked by both a Weather Surveillance Radar-1988 Doppler (WSR-88D) from Sioux Falls, South Dakota (KFSD), and by a Doppler On Wheels (DOW) mobile radar. This supercell remained isolated for an hour and a half before being overtaken by a developing squall line. During this time period the supercell produced at least one strong and one violent tornado, the latter of which passed through Spencer, South Dakota, despite the absence of strong low-level environmental wind shear. The two tornadoes were observed both visually and with the DOW radar at ranges between 1.7 and 12.9 km. The close proximity to the tornadoes permitted the DOW radar to observe tornado-scale structures on the order of 35 to 100 m, while the nearest WSR-88D only resolved the parent mesocyclone in the supercell. The DOW observations revealed ...

[1]  R. Rotunno.  An Investigation of a Three-Dimensional Asymmetric Vortex , 1984 .

[2]  Erik N. Rasmussen,et al.  Fine-Scale Doppler Radar Observations of Tornadoes , 1996, Science.

[3]  Joseph B. Klemp,et al.  The Dependence of Numerically Simulated Convective Storms on Vertical Wind Shear and Buoyancy , 1982 .

[4]  Frank P. Colby,et al.  Convective Inhibition as a Predictor of Convection during AVE-SESAME II , 1984 .

[5]  Erik N. Rasmussen,et al.  Design and Deployment of a Portable, Pencil-Beam, Pulsed, 3-cm Doppler Radar , 1997 .

[6]  Richard Rotunno,et al.  A Study in Tornado-Like Vortex Dynamics , 1979 .

[7]  Douglas A. Speheger,et al.  Doppler Radar Wind Spectra of Supercell Tornadoes , 1993 .

[8]  Neil B. Ward,et al.  The Exploration of Certain Features of Tornado Dynamics Using a Laboratory Model , 1972 .

[9]  Joshua Wurman,et al.  The Multiple-Vortex Structure of a Tornado , 2002 .

[10]  C. Doswell,et al.  Severe Thunderstorm Evolution and Mesocyclone Structure as Related to Tornadogenesis , 1979 .

[11]  Peter H. Hildebrand,et al.  ELDORA observations during VORTEX 95 , 1996 .

[12]  Swarndeep Gill,et al.  Finescale Radar Observations of the Dimmitt, Texas (2 June 1995), Tornado , 2000 .

[13]  J. Xia,et al.  The Influence of a Local Swirl Ratio on Tornado Intensification near the Surface , 2000 .

[14]  R. Wakimoto,et al.  Observations on the Origins of Rotation: The Newcastle Tornado during VORTEX 94 , 1996 .

[15]  Joshua Wurman,et al.  The DOW Mobile Multiple-Doppler Network , 2001 .

[16]  B. Fiedler.  Wind‐speed limits in numerically simulated tornadoes with suction vortices , 1998 .

[17]  W. Petersen,et al.  Evolution of Cloud-to-Ground Lightning and Storm Structure in the Spencer, South Dakota, Tornadic Supercell of 30 May 1998 , 2003 .

[18]  Curtis R. Alexander,et al.  Centrifuging of Hydrometeors and Debris in Tornadoes: Radar-Reflectivity Patterns and Wind-Measurement Errors , 2005 .

[19]  M. J. Carpenter,et al.  Doppler Radar Sampling Limitations in Convective Storms , 1985 .

[20]  E. Rasmussen,et al.  A Baseline Climatology of Sounding-Derived Supercell and Tornado Forecast Parameters , 1998 .

[21]  Richard Rotunno,et al.  Numerical Simulation of a Laboratory Vortex , 1977 .

[22]  Andrew L. Pazmany,et al.  Observations of Tornadoes and Other Convective Phenomena with a Mobile, 3-mm Wavelength, Doppler Radar: The Spring 1999 Field Experiment , 2000 .

[23]  M. Moncrieff,et al.  The dynamics and simulation of tropical cumulonimbus and squall lines , 1976 .

[24]  Effects of volume averaging on the line spectra of vertical velocity from multiple-Doppler radar observations , 1982 .

[25]  John T. Snow,et al.  Characteristics of Tornado-Like Vortices as a Function of Swirl Ratio: A Laboratory Investigation , 1979 .

[26]  Robert E. McIntosh,et al.  Studies of the Substructure of Severe Convective Storms Using a Mobile 3-mm-Wavelength Doppler Radar , 1995 .

[27]  Tetsuya Theodore. Fujita,et al.  "Proposed Characterization of Tornadoes and Hurricanes by Area and Intensity," by Fujita, T. Theodore; SMRP Research Paper Number 91; Illustrations, Prints, Negatives, and Drawings, 1970. , 1971 .

[28]  Richard Rotunno,et al.  A Theory for the Maximum Windspeeds in Tornado-like Vortices , 1986 .

[29]  Curtis R. Alexander,et al.  The 30 May 1998 Spencer, South Dakota, Storm. Part II: Comparison of Observed Damage and Radar-Derived Winds in the Tornadoes , 2005 .

[30]  W. S. Lewellen,et al.  Large-Eddy Simulation of a Tornado’s Interaction with the Surface , 1997 .